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  • 774 Chapter 24

    The Chemistry of Life

    CHAPTER 24

    What Youll LearnYou will learn the functionsof the four major classes ofbiological molecules: pro-teins, carbohydrates, lipids,and nucleic acids.

    You will identify the build-ing blocks that form themajor biological molecules.

    You will compare andcontrast the metabolicprocesses of cellular respira-tion, photosynthesis, andfermentation.

    Why Its ImportantThe large biological moleculesin your body are essential tothe organization and opera-tion of its millions of cells.The structure of these mole-cules is directly related totheir function, and how theyfunction affects your healthand survival.

    The silk that makes up thisspiders web is, gram for gram,stronger than steel, yet it islightweight and stretchable.Spider silk is made of protein,a biological molecule.

    Visit the Chemistry Web site atchemistrymc.com to find linksabout the chemistry of life.

    http://chemistrymc.com

  • 24.1 Proteins 775

    DISCOVERY LAB

    Materials

    400-mL beakerhot plate10-mL graduated cylinderboiling chip10% glucose solutiontest tubetongsBenedicts solutionstirring rodother food solutions such as10% starch or honey

    Testing for Simple Sugars

    Your body constantly uses energy. Many different food sources cansupply that energy, which is stored in the bonds of moleculescalled simple sugars. What foods contain simple sugars?

    Safety Precautions

    Procedure

    1. Fill a 400-mL beaker one-third full of water. Place this water bathon a hot plate and begin to heat it to boiling.

    2. Place 5.0 mL 10% glucose solution in a test tube.

    3. Add 3.0 mL Benedicts solution to the test tube. Mix the two solu-tions using a stirring rod. Add a boiling chip to the test tube.

    4. Using tongs, place the test tube in the boiling water bath and heatfor five minutes.

    5. Record a color change from blue to yellow or orange as a positivetest for a simple sugar.

    6. Repeat the procedure using food samples such as a 10% starchsolution, a 10% gelatin (protein) suspension, or a few drops ofhoney suspended in water.

    Analysis

    Was a color change observed? Which foods tested positive for thepresence of a simple sugar?

    Objectives Describe the structures of

    amino acids and proteins.

    Explain the roles of proteinsin cells.

    Vocabularyproteinamino acidpeptide bondpeptidedenaturationenzymesubstrateactive site

    Section 24.1 Proteins

    An amazing variety of chemical reactions take place in living organisms. Atthe forefront of coordinating the numerous and intricate reactions of life arethe large molecules called proteins, whose name comes from the Greek rootword protos, meaning first.

    Protein StructureYou have learned that polymers are large molecules made of many repeatingbuilding blocks called monomers. Proteins are organic polymers made ofamino acids linked together in a specific way. But proteins are not just large,randomly arranged chains of amino acids. To function properly, each proteinmust be folded into a specific three-dimensional structure. The spider silkshown on the opposite page would not be the incredibly strong yet light-weight protein that it is if it were not constructed in its specific way. You willlearn in this section how proteins are made from their amino-acid buildingblocks and how different types of proteins function.

  • Amino acids As you saw in Chapter 23, many different functional groups arefound in organic compounds. Amino acids, as their name implies, are organicmolecules that have both an amino group and an acidic carboxyl group. Thegeneral structure of an amino acid is shown below.

    Each amino acid has a central carbon atom around which are arranged fourgroups: an amino group ( NH2), a carboxyl group ( COOH), a hydrogenatom, and a variable side chain, R. The side chains range from a single hydro-gen atom to a complex double-ring structure. Examine the different side chainsof the amino acids shown in Figure 24-1. Identify the nonpolar alkanes, polarhydroxyl groups, acidic and basic groups such as carboxyl and amino groups,aromatic rings, and sulfur-containing groups. This wide range of side chainsgives the different amino acids a large variety of chemical and physical prop-erties and is an important reason why proteins can carry out so many differentfunctions.

    Twenty different amino acids are commonly found in the proteins of liv-ing things. The name of each amino acid and its three-letter abbreviation arelisted in Table 24-1. What is the abbreviation for glycine?

    The peptide bond The amino and carboxyl groups provide convenientbonding sites for linking amino acids together. Since an amino acid is bothan amine and a carboxylic acid, two amino acids can combine to form an

    Figure 24-1

    A large variety of side chains canbe found on amino acids. Someof them are shown on these rep-resentative amino acids and arehighlighted in green.

    Amino acid plus yields

    Peptide bond

    plus

    H R1

    H OH

    N C C OH

    Amino acid

    H R2

    H OH

    N C C OH

    Dipeptide Water

    H HR1

    H OH

    N C C N C C OH

    OH

    R2

    0 H2O

    776 Chapter 24 The Chemistry of Life

    R

    Amino group Carboxyl group

    Variable side chain

    Hydrogen atom H O

    H2N C C OH

    Glycine Serine Cysteine Lysine

    Glutamic acid Glutamine Valine Phenylalanine

    H2N C C OH

    H

    H

    O

    H2N C C OH

    CH2

    OH

    H

    O

    H2N C C OH

    CH2

    SH

    H

    O

    H2N C C OH

    CH2

    CH2

    CH2 NH2

    CH2

    H

    O

    H2N C C OH

    CH3

    H

    O

    H2N C C OH

    CH2

    H2N C C OH

    H

    O

    O OH

    CH2

    CH2

    C

    H2N C C OH

    H

    O

    CH3CH2

    CH2

    CH

    O NH2C

    H

    O

    Figure 24-2

    The amino group of one aminoacid bonds to the carboxylgroup of another amino acid toform a dipeptide. The organicfunctional group formed is anamide linkage and is called apeptide bond.

  • amide, releasing water in the process. This reaction is a condensation reaction.As Figure 24-2 shows, the amino group of one amino acid reacts with thecarboxyl group of another amino acid to form an amide functional group.Where do the H and OH that form water come from?

    The amide bond that joins two amino acids is referred to by biochemistsas a peptide bond.

    A molecule that consists of two amino acids bound together by a peptidebond is called a dipeptide. Figure 24-3a shows the structure of a dipeptidethat is formed from the amino acids glycine (Gly) and phenylalanine (Phe).Figure 24-3b shows a different dipeptide, also formed by linking togetherglycine and phenylalanine. Is Gly-Phe the same compound as Phe-Gly? No,theyre different. Examine these two dipeptides to see that the order in whichamino acids are linked in a dipeptide is important.

    Each end of the two-amino-acid unit in a dipeptide still has a free groupone end has a free amino group and the other end has a free carboxyl group.Each of those groups can be linked to the opposite end of yet another aminoacid, forming more peptide bonds. A chain of two or more amino acids linkedtogether by peptide bonds is called a peptide. Living cells always build pep-tides by adding amino acids to the carboxyl end of a growing chain.

    Polypeptides As peptide chains increase in length, other ways of referringto them become necessary. A chain of ten or more amino acids joined by pep-tide bonds is referred to as a polypeptide. When a chain reaches a length ofabout 50 amino acids, its called a protein.

    Because there are only 20 different amino acids that form proteins, itmight seem reasonable to think that only a limited number of different pro-tein structures are possible. But a protein can have from 50 to a thousand ormore amino acids, arranged in any possible sequence. To calculate the num-ber of possible sequences these amino acids can have, you need to considerthat each position on the chain can have any of 20 possible amino acids. Fora peptide that contains n amino acids, there are 20n possible sequences of theamino acids. So a dipeptide, with only two amino acids, can have 202, or400, different possible amino acid sequences. Even the smallest protein con-taining only 50 amino acids has 2050, or more than 1 1065, possiblearrangements of amino acids! It is estimated that human cells make between80 000 and 100 000 different proteins. You can see that this is only a verysmall fraction of the total number of proteins possible.

    H

    Peptide bond

    O

    C N

    24.1 Proteins 777

    The 20 Amino Acids

    Amino acid Abbreviation

    Alanine AlaArginine ArgAsparagine AsnAspartic acid AspCysteine CysGlutamic acid GluGlutamine GlnGlycine GlyHistidine HisIsoleucine IleLeucine LeuLysine LysMethionine MetPhenylalanine PheProline ProSerine SerThreonine ThrTryptophan TrpTyrosine TyrValine Val

    Table 24-1

    Glycylphenylalanine (Gly-Phe)Gly Phe

    Phenylalanylglycine (Phe-Gly)Phe Gly

    H HH

    H OH

    N C C N C C OH

    OH

    CH2

    H H

    H OH

    N C C N C C OH

    OH

    H

    CH2

    Figure 24-3

    Glycine and phenylalaninecan be combined in this configuration.

    Glycine and phenylalaninecan also be combined in thisconfiguration. Why are thesetwo structures different substances?

    b

    a

    a b

  • Figure 24-4

    The folding of polypeptidechains into both helices (left)and sheets (right) involvesamino acids that are fairly closetogether in the chain being heldin position by hydrogen bonds.Other interactions among thevarious side chains are notshown here but play an impor-tant role in determining thethree-dimensional shape of apolypeptide.

    Three-dimensional protein structure Long chains of amino acids start tofold into unique three-dimensional shapes even before they are fully synthe-sized, as intermolecular attractions form among the amino acids. Some areasof a polypeptide may twirl into helices, shaped like the coils on a telephonecord. Other areas may bend back and forth again and again into a sheet struc-ture, like the folds of an accordion. A polypeptide chain may also turn back onitself and change direction. A given protein may have several helices, sheets,and turns, or none at all. Figure 24-4 shows the folding patterns of a typicalhelix and a sheet. The overall three-dimensional shape of many proteins isglobular, or shaped like an irregular sphere. Other proteins have a long fibrousshape. The three-dimensional shape is determined by the interactions amongthe amino acids.

    Changes in temperature, ionic strength, pH, and other factors can act todisrupt these interactions, resulting in the unfolding and uncoiling of a pro-tein. Denaturation is the process in which a proteins natural three-dimen-sional structure is disrupted. Cooking often denatures the proteins in foods.When an egg is hard-boiled, the protein-rich egg white solidifies due to thedenaturation of its protein. Because proteins function properly only whenfolded, denatured proteins generally are inactive.

    The Many Functions of ProteinsProteins play many roles in living cells. They are involved in catalyzing reac-tions, transporting substances, regulating cellular processes, forming struc-tures, digesting foods, recycling wastes, and even serving as an energy sourcewhen other sources are scarce. See the Everyday Chemistry feature at theend of this chapter to learn how proteins play a role in the sense of smell.

    Enzymes In most organisms, the largest number of different proteins func-tion as enzymes, catalyzing the many reactions that go on in living cells. Anenzyme is a biological catalyst. Recall that a catalyst speeds up a chemicalreaction without being consumed in the reaction. A catalyst usually lowersthe activation energy of a reaction by stabilizing the transition state.

    How do enzymes function? The term substrate is used to refer to a reac-tant in an enzyme-catalyzed reaction. Substrates bind to specific sites onenzyme molecules, usually pockets or crevices. The pocket to which the sub-strates bind is called the active site of the enzyme. After the substrates bindto the active site, the active site changes shape slightly to fit more tightlyaround the substrates. This recognition process is called induced fit. In thediagram in Figure 24-5, youll see that the shapes of the substrates must fit

    778 Chapter 24 The Chemistry of Life

    Hydrogenbonds

    Helix

    Pleated sheet

    N

    NN

    N

    CC

    CC

    CC

    C

    H

    H

    H

    O

    O

    O

    H

    O

    C N

    NN

    N

    CC

    CC

    CC

    C

    H

    H

    H

    O

    O

    O

    H

    O

    C C CN

    NN

    N

    CC

    CC

    CC

    C

    H

    H

    H

    O

    O

    O

    H

    O

    N

    NN

    N

    CC

    CC

    CC

    C

    H

    H

    H

    O

    O

    O

    H

    O

    HCC

    CC

    C

    CC

    N

    N

    O

    HHN

    HN O

    O

    CC NH

    O

    CO

    HCC

    CC

    C

    CC

    N

    N

    O

    HHN

    HN O

    O

    CO

    HCC

    CC N OHN O

  • that of the active site, in the same way that puzzle pieces or a lock and key fittogether. A molecule only slightly different in shape from an enzymes nor-mal substrate doesnt bind as well to the active site or undergo the catalyzedreaction.

    The structure that forms when substrates are bound to an enzyme is calledan enzyme-substrate complex. The large size of enzyme molecules allowsthem to form multiple bonds with their substrates, and the large variety ofamino acid side chains in the enzyme allows a number of different intermol-ecular forces to form. These intermolecular forces lower the activation ener-gy needed for the reaction in which bonds are broken and the substrates areconverted to product.

    An example of an enzyme you may have used is papain, found in papayas,pineapple, and other plant sources. This enzyme catalyzes a reaction thatbreaks down protein molecules into free amino acids. Papain is the activeingredient in many meat tenderizers. When you sprinkle the dried form ofpapain on moist meat, you activate the papain so that it breaks down thetough protein fibers in the meat, making the meat more tender.

    Transport proteins Some proteins are involved in transporting smallermolecules throughout the body. The protein hemoglobin, modeled inFigure 24-6, carries oxygen in the blood, from your lungs to the rest of yourbody. Other proteins combine with biological molecules called lipids to trans-port them from one part of your body to another through the bloodstream. Youwill learn about lipids later in this chapter.

    24.1 Proteins 779

    Figure 24-5

    Substrates are brought closetogether as they fit into theuniquely shaped active site of anenzyme. The enzyme thenchanges shape as it moldsitself to the substrates, formingan enzyme-substrate complex.Bonds are broken and newbonds form to produce theproduct in the reaction.

    Figure 24-6

    Hemoglobin is a globularprotein with four polypeptidechains. The red structure in eachchain is heme, an organic groupcontaining an iron ion to whichoxygen binds.

    The pink skin of this pig isdue to the hemoglobin in itsblood.

    b

    a

    Enzyme

    Substrates

    Enzyme-substratecomplex

    Enzyme unchanged

    Product

    Active site

    Heme

    a b

  • Structural proteins The sole function of some proteins is to form struc-tures vital to organisms. These molecules are known as structural proteins.The most abundant structural protein in most animals is collagen, which ispart of skin, ligaments, tendons, and bones. Figure 24-7 shows the structureof collagen. Other structural proteins make up hair, fur, wool, hooves, fin-gernails, cocoons, and feathers.

    Hormones Hormones are messenger molecules that carry signals from onepart of the body to another. Some hormones are proteins. Insulin, a familiarexample, is a small (51 amino acids) protein hormone made by cells in thepancreas. When insulin is released into the bloodstream, it signals body cellsthat blood sugar is abundant and should be stored. A lack of insulin resultsin diabetes, a disease in which there is too much sugar in the bloodstream.Another protein hormone, chorionic gonadotropin, is synthesized by a devel-oping embryo. Release of this hormone causes the development of a placen-ta that nourishes the embryo.

    Because modern technology has made possible the laboratory synthesis ofproteins, some protein hormones are being synthetically produced for use asmedicines. Insulin, thyroid hormones, and growth hormones are some exam-ples. Both natural and synthetic proteins are used in a variety of productsfrom meat tenderizer to cleaning solutions to health and beauty aids.

    780 Chapter 24 The Chemistry of Life

    Figure 24-7

    Collagen is a fibrous protein thatconsists of three helical polypep-tides (right) that are coiledaround one another to form thestrong fibers of connective tissue(left). The large ropelike struc-tures in the photo are bundles ofcollagen fibers, held together bycross-linkage. Collagen is anextremely large protein. Each ofthe three strands is about 1000amino acids long.

    Section 24.1 Assessment

    1. Compare the structures of amino acids, dipeptides,polypeptides, and proteins. Which has the largestmolecular mass? The smallest?

    2. Draw the structure of the dipeptide Gly-Ser, cir-cling the peptide bond.

    3. List four functions that different proteins have inliving organisms.

    4. Thinking Critically How do the properties of pro-teins make them such useful catalysts? How dothey differ from other catalysts you have studied?

    5. Applying Concepts Identify an amino acid fromFigure 24-1 that can be classified into each of thecategories in the following pairs.

    a. nonpolar versus polarb. aromatic versus aliphaticc. acidic versus basic

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  • 24.2 Carbohydrates 781

    Objectives Describe the structures of

    monosaccharides, disaccha-rides, and polysaccharides.

    Explain the functions of car-bohydrates in living things.

    Vocabularycarbohydratemonosaccharidedisaccharidepolysaccharide

    Section Carbohydrates

    Analyzing the term carbohydrate offers a hint about the structure of thisgroup of molecules. Early observations that these compounds have the gen-eral chemical formula Cn(H2O)n and appear to be hydrates of carbon led totheir being called carbohydrates. Although it is now known that there are nofull water molecules attached to carbohydrates, the name has stayed.

    Kinds of CarbohydratesWhy do marathon runners eat large quantities of pasta before a big race?Pasta, as well as milk, fruit, bread, and potatoes, is rich in carbohydrates. Themain function of carbohydrates in living organisms is as a source of energy,both immediate and stored. Carbohydrates are compounds that contain mul-tiple hydroxyl groups ( OH) as well as a carbonyl functional group(CO). These molecules range in size from single monomers to polymersmade of hundreds or thousands of monomer units.

    Monosaccharides The simplest carbohydrates, often called simple sugars,are monosaccharides. The most common monosaccharides have either fiveor six carbon atoms. They have a carbonyl group on one carbon and hydrox-yl groups on most of the other carbons. The presence of a carbonyl groupmakes these compounds either aldehydes or ketones, depending upon thelocation of the carbonyl group. Multiple polar groups make monosaccharideswater soluble and give them high melting points.

    Glucose is a six-carbon sugar that has an aldehyde structure. Glucose ispresent in high concentration in blood because it serves as the major source ofimmediate energy in the body. For this reason, glucose is often called bloodsugar. Closely related to glucose is galactose, which differs only in how ahydrogen and a hydroxyl group are oriented in space around one of the six car-bon atoms. As you recall from Chapter 22, this relationship makes glucose andgalactose stereoisomers; that is, their atoms are arranged differently in space.Fructose, also known as fruit sugar because it is the major carbohydrate inmost fruits, is a six-carbon monosaccharide that has a ketone structure.Fructose is a structural isomer of glucose.

    When monosaccharides are in aqueous solution, they exist in both open-chain and cyclic structures. The cyclic structures are more stable and are thepredominant form of monosaccharides at equilibrium. Note in Figure 24-8that the carbonyl groups are present only in the open-chain structures. In thecyclic structures, they are converted to hydroxyl groups.

    24.2

    Cyclic form Open-chain form

    H OH

    H

    HO H

    OH

    OH

    CH2OH

    H CC

    C O

    C C

    Galactose

    Cyclic form Open-chain form OH H

    HOH HO

    O

    CC

    C C

    CH2OH

    CH2OH

    H

    Fructose

    H

    H C OH

    C O

    HC OH

    H

    3

    H

    C

    HC OH

    O

    HCOH

    HCOH

    H

    3

    Cyclic form Open-chain form

    H

    H

    OH

    HO

    H H

    OHOH

    CH2OH

    H CC

    C O

    C C

    Glucose

    H

    C

    HC OH

    O

    HCOH

    HOC H HOC H HOC H

    HC OH

    HC OH

    HOC H

    HCOH

    HCOH

    H

    3

    Figure 24-8

    Glucose, galactose, and fructoseare monosaccharides. In aqueoussolutions, they exist in an equi-librium between their open-chain and cyclic forms, which areinterconverted rapidly.

  • Disaccharides Like amino acids, monosaccharides can be linked togetherby a condensation reaction in which water is released. When two monosac-charides bond together, a disaccharide is formed. See Figure 24-9. The newbond formed is an ether functional group (C O C). Where does thewater that is produced in this reaction come from?

    One common disaccharide is sucrose, which is also known as table sugarbecause sucrose is used mainly as a sweetener. Sucrose is formed by linkingglucose and fructose. Another common disaccharide is lactose, the mostimportant carbohydrate in milk. It often is called milk sugar. Lactose isformed when glucose and galactose bond together. Some foods that containcommon disaccharides are shown in Figure 24-10a.

    Disaccharides are too large to be absorbed into the bloodstream from thehuman digestive system, so they must first be broken down into monosac-charides. This is accomplished by a number of enzymes in the digestive sys-tem, one of which is sucrase in the small intestine. Sucrase breaks downsucrose into glucose and fructose. Another enzyme, called lactase, breaksdown lactose into glucose and galactose. Some people do not have an activeform of the enzyme lactase. Unless they ingest lactase enzyme along withfoods that contain milk, they experience gas, bloating, and much discomfortas lactose accumulates in their digestive systems. These people are said to belactose intolerant.

    Polysaccharides You may have seen large carbohydrate polymers referredto as complex carbohydrates in nutritional references. Another name for acomplex carbohydrate is polysaccharide, which is a polymer of simple sugarsthat contains 12 or more monomer units. The same type of bond that joins twomonosaccharides in a disaccharide links them together in a polysaccharide.Pasta is a good source of polysaccharides. The pasta shown in Figure 24-10bcontains large amounts of starch, a polysaccharide from plants.

    782 Chapter 24 The Chemistry of Life

    Figure 24-9

    When glucose and fructose bondtogether, the disaccharidesucrose is formed. Note thatwater also is a product of thiscondensation reaction.Remember that each ringstructure is made of carbonatoms, which are not shown forsimplicity.

    OH

    CH2OH CH2OH

    HO

    Glucose

    OHO

    HO 0

    OH

    HO

    CH2OH

    Fructose

    O

    OHO

    CH2OH CH2OH

    HO

    OHO

    OHCH2OH

    H2O

    Sucrose Water

    O

    HO

    O H

    Figure 24-10

    When you have a snack ofmilk and cookies, you are ingest-ing the disaccharides lactose andsucrose.

    Pasta is rich in the polysac-charide starch.b

    a

    a b

    LAB

    See page 963 in Appendix E forModeling Sugars

  • Three important polysaccharides are starch, cellulose, and glycogen. Allare composed solely of glucose monomers, as Figure 24-11 illustrates.However, thats their only similarity, as all three have different propertiesand functions. Plants make both starch and cellulose. Starch is a soft, water-soluble molecule used to store energy, whereas cellulose is a water-insolublepolymer that forms rigid plant cell walls such as those found in wood.Glycogen is the animal counterpart of starch. It is made by animals to storeenergy, mostly in the liver and muscles.

    How can these three polymers all be made solely of glucose monomersyet have such different properties? The answer lies in the way the bonds thatlink the monomers together are oriented in space. Because of this differencein bond shape, humans can digest starch but not cellulose. Digestiveenzymes cant fit cellulose into their active sites due to the specific lock-and-key fit needed for enzyme action. As a result, the cellulose in the fruits, veg-etables, and grains that we eat is labeled dietary fiber because it passesthrough the digestive system largely unchanged.

    Glycogen

    Glucosesubunit

    Glucosesubunit

    Starch

    Cellulose

    Crosslink bond

    Glucose subunit

    24.2 Carbohydrates 783

    Figure 24-11

    The starch in potatoes, the cellu-lose in lettuce leaves, and theglycogen in meat are all poly-mers of glucose. Cellulose has alinear, unbranched structurethat resembles a chain-linkfence. Starch molecules can beeither branched or unbranched,and glycogen is highly branched.

    Section 24.2 Assessment

    6. Compare the structures of monosaccharides, disac-charides, and polysaccharides. Which has thelargest molecular mass? The smallest?

    7. What is the main function of carbohydrates in liv-ing organisms?

    8. Compare and contrast the structures of starch andcellulose. How do the structural differences affectour ability to digest these two polysaccharides?

    9. Thinking Critically If a carbohydrate has 2n

    possible isomers, where n is equal to the number ofcarbon atoms in the carbohydrate structure that are

    chiral (meaning a carbon atom with four differentgroups bonded to it), calculate the number ofpossible isomers for each of the following mono-saccharides. Use Figure 24-8 to help you.

    a. galactoseb. glucosec. fructose

    10. Interpreting Scientific Illustrations Drawthe structure of the disaccharide sucrose, circlingthe ether functional group that bonds the monomersugars together.

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  • Section 24.3 Lipids

    Objectives Describe the structures of

    fatty acids, triglycerides,phospholipids, and steroids.

    Explain the functions oflipids in living organisms.

    Identify some reactions thatfatty acids undergo.

    Relate the structure andfunction of cell membranes.

    Vocabularylipidfatty acidtriglyceridesaponificationphospholipidwaxsteroid

    The wax that you use to polish your car, the fat that drips out of your burg-er, and the vitamin D that fortifies the milk you drank for lunchwhat dothese diverse compounds have in common? They are all lipids.

    What is a lipid?A lipid is a large, nonpolar, biological molecule. Because lipids are nonpo-lar, they are insoluble in water. Lipids have two major functions in livingorganisms. They store energy efficiently, and they make up most of the struc-ture of cell membranes. Unlike proteins and carbohydrates, lipids are notpolymers with repeated monomer subunits.

    Fatty acids Although lipids are not polymers, many lipids have a majorbuilding block in common. This building block is the fatty acid, a long-chain carboxylic acid. Most naturally occurring fatty acids contain between12 and 24 carbon atoms. Their structure can be represented by the formula

    Most fatty acids have an even number of carbon atoms, which is a result oftheir being constructed two carbons at a time in enzymatic reactions.

    Fatty acids can be grouped into two main categories depending on the pres-ence or absence of double bonds between carbon atoms. Fatty acids that con-tain no double bonds are referred to as saturated. Those that have one or moredouble bonds are called unsaturated. Figure 24-12 shows the structures of twocommon fatty acids. Stearic acid is an 18-carbon saturated fatty acid; oleic acidis an 18-carbon unsaturated fatty acid. What makes oleic acid unsaturated?

    CH3(CH2)nCOOH

    Stearic acid Oleic acidHO O

    CH2

    C

    CH2

    CH2

    CH2

    CH2

    CH2

    CH2

    CH2

    CH2

    CH2

    CH2

    CH2

    CH2

    CH2

    CH2

    CH2

    CH3

    HO O

    CH2

    C

    CH2

    CH2

    CH2

    CH2

    CH2

    CH2

    CH

    CH

    CH2

    CH2

    CH2

    CH2

    CH2

    CH2

    CH2

    CH3

    Figure 24-12

    Two fatty acids abundant in ourdiets are the 18-carbon saturatedstearic acid and the 18-carbonunsaturated oleic acid. How isthe structure of the moleculeaffected by the presence of adouble bond? Refer to Table C-1in Appendix C for a key to atomcolor conventions.

    784 Chapter 24 The Chemistry of Life

  • An unsaturated fatty acid can become saturated if it reacts with hydrogen.As you learned in Chapter 23, hydrogenation is an addition reaction in whichhydrogen gas reacts with carbon atoms that are linked by multiple bonds.Each unsaturated carbon atom can pick up one hydrogen atom to become sat-urated. For example, oleic acid can be hydrogenated to form stearic acid.

    The double bonds in naturally occurring fatty acids are almost all in the cisgeometric isomer form. Recall from Chapter 22 that the cis isomer has identi-cal groups oriented on the same side of the molecule around a double bond.Because of the cis orientation, unsaturated fatty acids have a kink, or bend, intheir structure that prevents them from packing together. They dont form asmany intermolecular attractions as saturated fatty acid molecules. As a result,unsaturated fatty acids have lower melting points.

    Triglycerides Although fatty acids are abundant in living organisms, theyare rarely found alone. They most often are found bonded to glycerol, a mol-ecule with three carbons each containing a hydroxyl group. When three fattyacids are bonded to a glycerol backbone through ester bonds, a triglycerideis formed. The formation of a triglyceride is shown in Figure 24-13.

    Triglycerides can be either solids or liquids at room temperature. If liquid,they are usually called oils. If solid at room temperature, theyre called fats.Most mixtures of triglycerides from plant sources, such as corn, olive, andpeanut oils, are liquids because the triglycerides contain unsaturated fattyacids that have fairly low melting points. Animal fats, such as butter, containa larger proportion of saturated fatty acids. They have higher melting pointsand usually are solids at room temperature.

    Fatty acids are stored in fat cells of your body as triglycerides. Whenenergy is abundant, fat cells store the excess energy in the fatty acids oftriglycerides. When energy is scarce, the cells break down the triglycerides,forming free fatty acids and glycerol. Further breakdown of the fatty acidsreleases the energy used to form them. Although enzymes break downtriglycerides in living cells, the reaction can be duplicated outside of cellsby using a strong base such as sodium hydroxide. This reactionthehydrolysis of a triglyceride using an aqueous solution of a strong base toform carboxylate salts and glycerolis saponification, shown below.

    24.3 Lipids 785

    Figure 24-13

    Ester bonds in a triglyceride areformed when the hydroxylgroups of glycerol combine withthe carboxyl groups of the fattyacids.

    CH2OH

    CHOH

    CH2OH

    HO C(CH2)14CH3

    HOC(CH2)16CH3

    HOC(CH2)18CH3

    Glycerol 3 Fatty acids A triglyceride Water

    O

    0

    O

    O

    O

    CH O C (CH2)16 CH3 3H2O

    O

    CH2 O C (CH2)14 CH3

    O

    CH2 O C (CH2)18 CH3

    Triglyceride Glycerol A soapA base

    O

    O

    CH O C (CH2)14CH3 3NaOH 0 CHOH 3CH3(CH2)14 C ONa

    O

    O

    CH2 O C (CH2)14CH3

    CH2 O C (CH2)14CH3 CH2OH

    CH2OH

    BiologyCONNECTION

    The venom of poisonous snakescontains a class of enzymesknown as phospholipases. Theseenzymes catalyze the breakdownof phospholipids, triglycerides inwhich one fatty acid has beenreplaced by a phosphate group.The venom of the eastern dia-mondback rattlesnake contains aphospholipase that hydrolyzesthe ester bond at the middle carbon of phospholipids. If thelarger of the two breakdownproducts of this reaction gets intothe bloodstream, it dissolves themembranes of red blood cells,causing them to rupture. A bitefrom the eastern diamondbackcan lead to death if not treatedimmediately.

  • A Saponification ReactionApplying Concepts The reaction between atriglyceride and a strong base such as sodiumhydroxide is called saponification. In this reac-tion, the ester bonds in the triglyceride arehydrolyzed by the base. The sodium salts of thefatty acids, called soaps, precipitate out, and glyc-erol is left in solution.

    Materials solid vegetable shortening, 250-mLbeaker, 600-mL beaker, 6.0M NaOH, ethanol,saturated NaCl solution, stirring rod, hot plate,tongs, 25-mL graduated cylinder, evaporatingdish, cheesecloth (20 cm 20 cm), funnel

    Procedure

    1. Place a 250-mL beaker on the hot plate. Add25 g solid vegetable shortening to the beaker.Turn the hot plate on at a medium setting.

    2. As the vegetable shortening melts, slowly add12 mL ethanol and then 5 mL 6.0M NaOH tothe beaker. CAUTION: Ethanol is flammable.NaOH causes skin burns. Wear gloves.

    3. Heat the mixture, stirring occasionally, forabout 15 minutes, but do not allow it to boil.

    4. When the mixture begins to thicken, use tongsto remove the beaker from the heat. Allowthe beaker to cool for five minutes, then placeit in a cold water bath in the 600-mL beaker.

    5. Add 25 mL saturated NaCl solution to the mix-ture in the beaker. The soap is not very solubleand will appear as small clumps.

    6. Collect the solid soap clumps by filtering themthrough a cheesecloth-lined funnel.

    7. Using gloved hands, press the soap into anevaporating dish. Allow the soap to air dry forone or two days.

    8. Remove your gloves and wash your hands.

    Analysis1. What type of bonds present in the triglycerides

    are broken during the saponification reaction?

    2. What is the common name for the sodium saltof a fatty acid?

    3. How does soap remove dirt from a surface?4. Write a word equation for the saponification

    reaction in this lab.

    miniLAB

    Saponification is used to make soaps, which usually are the sodium salts offatty acids. A soap has both a polar end and a nonpolar end. Soaps can beused to clean nonpolar dirt and oil with water because the nonpolar dirt andoil bond to the nonpolar end of the soap molecules, and the polar end of thesoap molecules is soluble in water. Thus, the dirt-laden soap molecules canbe rinsed away with the water. You can make soap by doing the miniLABon this page.

    Phospholipids Another important type of triglyceride, phospholipids, arefound in greatest abundance in cellular membranes. A phospholipid is atriglyceride in which one of the fatty acids is replaced by a polar phosphategroup. As you can see in Figure 24-14a, the polar part of the molecule forms

    786 Chapter 24 The Chemistry of Life

    Figure 24-14

    A phospholipid has a polarhead and two nonpolar tails.

    The membranes of livingcells are formed by a doublelayer of lipids called a bilayer.The polar heads face out ofboth sides of the bilayer, wherethey are in contact with thewatery environment inside andoutside the cell. The nonpolartails point into the center of thebilayer.

    b

    a

    Polar head Nonpolar tails Polar heads Nonpolar tails

    a b

  • a head, and the nonpolar fatty acids look like tails. How are the polar andnonpolar parts of a phospholipid arranged in the membranes of cells? A typ-ical cell membrane has two layers of phospholipids, which are arranged withtheir nonpolar tails pointing inward and their polar heads pointing outward.See Figure 24-14b. This arrangement is called a lipid bilayer. Because thelipid bilayer structure acts as a barrier, the cell is able to regulate the materi-als that enter and leave through the membrane.

    Waxes Another type of lipid, waxes, also contain fatty acids. A wax is alipid that is formed by combining a fatty acid with a long-chain alcohol. Thegeneral structure of these soft, solid fats with low melting points is shownbelow, with x and y representing variable numbers of CH2 groups.

    Both plants and animals make waxes. Plant leaves are often coated withwax, which prevents water loss. Notice in Figure 24-15 how raindrops beadup on the leaves of a plant, indicating the presence of the waxy layer. Thehoneycomb of bees also is made of a wax, commonly called beeswax.Combining the 16-carbon fatty acid palmitic acid and a 30-carbon alcoholchain makes a common form of beeswax. Candles are sometimes made ofbeeswax because it burns slowly and evenly.

    Steroids Not all lipids contain fatty acid chains. Steroids are lipids thathave multiple cyclic rings in their structures. All steroids are built from thebasic four-ring steroid structure shown below.

    Some hormones, such as many sex hormones, are steroids that function toregulate metabolic processes. Cholesterol, another steroid, is an importantstructural component of cell membranes. Vitamin D also contains the four-ring steroid structure and plays a role in the formation of bones.

    24.3 Lipids 787

    Figure 24-15

    Plants produce wax that coatstheir leaves (top). The wax pro-tects the leaves from drying out.The honeycomb of a beehive isconstructed from beeswax(bottom).

    CH3(CH2)x C O (CH2)yCH3

    O

    Section 24.3 Assessment

    11. Write the equation for the complete hydrogenationof the polyunsaturated fatty acid linoleic acid,

    CH3(CH2)4CHCHCH2CHCH(CH2)7COOH.

    12. List an important function of each of these typesof lipids.

    a. triglycerides c. waxesb. phospholipids d. steroids

    13. Compare and contrast the structures of a steroid,a phospholipid, a wax, and a triglyceride.

    14. Thinking Critically What possible solvent canbe used to extract lipids from cell membranes?

    15. Interpreting Scientific Illustrations Draw thegeneral structure of a phospholipid. Label thepolar and nonpolar portions of the structure.

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  • Figure 24-16

    Nucleotides are the monomersfrom which nucleic acid polymersare formed.

    788 Chapter 24 The Chemistry of Life

    Section 24.4 Nucleic Acids

    Objectives Identify the structural com-

    ponents of nucleic acids.

    Relate the function of DNAto its structure.

    Describe the structure andfunction of RNA.

    Vocabularynucleic acidnucleotide

    Nucleic acids are the fourth class of biological molecules that you will study.They are the information-storage molecules of the cell. This group of nitro-gen-containing molecules got its name from the cellular location in whichthe molecules are primarily foundthe nucleus. It is from this control cen-ter of cells that nucleic acids carry out their major functions.

    Structure of Nucleic AcidsA nucleic acid is a nitrogen-containing biological polymer that is involved inthe storage and transmission of genetic information. The monomer thatmakes up a nucleic acid is called a nucleotide. Each nucleotide has threeparts: an inorganic phosphate group, a five-carbon monosaccharide sugar,and a nitrogen-containing structure called a nitrogen base. Examine each partof Figure 24-16a. Although the phosphate group is the same in allnucleotides, the sugar and the nitrogen base vary.

    In a nucleic acid, the sugar of one nucleotide is bonded to the phosphate ofanother nucleotide, as shown in Figure 24-16b. Thus, the nucleotides arestrung together in a chain, or strand, containing alternating sugar and phos-phate groups. Each sugar is also bonded to a nitrogen base that sticks out fromthe chain. The nitrogen bases on adjoining nucleotide units are stacked oneabove the other in a slightly askew position, much like the steps in a staircase.You can see this orientation in Figure 24-16c. Intermolecular forces hold eachnitrogen base close to the nitrogen bases above and below it.

    DNA: The Double HelixYouve probably heard of DNA (deoxyribonucleic acid), one of the twokinds of nucleic acids found in living cells. DNA contains the master plansfor building all the proteins in an organisms body.

    Each nucleotide contains a nitro-gen-containing base, a five-carbonsugar, and a phosphate group.

    a

    Sugar

    Nucleotide

    OH OH

    HHH H

    O

    HO

    HO P O CH2

    O

    CC

    C C

    C

    H

    N

    C NNH2

    C

    C

    H

    Phosphate group

    Nitrogen-containingbase

    Phosphate

    Sugar Base

    Base

    Base

    Base

    Phosphate

    Sugar

    Phosphate

    Sugar

    Phosphate

    Sugar

    O

    Nucleic acids are linearchains of alternating sugarsand phosphates. Attached toevery sugar is a nitrogen base,which is oriented roughly per-pendicular to the linear chain.

    b Nucleotides areoffset and thusresemble a staircase.

    c

  • 24.4 Nucleic Acids 789

    Figure 24-17

    The structure of DNA is a doublehelix that resembles a twistedzipper.

    H

    H......

    .....

    Deoxyribose

    Deoxyribose

    DeoxyriboseO

    O O

    CH3

    H

    H

    N

    H

    N

    N

    H

    NNH H......

    H.......

    Hydrogenbond

    O

    H

    H

    N

    ......H

    NN

    N

    N

    H

    N

    Thymine Adenine Cytosine Guanine

    N

    N

    Deoxyribose

    HN

    N

    N

    The structure of DNA The structure of DNA consists of two long chainsof nucleotides wound together to form a spiral structure. Each nucleotide inDNA contains a phosphate group, the five-carbon sugar deoxyribose, and anitrogen base. The alternating sugar and phosphate groups in each chainmake up the outside, or backbone, of the spiral structure. The nitrogen basesare on the inside. Because the spiral structure is composed of two chains, itis known as a double helix. You can see from Figure 24-17 that the DNAmolecule is similar to a zipper in which the two ends have been twisted inopposite directions. The two sugar-phosphate backbones form the outsidesof the zipper. What forms the zippers teeth?

    DNA contains four different nitrogen bases: adenine (A), thymine (T),cytosine (C), and guanine (G). As Figure 24-18 shows, both adenine and gua-nine contain a double ring. Thymine and cytosine are single-ring structures.Looking back at Figure 24-17, you can see that each nitrogen base on onestrand of the helix is oriented next to a nitrogen base on the opposite strand,in the same way that the teeth of a zipper are oriented. The side-by-side basepairs are close enough so that hydrogen bonds form between them. Becauseeach nitrogen base has a unique arrangement of organic functional groups thatcan form hydrogen bonds, the nitrogen bases always pair in a specific way sothat the optimum number of hydrogen bonds form. As Figure 24-18 shows,guanine always binds to cytosine, and adenine always binds to thymine. TheGC and AT pairs are called complementary base pairs.

    It is because of complementary base pairing that the amount of adenine ina molecule of DNA always equals the amount of thymine, and the amount ofcytosine always equals the amount of guanine. In 1953, James Watson andFrancis Crick used this observation to make one of the greatest scientific dis-coveries of the twentieth century when they determined the double-helixstructure of DNA. They accomplished this feat without actually carrying outmany laboratory experiments themselves. Instead, they analyzed and syn-thesized the work of numerous scientists who had carefully carried out stud-ies on DNA. The X-ray diffraction patterns of DNA fibers taken by MauriceWilkins and Rosalind Franklin were of special importance because theyclearly showed the dimensions of the DNA molecule and the molecules hel-ical structure. Watson and Crick used these results and molecular modelingtechniques to build their DNA structure with balls and sticks. This discoveryillustrates the importance of being able to visualize molecules in order touncover patterns in bonding arrangements. How might such molecular mod-eling be done today?

    The function of DNA Watson and Crick used their model to predict howDNAs chemical structure enables it to carry out its function. DNA storesthe genetic information of a cell in the cells nucleus. Before the celldivides, the DNA is copied so that the new generation of cells gets the same

    Figure 24-18

    In DNA, base pairing existsbetween a double-ringed baseand a single-ringed base.Adenine and thymine alwayspair, forming two hydrogenbonds between them. Guanineand cytosine always form threehydrogen bonds when they pair.

  • genetic information. Having determined that the two chains of the DNAhelix are complementary, Watson and Crick realized that complementarybase pairing provides a mechanism by which the genetic material of a cellis copied. The problem-solving LAB shows how DNA copies, or repli-cates, itself.

    The four nitrogen bases of DNA serve as the letters of the alphabet in theinformation-storage language of living cells. The specific sequence of theseletters represents an organisms master instructions, just as the sequence ofletters in the words of this sentence convey special meaning. The sequenceof bases is different in every species of organism, allowing for an enormousdiversity of life formsall from a language that uses only four letters. It isestimated that the DNA in a human cell has about three billion complemen-tary base pairs, arranged in a sequence unique to humans.

    790 Chapter 24 The Chemistry of Life

    problem-solving LAB

    How does DNA replicate?Formulating Models DNA must be copied, orreplicated, before a cell can divide so that each ofthe two new cells that are formed by cell divisionhas a complete set of genetic instructions. It is veryimportant that the replicating process be accurate;the new DNA molecules must be identical to theoriginal. Watson and Crick noticed that theirmodel for the three-dimensional structure of DNAprovided a mechanism for accurate replication.

    When DNA begins to replicate, the two nucle-otide strands start to unzip. An enzyme breaksthe hydrogen bonds between the nitrogen bases,and the strands separate to expose the nitrogenbases. Other enzymes deliver free nucleotidesfrom the surrounding medium to the exposednitrogen bases, adenine hydrogen-bonding withthymine and cytosine bonding with guanine.

    Thus, each strand builds a complementary strandby base pairing with free nucleotides. Thisprocess is shown in Diagram a. When the freenucleotides have been hydrogen-bonded intoplace, their sugars and phosphates bond cova-lently to those on adjacent nucleotides to formthe new backbone. Each strand of the originalDNA molecule is now bonded to a new strand.

    AnalysisDiagram b shows a small segment of a DNA mol-ecule. Copy the base sequence onto a clean sheetof paper, being careful not to make copyingerrors. Show the steps of replication to producetwo segments of the DNA.

    Thinking Critically1. How does the base sequence of a newly syn-

    thesized strand compare with the originalstrand to which it is bonded?

    2. If the original DNA segment is colored red andthe free nucleotides are colored blue, whatpattern of colors will the newly replicated DNAsegments have? Will all new segments havethe same color pattern? What does this pat-tern mean?

    3. What would happen if you had made an errorwhen copying the base sequence onto yoursheet of paper? How might an organism beaffected if this error had occurred during repli-cation of its DNA?

    A T C G G T T A A A C GT A G C C A A T T T G C

    C

    C

    C

    CC

    C

    TT

    T

    T

    TT

    T

    T

    T

    AA

    A

    A

    A

    ATA

    TA TA

    TAT A

    A

    A

    A

    G

    GG C G

    CG

    G

    GG

    a b

  • RNARNA (ribonucleic acid) also is a nucleic acid. Its general structure differsfrom that of DNA in three important ways. As you know, DNA contains thenitrogen bases adenine, cytosine, guanine, and thymine. RNA contains ade-nine, cytosine, guanine, and uracil; thymine is never found in RNA.Secondly, RNA contains the sugar ribose. DNA contains the sugar deoxyri-bose, which has a hydrogen atom in place of a hydroxyl group at one posi-tion. Compare these different structures shown in Figure 24-19.

    The third difference between DNA and RNA arises as a result of thesestructural differences. DNA is normally arranged in a double helix in whichhydrogen bonding links the two chains together through their bases. RNA isusually single stranded, with no such hydrogen bonds forming.

    Whereas DNA functions to store genetic information, RNA allows cells touse the information found in DNA. You have learned that the genetic infor-mation of a cell is contained in the sequence of nitrogen bases in the DNAmolecule. Cells use this base sequence to make RNA with a correspondingsequence. The RNA is then used to make proteins, each with an amino acidsequence that is determined by the order of nitrogen bases in RNA. A set ofthree of these nitrogen bases in RNA is called a codon. The sequences ofbases in these codons are referred to as the genetic code. Because proteinsare the molecular tools that actually carry out most activities in a cell, theDNA double helix is ultimately responsible for controlling the thousands ofchemical reactions that take place.

    24.4 Nucleic Acids 791

    H O

    Thymine

    O

    Uracil

    H

    N

    H HN

    O

    O

    H

    N

    N

    H

    H3C H

    Deoxyribose

    OH

    H H

    O

    H

    OH

    H

    HOCH2

    OH

    H H

    O

    H

    OH

    H

    HOCH2

    Ribose

    OHH

    Section 24.4 Assessment

    16. List the three chemical structures that make up anucleotide.

    17. Compare and contrast the structures and functionsof DNA and RNA.

    18. A sample of nucleic acid was determined to con-tain adenine, uracil, cytosine, and guanine. Whattype of nucleic acid is this?

    19. Thinking Critically Analyze the structure ofnucleic acids to determine what structural featuremakes them acidic.

    20. Predicting What is the genetic code? Predictwhat might happen to a protein if the DNA thatcoded for the protein contained the wrong basesequence.

    Figure 24-19

    DNA and RNA are nucleic acidswith some important differencesin structure. DNA containsthymine; RNA contains uracil,which lacks a methyl group.DNAs sugar, deoxyribose, has ahydrogen in one positioninstead of the hydroxyl groupthat ribose has.

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  • 792 Chapter 24 The Chemistry of Life

    Section 24.5 Metabolism

    Objectives Distinguish between

    anabolism and catabolism.

    Describe the role of ATP inmetabolism.

    Compare and contrast theprocesses of photosynthesis,cellular respiration, and fermentation.

    VocabularymetabolismcatabolismanabolismATPphotosynthesiscellular respirationfermentation

    Youve now studied the four major kinds of biological molecules and learnedthat they all are present in the food you eat. What happens to these moleculesafter they enter your body?

    Anabolism and CatabolismMany thousands of chemical reactions take place in the cells of a livingorganism. The set of reactions carried out by an organism is its metabolism.Why are so many reactions involved in metabolism? Living organisms mustaccomplish two major functions in order to survive. They have to extractenergy from nutrients in forms that they can use immediately as well as storefor future use. In addition, they have to use nutrients to make building blocksfor synthesizing all of the molecules needed to carry out their life functions.These processes are summarized in Figure 24-20.

    The term catabolism refers to the metabolic reactions that break downcomplex biological molecules such as proteins, polysaccharides, triglyc-erides, and nucleic acids for the purposes of forming smaller building blocksand extracting energy. After you eat a meal of spaghetti and meatballs, yourbody immediately begins to break down the starch polymer in the spaghettiinto glucose. The glucose is then broken down into smaller molecules in aseries of energy-releasing catabolic reactions. Meanwhile, the protein poly-mers in the meatballs are catabolized into amino acids.

    The term anabolism refers to the metabolic reactions that use energy andsmall building blocks to synthesize the complex molecules needed by anorganism. After your body has extracted the energy from the starch in pasta,it uses that energy and the amino-acid building blocks produced from themeat proteins to synthesize the specific proteins that allow your muscles tocontract, catalyze metabolic reactions, and carry out many other functionsin your body.

    Figure 24-20 shows the relationship between catabolism and anabolism.The simple building-block molecules that are listed on the right side of thediagram are used to build the complex molecules that are listed on the leftside of the diagram. As the arrow moves from right to left, anabolic reactions

    Figure 24-20

    A large number of differentmetabolic reactions take place inliving cells. Some involve break-ing down nutrients to extractenergy; these are catabolicprocesses. Others involve usingenergy to build large biologicalmolecules; these reactions areanabolic processes.

    Catabolism

    Anabolism

    Nucleic acids

    Triglycerides

    Polysaccharides

    Proteins

    Nucleotides

    Fatty acids

    Simple sugars

    Amino acids

    ADP PComplex molecules Building blocksATP

  • Figure 24-22

    These giant seaweeds, calledkelps, must grow close to theoceans surface where light isavailable for photosynthesis.They cannot grow in the darkdepths where sunlight does notpenetrate the seawater.

    take place. As the lower arrow moves from left to right, catabolic processestake place and the complex molecules are broken down into their smallerbuilding blocks.

    ATP Catabolism and anabolism are linked by common building blocks thatcatabolic reactions produce and anabolic reactions use. A common form ofpotential chemical energy also links the two processes. ATP (adenosine triphos-phate) is a nucleotide that functions as the universal energy-storage moleculein living cells. During catabolic reactions, cells harness the chemical energy offoods and store it in the bonds of ATP. When these bonds are broken, the chem-ical energy is released and used by cells to drive anabolic reactions that mightnot otherwise occur. Most cellular reactions have an efficiency of only about40 percent at best; the remaining 60 percent of the energy in food is lost asheat, which is used to keep your body warm.

    The structure of ATP is shown in Figure 24-21. During catabolic reac-tions, cells produce ATP by adding an inorganic phosphate group to thenucleotide adenosine diphosphate (ADP) in an endothermic reaction. Onemole of ATP stores approximately 30.5 kJ of energy under normal cellularconditions. During anabolism, the reverse reaction occurs. ATP is brokendown to form ADP and inorganic phosphate in an exothermic reaction.Approximately 30.5 kJ of energy is released from each mole of ATP.

    PhotosynthesisWhat is the source of the energy that fuels metabolism? For most livingthings, certain wavelengths of sunlight provide all of this energy. Some bac-teria and the cells of all plants and algae, including the brown algae shownin Figure 24-22, are able to capture light energy and convert some of it tochemical energy. Animals cant capture light energy, so they get energy byeating plants or by eating other animals that eat plants. The process that con-verts energy from sunlight to chemical energy in the bonds of carbohydratesis called photosynthesis. During the complex process of photosynthesis,carbon dioxide and water provide the carbon, hydrogen, and oxygen atomsthat make up carbohydrates and oxygen gas, which also is formed. The fol-lowing net reaction takes place during photosynthesis.

    6CO2 6H2O light energy 0 C6H12O6 6O2Carbon Water Glucose Oxygendioxide

    Photosynthesis results in the reduction of the carbon atoms in carbon diox-ide as glucose is formed. During this redox process, oxygen atoms in waterare oxidized to oxygen gas.

    24.5 Metabolism 793

    Figure 24-21

    ATP is a nucleotide that containsan adenine nitrogen base, aribose sugar, and three phos-phate groups. When the finalphosphate group is removedfrom ATP, as modeled by the reddotted line, ADP is formed andenergy is released.

    Ribose

    Triphosphate

    Adenine

    ATP

    P P P

  • Cellular RespirationMost organisms need oxygen to live. Oxygen that is produced during photo-synthesis is used by living things during cellular respiration, the process inwhich glucose is broken down to form carbon dioxide, water, and largeamounts of energy. Cellular respiration is the major energy-producingprocess in living organisms. Figure 24-23 shows one use of energy in thebody. This energy is stored in the bonds of ATP, and a maximum of 38 molesof ATP are produced for every mole of glucose that is catabolized. Cellularrespiration is a redox process; the carbon atoms in glucose are oxidized whileoxygen atoms in oxygen gas are reduced to the oxygen in water. The netreaction that takes place during cellular respiration is

    C6H12O6 6O2 0 6CO2 6H2O energyGlucose Oxygen Carbon Water

    dioxide

    Note that the net equation for cellular respiration is the reverse of the netequation for photosynthesis. You will learn in Chapter 26 how these twoprocesses complement each other in nature.

    FermentationDuring cellular respiration, glucose is completely oxidized, and oxygen gas isrequired to act as the oxidizing agent. Can cells extract energy from glucosein the absence of oxygen? Yes, but not nearly as efficiently. Without oxygen,only a fraction of the chemical energy of glucose can be released. Whereascellular respiration produces 38 moles of ATP for every mole of glucosecatabolized in the presence of oxygen, only two moles of ATP are producedper mole of glucose that is catabolized in the absence of oxygen. This pro-vides enough energy for oxygen-deprived cells so that they dont die. Theprocess in which glucose is broken down in the absence of oxygen is knownas fermentation. There are two common kinds of fermentation. In one,ethanol and carbon dioxide are produced. In the other, lactic acid is produced.

    Alcoholic fermentation Yeast and some bacteria can ferment glucose toproduce the alcohol ethanol.

    C6H12O6 0 2CH3CH2OH 2CO2 energyGlucose Ethanol Carbon

    dioxide

    794 Chapter 24 The Chemistry of Life

    Figure 24-23

    These runners will need largeamounts of energy if they are tocomplete the race. This energy isstored in the bonds of ATP intheir cells.

    Personal TrainerAre you interested in healthand fitness? Are you good atmotivating people to do theirbest? Then consider a career asa personal trainer.

    Personal trainers help peopleset up and follow exercise pro-grams. The trainers design theprograms to get specificresults, such as weight loss,muscle building, improvedendurance, or preparation fora sport. They can create pro-grams for people who areolder or injured. Trainers workin gyms, health clubs, and cor-porate fitness centers. The fre-quency with which trainers seea client varies according to theclients needs.

  • This reaction, called alcoholic fermentation, is important to certain segmentsof the food industry, as you can see in Figure 24-24. Alcoholic fermentationis needed to make bread dough rise, form tofu from soybeans, and producethe ethanol in alcoholic beverages. Another use of the ethanol that is pro-duced by yeast is as an additive to gasoline, called gasohol. You can observeyeast cells fermenting sugar in the CHEMLAB at the end of this chapter.

    Lactic acid fermentation Have you ever gotten muscle fatigue while run-ning a race? During strenuous activity, muscle cells often use oxygen fasterthan it can be supplied by the blood. When the supply of oxygen is depleted,cellular respiration stops. Although animal cells cant undergo alcoholic fer-mentation, they can produce lactic acid and a small amount of energy fromglucose through lactic acid fermentation.

    C6H12O6 0 2CH3CH(OH)COOH energyGlucose Lactic acid

    The lactic acid that is produced is moved from the muscles through the bloodto the liver. There, it is converted back into glucose that can be used in cata-bolic processes to yield more energy once oxygen becomes available.However, if lactic acid builds up in muscle cells at a faster rate than the bloodcan remove it, muscle fatigue results. Buildup of lactic acid is what causes aburning pain in the muscle during strenuous exercise.

    24.5 Metabolism 795

    Figure 24-24

    Bread dough is heavy beforeyeast cells begin to ferment thecarbohydrates (left). After fer-mentation has produced carbondioxide, the dough becomeslighter and fluffier as it rises(right).

    Section 24.5 Assessment

    21. Compare and contrast the processes of anabolismand catabolism.

    22. Explain the role ATP plays in the metabolism ofliving organisms.

    23. Decide whether each of the following processes isanabolic or catabolic.

    a. photosynthesisb. cellular respirationc. fermentation

    24. Thinking Critically Why is it necessary to usesealed casks when making wine?

    25. Calculating How many moles of ATP would ayeast cell produce if six moles of glucose wereoxidized completely in the presence of oxygen?How many moles of ATP would the yeast cellproduce from six moles of glucose if the cell weredeprived of oxygen? For more help, refer toArithmetic Operations in the Math Handbook onpage 887 of this textbook.

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    Topic: Forensic AnthropologyTo learn more about forensicanthropology, visit theChemistry Web site atchemistrymc.comActivity: Research forensicanthropology and explain atleast four ways that knowl-edge of the chemistry of lifehelps scientists learn aboutwhat ancient ice men andanimals did on their lastdays alive.

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  • 796 Chapter 24 The Chemistry of Life

    Pre-Lab

    1. Reread the section of this chapter that describesalcoholic fermentation.

    2. Write the chemical equation for the alcoholic fer-mentation of glucose.

    3. Read the entire CHEMLAB.

    4. Prepare all written materials that you will take intothe laboratory. Be sure to include safety precau-tions and procedure notes.

    5. Form a hypothesis about how the pressure insidethe test tube is related to the production of carbondioxide during the reaction. Refer to the ideal gaslaw in your explanation.

    6. Why is temperature control an essential feature ofthe CHEMLAB?

    Procedure

    1. Load the ChemBio program into your graphingcalculator. Connect the CBL and calculator withthe link cable. Connect the pressure sensor to theCBL with a CBL-DIN cable.

    2. Prepare a water bath using the 600-mL beaker. Thebeaker should be about two-thirds full of water.The water temperature should be between 36Cand 38C.

    3. Set up the test tube, ring stand, and utility clamp asshown in the figure. Obtain about 3 mL yeast sus-pension in a 10-mL graduated cylinder, and pour itinto the test tube. Obtain about 3 mL 5% sucrosesolution in a 10-mL graduated cylinder. Add thesucrose solution to the yeast in the test tube. Stir tomix. Pour enough vegetable oil on top of the mix-ture to completely cover the surface.

    Safety Precautions Always wear safety goggles and an apron in the lab. Do not use the thermometer as a stirring rod.

    ProblemWhat is the rate of alcoholicfermentation of sugar bybakers yeast?

    Objectives Measure the pressure of

    carbon dioxide produced bythe alcoholic fermentationof sugar by yeast.

    Calculate the rate of pro-duction of carbon dioxideby the alcoholic fermenta-tion of sugar by yeast.

    MaterialsCBL systemgraphing calculatorChemBio programVernier pressure

    sensorlink cableCBL-DIN cabletest tube with #5

    rubber-stopperassembly

    5% sucrose solutionring stand

    stirring rod600-mL beakerthermometerbasting bulbhot and cold wateryeast suspensionvegetable oilutility clamp10-mL graduated

    cylinders (2)pipette

    Alcoholic Fermentation inYeastYeast cells are able to metabolize many types of sugars. In thisexperiment, you will observe the fermentation of sugar bybakers yeast. When yeast cells are mixed with a sucrose solution,they must first hydrolyze the sucrose to glucose and fructose. Thenthe glucose is broken down in the absence of oxygen to form ethanoland carbon dioxide. You can test for the production of carbon diox-ide by using a CBL pressure sensor to measure an increase in pressure.

    CHEMLAB CBL24

  • CHEMLAB 797

    4. Place the stopper assembly into the test tube. Makesure it has an airtight fit. Leave both valves of theassembly open to the atmosphere.

    5. While one lab partner does step 5, the other partnershould do steps 6 and 7. Lower the test tube into thewater bath and allow it to incubate for 10 minutes.Keep the temperature of the water bath between36C and 38C by adding small amounts of hot orcold water with the basting bulb as needed.

    6. Start the ChemBio program. Choose 1:SET UPPROBES under MAIN MENU. Choose 1 for num-ber of probes. Choose 3:PRESSURE underSELECT PROBE. Enter 1 for Channel. Choose1:USE STORED for CALIBRATION. Choose1:ATM for PRESSURE UNITS.

    7. Choose 2:COLLECT DATA under MAIN MENU.Choose 2:TIME GRAPH under DATA COLLEC-TION. Use time between sample seconds = 10.Use number of samples = 60. (This will give you600 seconds or 10 minutes of data). Choose 1:USETIME SETUP under CONTINUE? Set Ymin = 0.8,Ymax = 1.3, and Yscl = 0.1. Do not press ENTERuntil the test tube has finished incubating.

    8. After the test tube has incubated for ten minutes,close the valve attached to the stopper. Make surethe valve near the pressure sensor is open to thesensor. Start measuring the gas pressure by press-

    ing ENTER. Monitor the pressure reading on theCBL unit. If the pressure exceeds 1.3 atm, thestopper can pop off. Open the air valve on thepressure sensor to release this excess gas pressure.

    9. After ten minutes, the data collection will stop.Open the air valve on the stopper. If needed, youcan run a second trial by closing the air valve andchoosing 2:YES to REPEAT? If you are finished,press 1:NO.

    Cleanup and Disposal

    1. Rinse out and wash all items.

    2. Rinse the yeast suspension/sucrose/vegetable oilmixture down the sink with large amounts of water.

    3. Return all lab equipment to its proper place.

    Analyze and Conclude

    1. Making and Using Graphs Choose 3:VIEWGRAPH from the MAIN MENU. Make a sketchof the graph. (You also may want to record thedata table by using 4:VIEW DATA.)

    2. Interpreting Data The rate of carbon dioxideproduction by the yeast can be found by calculat-ing the slope of the graph. Return to the MAINMENU and choose 5:FIT CURVE. Choose 1:LIN-EAR L1, L2. The slope will be listed under LIN-EAR as A of Y = A*X + B. Record this value.

    3. Communicating How does your rate of carbondioxide production compare with the rates of othermembers of the class?

    4. Analyzing Why did you add vegetable oil to thetest tube in step 3?

    5. Suppose that the pressure doesnot change during a trial. What might be some pos-sible reasons for this?

    Real-World Chemistry

    1. Yeast is used in baking bread because the carbondioxide bubbles make the bread rise. The otherproduct of alcoholic fermentation is ethanol. Whycant you taste this alcohol when you eat bread?

    2. How would the appearance of a loaf of bread bedifferent if you used twice as much yeast as therecipe called for?

    Error Analysis

    CHAPTER 24 CHEMLAB

  • Sense of SmellTake a deep breath. What do you smell? Maybe itsthe eraser on your pencil, some flowers outsideyour window, an apple pie coming out of the oven,or even stinky gym shoes on the floor. Your senseof smell, otherwise known as olfaction, tells you alot about the world around you.

    Fitting InHow exactly do you smell odors? If you said thatyou smell with your nose, you are only partiallycorrect. The nose you see when you look in themirror doesnt actuallydetect odors. Its job is topull odor molecules, knownas odorants, into your nasalpassages when you breathe.

    The air you inhale carriesodorants to a small regionlocated high inside yournasal passage just below andbetween your eyes. The tis-sues of this region containnerve cells that have hairlikefibers called cilia on one end.When receptors located on the cilia are stimulatedby odorants, the nerve cells send messages to thebrain. The brain then identifies the odors you smell.

    The exact manner in which receptors detectodorants is not entirely understood. However,researchers have found evidence to suggest that itinvolves the shapes of both the receptors and theodorants. Receptors are usually large, globularprotein molecules that are similar in shape toenzymes. Their surfaces contain small crevices. Anodorant must fit into and bind with a crevice on thesurface of the receptor much as a substrate mole-cule fits into and binds with the active site on thesurface of an enzyme. Each type of receptor has auniquely shaped crevice on its surface that bindsonly with an odorant of a particular shape.

    Not By Shape AloneThe process of smelling is not that simple, how-ever. Scientists have discovered that shape is notthe only property that determines whether an odor-ant will bind with a receptor. Odorant moleculesmust be able to travel through air and they must beable to dissolve in the fluids of the nasal passages.In addition, some research suggests that odorreceptors can detect the energy levels of the odor-ants. An odorant with exactly the right energy will

    vibrate in such a way that itproduces a response in thereceptor. This may be whatcauses the nerve cell to senda signal to the brain.

    So Many OdorsHow many odors do youthink you can recognize? Ifyour olfactory system is atits best, you can distinguishabout 10 000 different odors.Does this mean that youhave more than 10 000 dif-

    ferent types of olfactory receptors? The answer isno. In fact, you have fewer than 1000 differenttypes of olfactory receptors.

    As researchers searched for an explanation ofhow the olfactory receptors recognize so manydifferent odors, they found that the olfactory sys-tem uses a combination of receptors for each odor.A single odorant can be recognized by more thanone receptor because different receptors respondto different parts of the same odorant molecule.Rather than responding to a signal from a singlereceptor for each odor, the brain interprets a com-bination of signals from several receptors in orderto identify a particular odor. In this way, a limitednumber of receptors can be used to identify a largenumber of odors.

    Everyday Chemistry

    1. Relating Concepts How is the receptor-odorant relationship similar to an enzyme-substrate relationship?

    2. Applying How might fragrance designersbenefit from an understanding of how theshape of an odorant stimulates a receptor?

    798 Chapter 24 The Chemistry of Life

  • Study Guide 799

    CHAPTER STUDY GUIDE24

    Vocabulary

    Summary24.1 Proteins Proteins are biological polymers made of amino

    acids that are linked together by peptide bonds.

    Protein chains fold into intricate three-dimensionalstructures.

    Many proteins function as enzymes, which are high-ly specific and powerful biological catalysts. Otherproteins function to transport important chemicalsubstances, or provide structure in organisms.

    24.2 Carbohydrates Monosaccharides, known as simple sugars, are alde-

    hydes or ketones that also have multiple hydroxylgroups.

    Bonding two simple sugars together forms a disac-charide such as sucrose or lactose.

    Polysaccharides such as starch, cellulose, and glyco-gen are polymers of simple sugars.

    Carbohydrates function in living things to provideimmediate and stored energy.

    24.3 Lipids Fatty acids are long-chain carboxylic acids that usu-

    ally have between 12 and 24 carbon atoms.

    Saturated fatty acids have no double bonds; unsatu-rated fatty acids have one or more double bonds.

    Fatty acids can be linked to glycerol backbones toform triglycerides.

    The membranes of living cells have a lipid bilayerstructure.

    Steroids are lipids that have a multiple-ring structure.

    24.4 Nucleic Acids Nucleic acids are polymers of nucleotides, which

    consist of a nitrogen base, a phosphate group, and asugar.

    DNA contains deoxyribose sugar and the nitrogenbases adenine, cytosine, guanine, and thymine.

    RNA contains ribose sugar and the nitrogen basesadenine, cytosine, guanine, and uracil.

    DNA functions to store the genetic information inliving cells and transmit it from one generation ofcells to the next. RNA functions in protein synthesis.

    24.5 Metabolism Metabolism is the sum of the many chemical reac-

    tions that go on in living cells.

    Catabolism refers to reactions that cells undergo toextract energy and chemical building blocks fromlarge biological molecules.

    Anabolism refers to the reactions through whichcells use energy and small building blocks to buildthe large biological molecules needed for cell struc-tures and for carrying out cell functions.

    During photosynthesis, cells use carbon dioxide,water, and light energy to produce carbohydratesand oxygen.

    During cellular respiration, cells break down carbo-hydrates in the presence of oxygen gas to producecarbon dioxide and water. Energy released is storedas chemical potential energy in the molecule ATP.

    In the absence of oxygen, cells can carry out eitheralcoholic or lactic acid fermentation.

    active site (p. 778) amino acid (p. 776) anabolism (p. 792) ATP (p. 793) carbohydrate (p. 781) catabolism (p. 792) cellular respiration (p. 794) denaturation (p. 778) disaccharide (p. 782) enzyme (p. 778)

    fatty acid (p. 784) fermentation (p. 794) lipid (p. 784) metabolism (p. 792) monosaccharide (p. 781) nucleic acid (p. 788) nucleotide (p. 788) peptide (p. 777) peptide bond (p. 777)

    phospholipid (p. 786) photosynthesis (p. 793) polysaccharide (p. 782) protein (p. 775) saponification (p. 785) steroid (p. 787) substrate (p. 778) triglyceride (p. 785) wax (p. 787)

    chemistrymc.com/vocabulary_puzzlemaker

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  • 800 Chapter 24 The Chemistry of Life

    Go to the Chemistry Web site atchemistrymc.com for additionalChapter 24 Assessment.

    Concept Mapping26. Complete the concept map using the following terms:

    lactic acid, ATP, cellular respiration, metabolism, alco-holic, fermentation.

    Mastering Concepts27. What should you call a chain of eight amino acids? A

    chain of 200 amino acids? (24.1)

    28. Name five parts of your body that are made of struc-tural proteins. (24.1)

    29. Describe two common shapes found in the three-dimensional folding of proteins. (24.1)

    30. Name the organic functional groups in the side chainsof the following amino acids. (24.1)

    a. glutamine c. glutamic acidb. serine d. lysine

    31. Explain how the active site of an enzyme functions.(24.1)

    32. Name the amino acids represented by each of the fol-lowing abbreviations. (24.1)

    a. Gly d. Pheb. Tyr e. Gluc. Trp f. His

    33. Name an amino acid that has an aromatic ring in itsside chain. (24.1)

    34. Name two nonpolar and two polar amino acids. (24.1)

    35. Is the dipeptide lysine-valine the same compound asthe dipeptide valine-lysine? Explain. (24.1)

    36. How do enzymes lower the activation energy for areaction? (24.1)

    37. The structure shown is tryptophan. Describe some ofthe properties you would expect tryptophan to have,based on its structure. In what class of large moleculesdo you think tryptophan is a building block? (24.1)

    38. Most proteins with a globular shape are oriented sothat they have mostly nonpolar amino acids on theinside and polar amino acids located on the outer sur-face. Does this make sense in terms of the nature ofthe cellular environment? Explain. (24.1)

    39. Classify the following carbohydrates as monosaccha-rides, disaccharides, or polysaccharides. (24.2)

    a. starch e. celluloseb. glucose f. glycogenc. sucrose g. fructosed. ribose h. lactose

    40. Name two isomers of glucose. (24.2)

    41. What kind of bond is formed when two monosaccha-rides combine to form a disaccharide? (24.2)

    42. Give a scientific term for each of the following. (24.2)

    a. blood sugar c. table sugarb. fruit sugar d. milk sugar

    43. Explain how the different bonding arrangements incellulose and starch give them such differentproperties. (24.2)

    44. The disaccharide maltose is formed from two glucosemonomers. Draw its structure. (24.2)

    45. Hydrolysis of cellulose, glycogen, and starch producesonly one monosaccharide. Why is this so? Whatmonosaccharide is produced? (24.2)

    46. Digestion of disaccharides and polysaccharides cannottake place in the absence of water. Why do you thinkthis is so? Include an equation in your answer. (24.2)

    47. Draw the structure of the open-chain form of fructose.Circle all chiral carbons, and then calculate the num-ber of stereoisomers with the same formula asfructose. (24.2)

    CHAPTER ASSESSMENT##CHAPTER ASSESSMENT24

    3. 4.

    1.

    by

    can be produced during

    6.5.

    2.

    O

    CH2

    H2N OH

    CC

    NHC

    H

    chemistrymc.com/chapter_test

    http://chemistrymc.comhttp://chemistrymc.com/chapter_test

  • Assessment 801

    CHAPTER 24 ASSESSMENT

    48. Compare and contrast the structures of a triglycerideand a phospholipid. (24.3)

    49. Predict whether a triglyceride from beef fat or atriglyceride from olive oil will have a higher meltingpoint. Explain your reasoning. (24.3)

    50. Explain how the structure of soaps makes them effec-tive cleaning agents. (24.3)

    51. Draw a portion of a lipid bilayer membrane, labelingthe polar and nonpolar parts of the membrane. (24.3)

    52. Where and in what form are fatty acids stored in thebody? (24.3)

    53. What type of lipid does not contain fatty acid chains?Why are these molecules classified as lipids? (24.3)

    54. Draw the structure of the soap sodium palmitate(palmitate is the conjugate base of the 16-carbon satu-rated fatty acid, palmitic acid) and label its polar andnonpolar ends. (24.3)

    55. What three structures make up a nucleotide? (24.4)

    56. Name two nucleic acids found in organisms. (24.4)

    57. Explain the roles of DNA and RNA in the productionof proteins. (24.4)

    58. Where in living cells is DNA found? (24.4)

    59. Describe the types of bonds and attractions that linkthe monomers together in a DNA molecule. (24.4)

    60. In the double helical structure of DNA, the base gua-nine is always bonded to cytosine and adenine isalways bonded to thymine. What do you expect to bethe relative proportional amounts of A, T, C, and G ina given length of DNA? (24.4)

    61. One strand in a DNA molecule has the following basesequence. What is the base sequence of the otherstrand in the DNA molecule? (24.4)

    C-C-G-T-G-G-A-C-A-T-T-A

    62. Is digestion an anabolic or a catabolic process?Explain. (24.5)

    63. Compare the net reactions for photosynthesis and cel-lular respiration with respect to reactants, products,and energy. (24.5)

    Mastering ProblemsProtein Structure (24.1)64. How many peptide bonds are present in a peptide that

    has five amino acids?

    65. How many peptides, each containing four differentamino acids, can be made from Phe, Lys, Pro, andAsp? List the peptides, using the three-letter abbrevia-tions for the amino acids.

    66. The average molecular mass of an amino acid is 110g/mol. Calculate the approximate number of amino acidsin a protein that has a molecular mass of 36 500 g/mol.

    Calculations with Lipids (24.3)67. The fatty acid palmitic acid has a density of 0.853

    g/mL at 62C. What will be the mass of a 0.886-Lsample of palmitic acid at that temperature?

    68. How many moles of hydrogen gas are required forcomplete hydrogenation of one mole of linolenic acid,whose structure is shown below? Write a balancedequation for the hydrogenation reaction.

    CH3CH2CHCHCH2CHCHCH2CHCH(CH2)7COOHLinolenic acid

    69. A chicken egg contains about 213 mg of cholesterol.Calculate how many moles of cholesterol this repre-sents if the molecular mass of cholesterol is 386 amu.

    70. Calculate the number of moles of sodium hydroxideneeded in the saponification of 16 moles of atriglyceride.

    Working with DNA (24.4)71. The genetic code is a triplet code, that is, a sequence

    of three bases in RNA codes for each amino acid in apeptide chain or protein. How many RNA bases arerequired to code for a protein that contains 577 aminoacids?

    72. It has been calculated that the average length of a basepair in a DNA double helix is 3.4 . The humangenome (the complete set of all DNA in the nucleus ofa human cell) contains about three billion base pairs ofDNA. In centimeters, how long is the DNA in thehuman genome? Assume that the DNA is stretched out and not coiled around proteins as it actually is in a living cell. (1 1010 m)

    73. A cell of the bacterium Escherichia coli has about 4.2 106 base pairs of DNA, whereas each humancell has about 3 109 base pairs of DNA. What per-centage of the size of the human genome does theE. coli DNA represent?

    Energy Calculations (24.5)74. Every mole of glucose that undergoes alcoholic fer-

    mentation in yeast results in the net synthesis of twomoles of ATP. How much energy in kJ is stored in twomoles of ATP? Assume 100% efficiency.

    75. How many moles of lactic acid are produced whenthree moles of glucose undergo fermentation in yourmuscle cells? Assume 100% completion of the process.

  • 802 Chapter 24 The Chemistry of Life

    76. The synthesis of one mole of the fatty acid palmiticacid from two-carbon building blocks requires sevenmoles of ATP. How many kJ of energy are required forthe synthesis of one mole of palmitic acid?

    77. How many grams of glucose can be oxidized completelyby 2.0 L of O2 gas at STP during cellular respiration?

    78. Calculate and compare the total energy in kJ that isconverted to ATP during the processes of cellular res-piration and fermentation.

    Mixed ReviewSharpen your problem-solving skills by answering thefollowing.

    79. Draw the carbonyl functional groups present in glu-cose and fructose. How are the groups similar? Howare they different?

    80. List the names of the monomers that make up pro-teins, complex carbohydrates, and nucleic acids.

    81. Describe the functions of proteins, carbohydrates,lipids, and nucleic acids in living cells.

    82. Write a balanced equation for the hydrolysis of lactose.

    83. Write a balanced equation for photosynthesis.

    84. Write and balance the equation for cellular respiration.

    85. Write a balanced equation for the synthesis of sucrosefrom glucose and fructose.

    Thinking Critically86. Using Numbers Approximately 38 moles of ATP are

    formed when glucose is completely oxidized during cel-lular respiration. If the heat of combustion for 1 mole ofglucose is 2.82 103 kJ/mol and each mole of ATPstores 30.5 kJ of energy, what is the efficiency of cellu-lar respiration in terms of the percentage of availableenergy that is stored in the chemical bonds of ATP?

    87. Recognizing Cause and Effect Some diets suggestseverely restricting the intake of lipids. Why is it not agood idea to eliminate all lipids from the diet?

    88. Making and Using Graphs A number of sat-urated fatty acids and values for some of theirphysical properties are listed in Table 24-2.

    a. Make a graph plotting number of carbon atomsversus melting point.

    b. Graph the number of carbon atoms versus density.c. Draw conclusions about the relationships between

    the number of carbon atoms in a saturated fattyacid and its density and melting point values.

    d. Predict the approximate melting point of a satu-rated fatty acid that has 24 carbon atoms.

    Writing in Chemistry89. Write a set of instructions that could be included in a

    package of contact-lens cleaning solution containingan enzyme. This enzyme catalyzes the breakdown ofprotein residues that adhere to the lenses. Includeinformation about the structure and function ofenzymes and the care that must be taken to avoid theirdenaturation during use.

    90. Use the library or the Internet to research cholesterol.Where is this molecule used in your body? What is itsfunction? Why is too much dietary cholesterol consid-ered to be bad for you?

    Cumulative ReviewRefresh your understanding of previous chapters byanswering the following.

    91. a. Write the balanced equation for the synthesis ofethanol from ethene and water.

    b. If 448 L of ethene gas reacts with excess water atSTP, how many grams of ethanol will be produced?(Chapter 14)

    92. Identify whether each of the reactants in these reac-tions is acting as an acid or a base. (Chapter 19) a. HBr H2O H3O

    Br

    b. NH3 HCOOH NH4 HCOO

    c. HCO3 H2O CO3

    H3O

    93. What is a voltaic cell? (Chapter 21)

    CHAPTER ASSESSMENT24

    Physical Properties of Saturated Fatty Acids

    Number Density of Melting (g/mL)

    carbon point (values at Name atoms (C) 6080C)

    Palmitic acid 16 63 0.853

    Myristic acid 14 58 0.862

    Arachidic acid 20 77 0.824

    Caprylic acid 8 16 0.910

    Docosanoicacid 22 80 0.822

    Stearic acid 18 70 0.847

    Lauric acid 12 44 0.868

    Table 24-2

  • Standardized Test Practice 803

    Use these questions and the test-taking tip to preparefor your standardized test.

    1. Which of the following is NOT true of carbohydrates?

    a. Monosaccharides in aqueous solutions interconvertcontinuously between an open-chain structure anda cyclic structure.

    b. The monosaccharides in starch are linked togetherby the same kind of bond that links the monosac-charides in lactose.

    c. All carbohydrates have the general chemical for-mula Cn(H2O)n.

    d. Cellulose, made only by plants, is easily digestibleby humans.

    2. All of the following are differences between RNA andDNA EXCEPT

    a. DNA contains the sugar deoxyribose, while RNAcontains the sugar ribose.

    b. RNA contains the nitrogen base uracil, while DNAdoes not.

    c. RNA is usually single-stranded, while DNA is usu-ally double-stranded.

    d. DNA contains the nitrogen base adenine, whileRNA does not.

    3. Cellular respiration produces about 38 moles of ATPfor every mole of glucose consumed:

    C6H12O6 6O2 6CO2 6H2O 38ATP

    If each molecule of ATP can release 30.5 kJ of energy,how much energy can be obtained from a candy barcontaining 130 g of glucose?

    a. 27.4 kJ c. 1159 kJb. 836 kJ d. 3970 kJ

    4. The sequence of bases in RNA determines thesequence of amino acids in a protein. Three bases codefor a single amino acid; for example, CAG is the codefor glutamine. Therefore, a strand of RNA 2.73 104

    bases long codes for a protein that has

    a. 8.19 104 amino acids.b. 9.10 103 amino acids.c. 2.73 104 amino acids.d. 4.55 103 amino acids.

    5. The equation for the alcoholic fermentation of glucoseis shown below:

    C6H12O6 2CH3CH2OH 2CO2 energy

    The ethanol content of wine is about 12%. Therefore,in every 100 g of wine there are 12.0 g of ethanol.How many grams of glucose were catabolized to pro-duce these 12.0 g of ethanol?

    a. 23.4 g c. 47.0 gb. 12.0 g d. 27.0 g

    Analyzing Tables Use the table below to answer thefollowing questions.Note: # of X # of molecules of X in one DNA molecule

    %X

    where X is any nitrogen base

    6. What is the %T of DNA D?

    a. 28.4% c. 71.6%b. 78.4% d. 21.6%

    7. Every nitrogen base found in a DNA molecule is partof a nucleotide of that molecule. The A nucleotide, Cnucleotide, G nucleotide, and T nucleotide have molarmasses of 347.22 g/mol, 323.20 g/mol, 363.23 g/mol,and 338.21 g/mol respectively. What is the mass ofone mole of DNA A?

    a. 2.79 105 g c. 2.6390 105 gb. 2.7001 105 g d. 2.72 105 g

    8. How many molecules of adenine are in one moleculeof DNA B?

    a. 402 c. 216b. 434 d. 175

    # of X# of A # of G # of C # of T

    STANDARDIZED TEST PRACTICECHAPTER 24

    Nitrogen Base Data for Four Different Double-Stranded DNA Molecules

    DNA Molecule # of A # of G # of C # of T %A %G %C %T

    A 165 ? 231 ? 20.8 ? 29.2 ?

    B ? 402 ? ? ? 32.5 ? ?

    C ? ? 194 234 ? ? 22.7 27.3

    D 266 203 ? ? 28.4 21.6 ? ?

    chemistrymc.com/standardized_test

    Use The Process of Elimination On anymultiple-choice test, there are two ways to find thecorrect answer to each question. Either you canchoose the right answer immediately or you caneliminate the answers that you know are wrong.

    http://chemistrymc.com/standardized_test

    Chemistry: Matter and ChangeContents in Brief Table of ContentsChapter 1: Introduction to ChemistrySection 1.1: The Stories of Two ChemicalsDiscovery Lab: Where is it?

    Section 1.2: Chemistry and MatterProblem-Solving Lab: Chemical ModelsCareers Using Chemistry: Chemistry Teacher

    Section 1.3: Scientific MethodsSection 1.4: Scientific ResearchBiology ConnectionMiniLab: Developing Observation SkillsChemLab: The Rubber Band StretchChemistry and Society: The Human Genome Project

    Chapter 1 Study GuideChapter 1 Assessment

    Chapter 2: Data AnalysisSection 2.1: Units of MeasurementDiscovery Lab: Layers of LiquidsAstronomy ConnectionMiniLab: Density of an Irregular Solid

    Section 2.2: Scientific Notation and Dimensional AnalysisSection 2.3: How reliable are measurements?Careers Using Chemistry: Scientific Illustrator

    Section 2.4: Representing DataProblem-Solving Lab: How does speed affect stopping distance?ChemLab: Using Density to Find the Thickness of a WireHow It Works: Ultrasound Devices

    Chapter 2 Study GuideChapter 2 Assessment

    Chapter 3: MatterProperties and Changes Section 3.1: Properties of MatterDiscovery Lab: Observing Chemical ChangeCareers Using Chemistry: Science WriterProblem-Solving Lab: How is compressed gas released?

    Section 3.2: Changes in MatterSection 3.3: Mixtures of MatterMiniLab: Separating Ink Dyes

    Section 3.4: Elements and CompoundsHistory ConnectionChemLab: Matter and Chemical ReactionsChemistry and Society: Green Buildings

    Chapter 3 Study GuideChapter 3 Assessment

    Chapter 4: The Structure of the AtomSection 4.1: Early Theories of MatterDiscovery Lab: Observing Electrical ChargeHistory Connection

    Section 4.2: Subatomic Particles and the Nuclear AtomProblem-Solving Lab: Interpreting STM Images

    Section 4.3: How Atoms DifferMiniLab: Modeling Isotopes

    Section 4.4: Unstable Nuclei and Radioactive DecayCareers Using Chemistry: Radiation Protection TechnicianChemLab: Very Small ParticlesChemistry and Society: Nanotechnology

    Chapter 4 Study GuideChapter 4 Assessment

    Chapter 5: Electrons in AtomsSection 5.1: Light and Quantized EnergyDiscovery Lab: What's Inside?MiniLab: Flame Tests

    Section 5.2: Quantum Theory and the AtomProblem-Solving Lab: How was Bohr's atomic model able to explain the line spectrum of hydrogen?Physics Connection

    Section 5.3: Electron ConfigurationsCareers Using Chemistry: SpectroscopistChemLab: Line SpectraHow It Works: Lasers

    Chapter 5 Study GuideChapter 5 Assessment

    Chapter 6: The Periodic Table and Periodic LawSection 6.1: Development of the Modern Periodic TableDiscovery Lab: Versatile MetalsAstronomy ConnectionProblem-Solving Lab: Franciumsolid, liquid, or gas?

    Section 6.2: Classification of the ElementsCareers Using Chemistry: Medical Lab Technician

    Section 6.3: Periodic TrendsMiniLab: Periodicity of Molar Heats of Fusion and VaporizationChemLab: Descriptive Chemistry of the ElementsHow It Works: Television Screen

    Chapter 6 Study GuideChapter 6 Assessment

    Chapter 7: The ElementsSection 7.1: Properties of s-Block ElementsDiscovery Lab: Magnetic MaterialsCareers Using Chemistry: DietitianMiniLab: Properties of Magnesium

    Section 7.2: Properties of p-Block ElementsHistory ConnectionProblem-Solving Lab: Cost of Fertilizer

    Section 7.3: Properties of d-Block and f-Block ElementsChemLab: Hard WaterHow It Works: Semiconductor Chips

    Chapter 7 Study GuideChapter 7 Assessment

    Chapter 8: Ionic CompoundsSection 8.1: Forming Chemical BondsDiscovery Lab: An Unusual Alloy

    Section 8.2: The Formation and Nature of Ionic BondsProblem-Solving Lab: How is color related to a transferred electron?

    Section 8.3: Names and Formulas for Ionic CompoundsCareers Using Chemistry: Wastewater Treatment OperatorEarth Science Connection

    Section 8.4: Metallic Bonds and Properties of MetalsMiniLab: Heat Treatment of SteelChemLab: Making Ionic CompoundsEveryday Chemistry: Color of Gems

    Chapter 8 Study GuideChapter 8 Assessment

    Chapter 9: Covalent BondingSection 9.1: The Covalent BondDiscovery Lab: Oil and Vinegar Dressing

    Section 9.2: Naming MoleculesCareers Using Chemistry: Organic Chemist

    Section 9.3: Molecular StructuresSection 9.4: Molecular ShapeMiniLab: Building VSEPR Models

    Section 9.5: Electronegativity and PolarityHistory ConnectionProblem-Solving Lab: How do dispersion forces determine the boiling point of a substance?ChemLab: ChromatographyHow It Works: Microwave Oven

    Chapter 9 Study GuideChapter 9 Assessment

    Chapter 10: Chemical ReactionsSection 10.1: Reactions and EquationsDiscovery Lab: Observing a ChangeEarth Science Connection

    Section 10.2: Classifying Chemical ReactionsProblem-Solving Lab: Can you predict the reactivities of halogens?

    Section 10.3: Reactions in Aqueous SolutionsMiniLab: Observing a Precipitate-Forming ReactionCareers Using Chemistry: Pastry ChefChemLab Small Scale: Activities of MetalsHow It Works: Hot and Cold Packs

    Chapter 10 Study GuideChapter 10 Assessment

    Chapter 11: The MoleSection 11.1: Measuring MatterDiscovery Lab: How much is a mole?History Connection

    Section 11.2: Mass and the MoleProblem-Solving Lab: Molar Mass, Avogadro's Number and the Atomic Nucleus

    Section 11.3: Moles of CompoundsSection 11.4: Empirical and Molecular FormulasCareers Using Chemistry: Analytical ChemistMiniLab: Percent Composition and Gum

    Section 11.5: The Formula for a HydrateChemLab: Hydrated CrystalsChemistry and Technology: Making Medicines

    Chapter 11 Study GuideChapter 11 Assessment

    Chapter 12: StoichiometrySection 12.1: What is stoichiometry?Discovery Lab: Observing a Chemical ReactionCareers Using Chemistry: Pharmacist

    Section 12.2: Stoichiometric CalculationsMiniLab: Baking Soda Stoichiometry

    Section 12.3: Limiting ReactantsBiology Connection

    Section 12.4: Percent YieldProblem-Solving Lab: How does the surface area of a solid reactant affect percent yield?ChemLab: A Mole RatioHow It Works: Air Bags

    Chapter 12 Study GuideChapter 12 Assessment

    Chapter 13: States of MatterSection 13.1: GasesDiscovery Lab: Defying DensityProblem-Solving Lab: How are the depth of a dive and pressure related?

    Section 13.2: Forces of AttractionSection 13.3: Liquids and SolidsMiniLab: Crystal Unit Cell ModelsCareers Using Chemistry: Materials Engineer

    Section 13.4: Phase ChangesEarth Science ConnectionChemLab Small Scale: Comparing Rates of EvaporationEveryday Chemistry: Metals With a Memory

    Chapter 13 Study GuideChapter 13 Assessment

    Chapter 14: GasesSection 14.1: The Gas LawsDiscovery Lab: More Than Just Hot AirCareers Using Chemistry: MeteorologistHistory ConnectionProblem-Solving Lab: How is turbocharging in a car engine maximized?

    Section 14.2: The Combined Gas Law and Avogadro's PrincipleSection 14.3: The Ideal Gas LawMiniLab: The Density of Carbon Dioxide

    Section 14.4: Gas StoichiometryChemLab: Using the Ideal Gas LawChemistry and Technology: Giving a Lift to Cargo

    Chapter 14 Study GuideChapter 14 Assessment

    Chapter 15: SolutionsSection 15.1: What are solutions?Discovery Lab: Solution FormationEarth Science Connection

    Section 15.2: Solution ConcentrationSection 15.3: Colligative Properties of SolutionsMiniLab: Freezing Point DepressionCareers Using Chemistry: Renal Dialysis Technician

    Section 15.4: Heterogeneous MixturesProblem-Solving Lab: How can you measure the turbidity of a colloid?ChemLab: Beer's LawChemistry and Society: Sickle-Cell Disease

    Chapter 15 Study GuideChapter 15 Assessment

    Chapter 16: Energy and Chemical ChangeSection 16.1: EnergyDiscovery Lab: Temperature of a Reaction

    Section 16.2: Heat in Chemical Reactions and ProcessesCareers Using Chemistry: Heating and Cooling Specialist

    Section 16.3: Thermochemical EquationsProblem-Solving Lab: How much energy is needed to heat water from a solid to a vapor?MiniLab: Enthalpy of Fusion for Ice

    Section 16.4: Calculating Enthalpy ChangeSection 16.5: Reaction SpontaneityEarth Science ConnectionChemLab: CalorimetryHow It Works: Refrigerator

    Chapter 16 Study GuideChapter 16 Assessment

    Chapter 17: Reaction RatesSection 17.1: A Model for Reaction RatesDiscovery Lab: Speeding ReactionsProblem-Solving Lab: Speed and Energy of Collision

    Section 17.2: Factors Affecting Reaction RatesMiniLab: Examining Reaction Rate and Temperature

    Section 17.3: Reaction Rate LawsPhysics Connection

    Section 17.4: Instantaneous Reaction Rates and Reaction MechanismsCareers Using Chemistry: Food TechnologistChemLab: Concentration and Reaction RateHow It Works: Catalytic Converter

    Chapter 17 Study GuideChapter 17 Assessment

    Chapter 18: Chemical EquilibriumSection 18.1: Equilibrium: A State of Dynamic BalanceDiscovery Lab: What's equal about equilibrium?Physics Connection

    Section 18.2: Factors Affecting Chemical EquilibriumCareers Using Chemistry: Nurse AnesthetistMiniLab: Shifts in Equilibrium

    Section 18.3: Using Equilibrium ConstantsProblem-Solving Lab: How does fluoride prevent tooth decay?ChemLab Small Scale: Comparing Two Solubility Product ConstantsChemistry and Technology: The Haber Process

    Chapter 18 Study GuideChapter 18 Assessment

    Chapter 19: Acids and BasesSection 19.1: Acids and Bases: An IntroductionDiscovery Lab: Investigating What's in Your CupboardsCareers Using Chemistry: Agricultural TechnicianEarth Science Connection

    Section 19.2: Strengths of Acids and BasesMiniLab: Acid Strength

    Section 19.3: What is pH?Section 19.4: NeutralizationProblem-Solving Lab: How does your blood maintain its pH?ChemLab: Standardizing a Base Solution by TitrationHow It Works: Antacids

    Chapter 19 Study GuideChapter 19 Assessment

    Chapter 20: Redox ReactionsSection 20.1: Oxidation and ReductionDiscovery Lab: Observing an Oxidation-Reduction ReactionBiology ConnectionMiniLab: Cleaning by RedoxCareers Using Chemistry: Photochemical Etching Artist

    Section 20.2: Balancing Redox EquationsProblem-Solving Lab: How does redox lift a space shuttle?

    Section 20.3: Half-ReactionsChemLab: Redox ReactionsHow It Works: Photographic Film

    Chapter 20 Study GuideChapter 20 Assessment

    Chapter 21: ElectrochemistrySection 21.1: Voltaic CellsDiscovery Lab: A Lemon Battery?

    Section 21.2: Types of BatteriesCareers Using Chemistry: ElectrochemistProblem-Solving Lab: Interpreting Scientific IllustrationsMiniLab: Corrosion

    Section 21.3: ElectrolysisHistory ConnectionChemLab CBL: Voltaic Cell PotentialsChemistry and Technology: Fuel Cells

    Chapter 21 Study GuideChapter 21 Assessment

    Chapter 22: HydrocarbonsSection 22.1: AlkanesDiscovery Lab: Viscosity of Motor OilBiology ConnectionCareers Using Chemistry: Alternative Fuel Technician

    Section 22.2: Cyclic Alkanes and Alkane PropertiesSection 22.3: Alkenes and AlkynesMiniLab: Synthesis and Reactivity of Ethyne

    Section 22.4: IsomersProblem-Solving Lab: Identifying Structural, Geometric, and Optical Isomers

    Section 22.5: Aromatic Hydrocarbons and PetroleumEarth Science ConnectionChemLab: Analyzing Hydrocarbon Burner GasesEveryday Chemistry: Unlimited Alternative Energy

    Chapter 22 Study GuideChapter 22 Assessment

    Chapter 23: Substituted Hydrocarbons and Their ReactionsSection 23.1: Functional GroupsDiscovery Lab: Making SlimeAstronomy Connection

    Section 23.2: Alcohols, Ethers, and AminesSection 23.3: Carbonyl CompoundsMiniLab: Making an Ester

    Section 23.4: Other Reactions of Organic CompoundsProblem-Solving Lab: Categorizing Organic Compounds

    Section 23.5: PolymersCareers Using Chemistry: Dental AssistantChemLab: Properties of AlcoholsChemistry and Technology: Carbon: Stronger Than Steel?

    Chapter 23 Study GuideChapter 23 Assessment

    Chapter 24: The Chemistry of LifeSection 24.1: ProteinsDiscovery Lab: Testing for Simple Sugars

    Section 24.2: CarbohydratesSection 24.3: LipidsBiology ConnectionMiniLab: A Saponification Reaction

    Section 24.4: Nucleic AcidsProblem-Solving Lab: How does DNA replicate?

    Section 24.5: MetabolismCareers Using Chemistry: Personal TrainerChemLab CBL: Alcoholic Fermentation in YeastEveryday Chemistry: Sense of Smell

    Chapter 24 Study GuideChapter 24 Assessment

    Chapter 25: Nuclear ChemistrySection 25.1: Nuclear RadiationDiscovery Lab: Chain ReactionsPhysics Connection

    Section 25.2: Radioactive DecaySection 25.3: TransmutationMiniLab: Modeling Radioactive Decay

    Section 25.4: Fission and Fusion of Atomic NucleiSection 25.5: Applications and Effects of Nuclear ReactionsCareers Using Chemistry: Radiation TherapistProblem-Solving Lab: How does distance affect radiation exposure?ChemLab CBL: Measuring Naturally Occurring RadiationChemistry and Society: The Realities of Radon

    Chapter 25 Study GuideChapter 25 Assessment

    Chapter 26: Chemistry in the EnvironmentSection 26.1: Earth's AtmosphereDiscovery Lab: Clarification of WaterCareers Using Chemistry: Environmental Health InspectorEarth Science ConnectionMiniLab: Acid Rain in a Bag

    Section 26.2: Earth's WaterBiology Connection

    Section 26.3: Earth's CrustSection 26.4: Cycles in the EnvironmentProblem-Solving Lab: Global warming: fact or fiction?ChemLab CBL: Solar PondHow It Works: Water Softener

    Chapter 26 Study GuideChapter 26 Assessment

    AppendicesAppendix A: Supplemental Practice ProblemsAppendix B: Math HandbookAppendix C: TablesAppendix D: Solutions to Practice ProblemsAppendix E: Try At Home Labs

    GlossaryIndexPhoto Credits

    FeaturesChemLabMiniLabProblem-Solving LabDiscovery LabHow It WorksEveryday ChemistryChemistry and SocietyChemistry and TechnologyCareers Using ChemistryConnectionsEarth ScienceBiologyHistoryAstronomyPhysics

    Student WorksheetsCBL Laboratory ManualTo the StudentOrganization of ActivitiesSending Data to Graphical AnalysisCBL EquipmentSafety in the LaboratorySafety SymbolsLaboratory ActivitiesLab 1: Quantitative and Qualitative ObservationsLab 2: ConductivityLab 3: Melting and Freezing PointsLab 4: Boyles LawLab 5: Gay-Lussacs LawLab 6: Determining Molar Mass Using Freezing Point DepressionLab 7: CalorimetryLab 8: Hesss LawLab 9: Determine the Molar Mass of an Unknown AcidLab 10: Reaction Potentials of Metals

    Challenge ProblemsChapter 1: Production of Chlorofluorocarbons, 19501992Chapter 2: Population Trends in the United StatesChapter 3: Physical and Chemical ChangesChapter 4: Isotopes of an ElementChapter 5: Quantum NumbersChapter 6: Dbereiners TriadsChapter 7: Abundance of the ElementsChapter 8: Comparing the Structures of Atoms and IonsChapter 9: Exceptions to the Octet RuleChapter 10: Balancing Chemical EquationsChapter 11: Using Mole-Based ConversionsChapter 12: Mole Relationships in Chemical ReactionsChapter 13: Intermolecular Forces and Boiling PointsChapter 14: A Simple Mercury BarometerChapter 15: Vapor Pressure LoweringChapter 16: Standard Heat of FormationChapter 17: Determining Reaction RatesChapter 18: Changing Equilibrium Concentrations in a ReactionChapter 19: Swimming Pool ChemistryChapter 20: Balancing OxidationReduction EquationsChapter 21: Effect of Concentration on Cell PotentialChapter 22: Structural Isomers of HexaneChapter 23: Boiling Points of Organic FamiliesChapter 24: The Chemistry of LifeChapter 25: The Production of Plutonium-239Chapter 26: The Phosphorus Cycle

    ChemLab and MiniLab WorksheetsChapter 1Chapter 2Chapter 3Chapter 4Chapter 5Chapter 6Chapter 7Chapter 8Chapter 9Chapter 10Chapter 11Chapter 12Chapter 13Chapter 14Chapter 15Chapter 16Chapter 17Chapter 18Chapter 19Chapter 20Chapter 21Chapter 22Chapter 23Chapter 24Chapter 25Chapter 26

    Forensics Laboratory ManualIntroduction to Forensic Science: To the StudentForensic Skills: Observing the Scene and Collecting DataForensic Skills: FingerprintsForensic Skills: Blood IdentificationThe Truth TableSafety in the LaboratorySafety SymbolsCrime A: The Counterfeit Coin CaperLab A1: What metal can it be?Lab A2: Separation of a MixtureLab A3: Analyzing and Identifying White Solids

    Crime B: The Case of the Problem PatentLab B1: Using Paper Chromatography to Separate a MixtureLab B2: ConductivityLab B3: pHLab B4: Effects of Acids and Bases on the Color of a Dye

    Crime C: The Case of the Fallen WalkwayLab C1: Oxidation and ReductionLab C2: Sources and Causes of CorrosionLab C3: Identifying Sacrificial Metals

    Laboratory ManualHow to Use This Laboratory ManualWriting a Laboratory ReportLaboratory EquipmentSafety in the LaboratorySafety SymbolsLaboratory ActivitiesChapter 1: Introduction to Chemistry1.1: Laboratory Techniques and Lab Safety1.2: Effective Use of a Bunsen Burner

    Chapter 2: Data Analysis2.1: Density2.2: Making a Graph

    Chapter 3: MatterProperties and Changes3.1: The Density of Wood3.2: Properties of Water

    Chapter 4: The Structure of the Atom4.1: Simulation of Rutherfords Gold Foil Experiment4.2: Half-life of Barium-137m

    Chapter 5: Electrons in Atoms5.1: The Photoelectric Effect5.2: Electron Charge to Mass Ratio

    Chapter 6: The Periodic Table and Periodic Law6.1: Properties of the Periodic Table6.2: Periodic Trends in the Periodic Table

    Chapter 7: The Elements7.1: Is there potassium in coffee?7.2: The Periodic Puzzle

    Chapter 8: Ionic Compounds8.1: Properties of Ionic Compounds8.2: Formation of a Salt

    Chapter 9: Covalent Bonding9.1: Covalent Bonding in Medicines9.2: Covalent Compounds

    Chapter 10: Chemical Reactions10.1: Single-Replacement Reactions10.2: Double-Replacement Reactions

    Chapter 11: The Mole11.1: Estimating the Size of a Mole11.2: Mole Ratios

    Chapter 12: Stoichiometry12.1: Observing a Limiting Reactant12.2: Determining Reaction Ratios

    Chapter 13: States of Matter13.1: Freezing Bacteria13.2: Boiling Points

    Chapter 14: Gases14.1: Charless Law14.2: Boyles Law

    Chapter 15: Solutions15.1: Making a Solubility Curve15.2: Freezing Point Depression

    Chapter 16: Energy and Chemical Change16.1: Heats of Solution and Reaction16.2: Heat of Combustion of Candle Wax

    Chapter 17: Reaction Rates17.1: The Rate of a Reaction17.2: Surface Area and Reaction Rate

    Chapter 18: Chemical Equilibrium18.1: Reversible Reactions18.2: Equilibrium

    Chapter 19: Acids and Bases19.1: Acids, Bases, and Neutralization19.2: Determining the Percent of Acetic Acid in Vinegar

    Chapter 20: Redox Reactions20.1: Electron-Losing Tendencies of Metals20.2: Determining Oxidation Numbers

    Chapter 21: Electrochemistry21.1: Electrolysis of Water21.2: Electroplating

    Chapter 22: Hydrocarbons22.1: Isomerism22.2: The Ripening of Fruit with Ethene

    Chapter 23: Substituted Hydrocarbons and Their Reactions23.1: The Characterization of Carbohydrates23.2: Polymerization Reactions

    Chapter 24: The Chemistry of Life24.1: Denaturation24.2: Saturated and Unsaturated Fats

    Chapter 25: Nuclear Chemistry25.1: Radioisotope Dating25.2: Modeling Isotopes

    Chapter 26: Chemistry in the Environment26.1: Organisms That Break Down Oil26.2: Growth of Algae as a Function of Nitrogen Concentration

    Reviewing ChemistryStudent IntroductionChapter Review QuestionsChapter 1: Introduction to ChemistryChapter 2: Data AnalysisChapter 3: MatterProperties and ChangesChapter 4: The Structure of the AtomChapter 5: Electrons in AtomsChapter 6: The Periodic Table and Periodic LawChapter 7: The ElementsChapter 8: Ionic CompoundsChapter 9: Covalent BondingChapter 10: Chemical ReactionsChapter 11: The MoleChapter 12: StoichiometryChapter 13: States of MatterChapter 14: GasesChapter 15: SolutionsChapter 16: Energy and Chemical ChangeChapter 17: Reaction RatesChapter 18: Chemical EquilibriumChapter 19: Acids and BasesChapter 20: Redox ReactionsChapter 21: ElectrochemistryChapter 22: HydrocarbonsChapter 23: Substituted Hydrocarbons and Their ReactionsChapter 24: The Chemistry of LifeChapter 25: Nuclear ChemistryChapter 26: Chemistry in the Environment

    Small-Scale Laboratory ManualTo the StudentSmall-Scale Laboratory TechniquesSafety in the LaboratorySafety SymbolsLaboratory ActivitiesLab 1: Small-Scale Laboratory TechniquesLab 2: Comparing the Density of MetalsLab 3: Separation of AspirinLab 4: Periodicity and the Properties of ElementsLab 5: Properties of Transition MetalsLab 6: Modeling Molecular ShapesLab 7: Solutions and PrecipitatesLab 8: Determining Avogadros NumberLab 9: Measuring Boiling PointLab 10: Relating Gas Pressure and Gas VolumeLab 11: Effect of Temperature on SolubilityLab 12: Specific Heat of MetalsLab 13: Energy Changes in Chemical and Physical ProcessesLab 14: Determining Reaction OrdersLab 15: Observing EquilibriumLab 16: Exploring Chemical EquilibriumLab 17: Comparing the Strengths of AcidsLab 18: Testing the Acidity of AspirinLab 19: Reduction of ManganeseLab 20: Plants Produce Oxygen

    Solving Problems: A Chemistry HandbookChapter 1: Introduction to Chemistry1.1: The Stories of Two Chemicals1.2: Chemistry and Matter1.3: Scientific Methods1.4: Scientific Research

    Chapter 2: Data Analysis2.1: Units of Measurement2.2: Scientific Notation and Dimensional Analysis2.3: How reliable are measurements?2.4: Representing Data

    Chapter 3: MatterProperties and Changes3.1: Properties of Matter3.2: Changes in Matter3.3: Mixtures of Matter3.4: Elements and Compounds

    Chapter 4: The Structure of the Atom4.1: Early Theories of Matter4.2: Subatomic Particles and the Nuclear Atom4.3: How Atoms Differ4.4: Unstable Nuclei and Radioactive Decay

    Chapter 5: Electrons in Atoms5.1: Light and Quantized Energy5.2: Quantum Theory and the Atom5.3: Electron Configurations

    Chapter 6: The Periodic Table and Periodic Law6.1: Development of the Modern Periodic Table6.2: Classification of the Elements6.3: Periodic Trends

    Chapter 7: The Elements7.1: Properties of s-Block Elements7.2: Properties of p-Block Elements7.3: Properties of d-Block and f-Block Elements

    Chapter 8: Ionic Compounds8.1: Forming Chemical Bonds8.2: The Formation and Nature of Ionic Bonds8.3: Names and Formulas for Ionic Compounds8.4: Metallic Bonds and Properties of Metals

    Chapter 9: Covalent Bonding9.1: The Covalent Bond9.2: Naming Molecules9.3: Molecular Structures9.4: Molecular Shape9.5: Electronegativity and Polarity

    Chapter 10: Chemical Reactions10.1: Reactions and Equations10.2: Classifying Chemical Reactions10.3: Reactions in Aqueous Solutions

    Chapter 11: The Mole11.1: Measuring Matter11.2: Mass and the Mole11.3: Moles of Compounds11.4: Empirical and Molecular Formulas11.5: The Formula for a Hydrate

    Chapter 12: Stoichiometry12.1: What is stoichiometry?12.2: Stoichiometric Calculations12.3: Limiting Reactants12.4: Percent Yield

    Chapter 13: States of Matter13.1: Gases13.2: Forces of Attraction13.3: Liquids and Solids13.4: Phase Changes

    Chapter 14: Gases14.1: The Gas Laws14.2: The Combined Gas Law and Avogadros Principle14.3: The Ideal Gas Law14.4: Gas Stoichiometry

    Chapter 15: Solutions15.1: What are solutions?15.2: Solution Concentration15.3: Colligative Properties of Solutions15.4: Heterogeneous Mixtures

    Chapter 16: Energy and Chemical Change16.1: Energy16.2: Heat in Chemical Reactions and Processes16.3: Thermochemical Equations16.4: Calculating Enthalpy Change16.5: Reaction Spontaneity

    Chapter 17: Reaction Rates17.1: A Model for Reaction Rates17.2: Factors Affecting Reaction Rates17.3: Reaction Rate Laws17.4: Instantaneous Reaction Rates and Reaction Mechanisms

    Chapter 18: Chemical Equilibrium18.1: Equilibrium: A State of Dynamic Balance18.2: Factors Affecting Chemical Equilibrium18.3: Using Equilibrium Constants

    Chapter 19: Acids and Bases19.1: Acids and Bases: An Introduction19.2: Strengths of Acids and Bases19.3: What is pH?19.4: Neutralization

    Chapter 20: Redox Reactions20.1: Oxidation and Reduction20.2: Balancing Redox Equations20.3: Half-Reactions

    Chapter 21: Electrochemistry21.1: Voltaic Cells21.2: Types of Batteries21.3: Electrolysis

    Chapter 22: Hydrocarbons22.1: Alkanes22.2: Cyclic Alkanes and Alkane Properties22.3: Alkenes and Alkynes22.4: Isomers22.5: Aromatic Hydrocarbons and Petroleum

    Chapter 23: Substituted Hydrocarbons and Their Reactions23.1: Functional Groups23.2: Alcohols, Ethers, and Amines23.3: Carbonyl Compounds23.4: Other Reactions of Organic Compounds23.5: Polymers

    Chapter 24: The Chemistry of Life24.1: Proteins24.2: Carbohydrates24.3: Lipids24.4: Nucleic Acids24.5: Metabolism

    Chapter 25: Nuclear Chemistry25.1: Nuclear Radiation25.2: Radioactive Decay25.3: Transmutation25.4: Fission and Fusion of Atomic Nuclei25.5: Applications and Effects of Nuclear Reactions

    Chapter 26: Chemistry in the Environment26.1: Earths Atmosphere26.2: Earths Water26.3: Earths Crust26.4: Cycles in the Environment

    Spanish ResourcesCaptula 1: Introduccin a la qumicaCaptula 2: Anlisis de datosCaptula 3: Cambios y propiedades de la materiaCaptula 4: La estructura del tomoCaptula 5: Los electrones del tomoCaptula 6: La tabla peridica y la ley peridicaCaptula 7: Los elementosCaptula 8: Compuestos inicosCaptula 9: Enlaces covalentesCaptula 10: Reacciones qumicasCaptula 11: El molCaptula 12: EstequiometraCaptula 13: Estados de la materiaCaptula 14: GasesCaptula 15: SolucionesCaptula 16: Cambios de energa y cambios qumicosCaptula 17: Tasas de reaccinCaptula 18: Equilibrio qumicoCaptula 19: cidos y basesCaptula 20: Reacciones redoxCaptula 21: ElectroqumicaCaptula 22: HidrocarburosCaptula 23: Los hidrocarburos de sustitucin y sus reaccionesCaptula 24: La qumica de la vidaCaptula 25: Qumica nuclearCaptula 26: Qumica en el ambienteGlossary/Glosario

    Study Guide for Content MasteryTo the StudentStudy SkillsChapter 1: Introduction to ChemistryChapter 2: Data AnalysisChapter 3: MatterProperties and ChangesChapter 4: The Structure of the AtomChapter 5: Electrons in AtomsChapter 6: The Periodic Table and Periodic LawChapter 7: The ElementsChapter 8: Ionic CompoundsChapter 9: Covalent BondingChapter 10: Chemical ReactionsChapter 11: The MoleChapter 12: StoichiometryChapter 13: States of MatterChapter 14: GasesChapter 15: SolutionsChapter 16: Energy and Chemical ChangeChapter 17: Reaction RatesChapter 18: Chemical EquilibriumChapter 19: Acids and BasesChapter 20: Redox ReactionsChapter 21: ElectrochemistryChapter 22: HydrocarbonsChapter 23: Substituted Hydrocarbons and Their ReactionsChapter 24: The Chemistry of LifeChapter 25: Nuclear ChemistryChapter 26: Chemistry in the Environment

    Supplemental ProblemsChapter 2: Data AnalysisChapter 3: MatterProperties and ChangesChapter 4: The Structure of the AtomChapter 5: Electrons in AtomsChapter 6: The Periodic Table and Periodic LawChapter 10: Chemical ReactionsChapter 11: The MoleChapter 12: StoichiometryChapter 13: States of MatterChapter 14: GasesChapter 15: SolutionsChapter 16: Energy and Chemical ChangeChapter 17: Reaction RatesChapter 18: Chemical EquilibriumChapter 19: Acids and BasesChapter 20: Redox ReactionsChapter 21: ElectrochemistryChapter 22: HydrocarbonsChapter 24: The Chemistry of LifeChapter 25: Nuclear Chemistry

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