Chapter 3Macromolecules

Objectives

• Distinguish between organic and inorganic compounds.

• Explain the importance of carbon bonding in biological molecules.

• Identify functional groups in biological molecules.

• Summarize how large carbon molecules are synthesized and broken

down.

• Describe how the breaking down of ATP supplies energy to drive chemical

reactions.

Section 1 Carbon Compounds

Carbon Bonding• Organic compounds contain CARBON (C) and are found in living things.• Most inorganic compounds DO NOT contain carbon atoms.

– Some that do: carbon dioxide (CO2), cyanide (HCN)

Which of the following do you think are organic? Which are inorganic?

H2ONa-Cl

Carbon Bonding• Carbon atoms readily form four covalent bonds with other atoms

(including carbon!) because it contains only four electrons in its outer energy level.

• These bonds allow carbon atoms to form a wide variety of simple and complex organic compounds with single, double, and triple bonds.

Carbon Bonding

Functional Groups• Functional groups are groups of atoms that influence the properties of

molecules and the chemical reactions they’re involved in.

– Hydroxyl : rubbing alcohol• Makes molecule polar• Polar molecules are hydrophillic (soluble in water)

– Carboxyl : formic acid

– Amine : glycine

– Phosphate : nucleic acid

Matching

A. PhosphateB. CarboxylC. HydroxylD. Amine

Large Carbon Molecules• Condensation reactions join

– Monomers (small simple molecules) into– Polymers (chains of molecules)

• aka “macromolecules”• EX: carbs, lipids, proteins, and nucleic acids

– A condensation reaction releases water as a by-product– In a hydrolysis reaction, water is used to split polymers into

monomers

Condensation

Hydrolysis

+ H2O

Energy Currency• Adenosine triphosphate (ATP) stores and releases energy during cell

processes, enabling organisms to function.

Objectives• Distinguish between monosaccharides, disaccharides, and

polysaccharides

• Explain the relationship between amino acids and protein structure.

• Describe the induced fit model of enzyme action.

• Compare the structure and function of each of the different types of

lipids.

• Compare the nucleic acids DNA and RNA.

Section 2 Molecules of Life

Macromolecules• Four main classes essential to life:

1. Carbohydrates2. Proteins3. Lipids 4. Nucleic Acids

1. Carbohydrates• Carbohydrates are organic compounds composed of C, H, and O in about

a 1:2:1 ratio

• Source of energy for organisms

• Structural materials in organisms

• Hydrophilic

1. Carbohydrates• Carbohydrates are made up of monomers called monosaccharides (“one

sugar”)• EX: glucose, fructose, sucrose

1. Carbohydrates• Two monosaccharides join to form a double sugar called a disaccharide

(“two sugars”)– EX: fructose + glucose = sucrose

• A polysaccharide (“many sugars”) is made of three or more monosaccharides– EX: glycogen, starch, cellulose

2. Proteins• Enzymes…• Are essential for the functioning of any cell.• Many of them are proteins• speed up chemical reactions and bind to specific substrates. Enzyme

reactions depend on the physical fit between the enzyme’s active site and the substrate (the reactant being catalyzed)

2. Proteins• Proteins are organic compounds composed mainly of C, H, O, and N

• Hydrophilic

• Forms of proteins:– Enzymes– Most anti-bodies– Pigments– Hemoglobin– Hormones

2. Proteins• Proteins are long chains of monomers called amino acids.

• The sequence of amino acids determines a protein’s shape and function.

• There are 20 common in plants and animals

• Two amino acids are joined by peptide bonds (covalent) to form a dipeptide (“two amino acids”)

• A long chain of amino acids is called a polypeptide (“many amino acids”).

2. Proteins• Protein Structure

2. Proteins

2. Proteins• Without enzymes, chemical reactions in the body would be too slow to

support life• Enzymes are used over and over• If the environment changes, the enzyme might not work properly because

the active site may change shape!

3. Lipids• Lipids are large nonpolar molecules (don’t dissolve in water)

• Store the most energy (they have more C and H atoms)

• Important part of cell membranesTypes of Lipids

• Triglycerides• Phospholipids• Steroids• Waxes• Pigments

3. Lipids• Fatty Acids

– The most abundant lipids contain fatty acids, unbranched carbon molecules with a hydrophilic end and a hydrophobic end.

• When none of the carbon atoms have double bonds, it is called saturated

• When any of the carbon atoms are double bonded, it is called unsaturated

3. Lipids• Triglycerides

– Triglycerides consist of 3 fatty acids and 1 molecules of glycerol.

– Saturated triglycerides have saturated fatty acids, giving them high melting points so they are solid at room temp.

Can you think of any examples?

3. Lipids• Triglycerides

– Unsaturated triglycerides have unsaturated fatty acids, so they are soft or liquid at room temp.

– Usually found in plant seeds

Can you think of any examples?

3. More Lipids• Phospholipids consist of 2 fatty acids, 1 glycerol, and a phosphate group.

– Make up the lipid bilayer of cell membranes

3. Even More Lipids• Waxes

– A wax is made up of one long fatty acid chain joined to one long alcohol

– Waterproof

• Steroids– A steroid is composed of four fused carbon

rings.– Hormones– Cholesterol

Does anyone know any steroids?

4. Nucleic Acids• A nucleic acid is a large, complex organic molecule that stores and

transports information.– Made of N, C, H, O, P– Double helix structure– 2 types:

• Ribonucleic Acid (RNA)• Deoxyribonucleic Acid (DNA)

4. Nucleic Acids• DNA

– DNA is a nucleic acid made of thousand of nucleotides (the monomers)– Contains the genetic information for cells– Humans have 46 molecules of DNA (or 46 chromosomes)– What makes up DNA?

• Sugar (deoxyribose)• Phosphate group• Base (adenine, thymine, cytosine, guanine)

4. Nucleic Acids

DNA Animation Video!

4. Nucleic Acids• RNA

– RNA stores and transfers info from DNA to construct proteins– Can act as an enzyme