The Chemistry of Life

An atom is the basic unit of matter

The three subatomic particles are:1. Neutrons – no charge2. Protons – + charge3. Electrons – - charge

The nucleus is the center of an atom and is made up of protons + neutrons

Electrons are located outside of the nucleus in the electron cloud. Electrons are in constant motion.

Atoms

An element is a pure substance that consists entirely of one type of atom Isotopes are atoms of the same element that differ

in the number of neutronsEx. carbon-12, carbon-13, carbon-14

Mass Number = Protons + NeutronsAtomic Number = Protons

Pure Substance

A compound is a substance that is formed from 2 or more elements.Chemical & Physical properties of compounds

are usually different from the elements that make them up. Ex. 2H2(g) + O2(g) 2H2O(l)

Chemical Bond – is the energy that holds atoms in a compound together. They are formed from electrons.

Pure Substances

2 main types of chemical bondsIonic Bonds – electrons are

gained or lost by each atom

2Na + Cl2 2NaCl

Covalent Bonds – electrons are sharing between atoms

C + O2 CO2

Pure Substances

A polar molecule is a molecule that has an uneven distribution of charges due to the hydrogen bonding between hydrogen and oxygen.

Because water molecules have slightly + and – ends they can attract each other as well as other polar substances

Water

A mixture is a material composed of 2 or more compounds or elements that are physically (Not Chemically) combined together.

Types of Mixtures:Homogeneous – even distribution of

components.Ex. Solution – shampoo, powdered drinks,

lotion, etc2 parts of a solution:

1. Solute – the substance that is dissolved2. Solvent – the substance doing the

dissolving Heterogeneous – components are easily

distinguishable, and easily separatedEx. Oil + water, salads, pizza

Mixtures

Suspension – materials that do not dissolve when placed in water but break up into smaller pieces and do not settle out.Ex. Italian dressing, dust particles in air, muddy

water, etc.

Mixtures

pH scale – indicates the concentration of H+ ions in a solutionRange is from 0 – 14

0 – 6 Acids7 Neutral usually water8 – 14 Bases

Acids – form hydrogen ions [H+] in a solutionBases – form hydroxide ions [-OH] in a

solution

Acids, Bases, and pH

Buffers are weak acids or bases that are added to help neutralizing a solution without any sudden changes in pH

Acids, Bases, and pH

An organic compound is a compound that usually contains carbonCarbon has 4 electrons in outer shell.Carbon can form 4 strong covalent bonds

usually with C, H, O, or N

Organic compounds in the body are often found as macromolecules which are made from thousands of smaller moleculesThe process of forming macromolecules is

called polymerization (small units called monomers join together to form polymers)

Organic Compounds

Examples:1. Carbohydrates2. Lipids3. Proteins4. Nucleic acids (DNA and

RNA)

Macromolecules

Energy is stored in the bonds that link these units together. The amount of energy stored in these bonds

varies with the type of molecule formed. As a result, not all organic molecules have the

same amount of energy available for use by the organism.

The energy stored in organic molecules determines its caloric value.

Proteins, carbohydrates, and fats/lipids are three organic molecules with different structures and different caloric values based on those structures.

Macromolecules

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Carbohydrates

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Carbohydrates

Small sugar molecules to large sugar molecules.

Examples:A. monosaccharideB. disaccharideC. polysaccharide

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Carbohydrates

Monosaccharide: one sugar unit

Examples: glucose (C6H12O6)

deoxyriboseriboseFructoseGalactose

glucose

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Carbohydrates

Disaccharide: two sugar unit

Examples: Sucrose (glucose+fructose)Lactose (glucose+galactose)Maltose (glucose+glucose)

glucoseglucose

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Carbohydrates

Polysaccharide: many sugar units

Examples: starch (bread, potatoes)

glycogen (beef muscle)

cellulose (lettuce, corn)

glucoseglucose

glucoseglucose

glucoseglucose

glucoseglucose

cellulose

Carbohydrates are important because they the main source of energy for the cell.When carbohydrates are synthesized (made) during

the process of photosynthesis, the plants or other photosynthetic organisms use them as a source of energy or they are stored in the cells.

When complex carbohydrates are consumed, the process of digestion breaks the bonds between the larger carbohydrate molecules so that individual simple sugars can be absorbed into the bloodstream through the walls of the intestines.The bloodstream carries the simple sugars to cells throughout

the body where they cross into the cells through the cell membrane.

Once inside the cells, simple sugars are used as fuel in the process of cellular respiration, releasing energy which is stored as ATP.

Carbohydrates

The caloric value of carbohydrates is dependent on the number of carbon-hydrogen bonds. If an organism has a greater supply of carbohydrates than needed for its energy requirements, the extra energy is converted to fats and stored by the body.

Carbohydrates

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Lipids

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LipidsGeneral term for compounds which are not

soluble in water.

Lipids are soluble in hydrophobic solvents.

“stores the most energy” fats contain more energy (ATP) per gram than carbohydrates or proteins, which explains why fats have a greater caloric value

Examples: 1. Fats2. Phospholipids3. Oils4. Waxes5. Steroid hormones6. Triglycerides

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LipidsFats (lipids) are important to organisms for energy

when carbohydrates are scarce since they are the primary way to store energy.

Six functions of lipids:1. Long term energy storage2. Protection against heat loss (insulation)3. Protection against physical shock (cushioning of vital organs)4. Protection against water loss5. Chemical messengers (hormones)6. Major component of membranes

(phospholipids)

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Lipids

Triglycerides:composed of 1 glycerol and 3

fatty acids. H

H-C----O

H-C----O

H-C----O

H

glycerol

O

C-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH3

=

fatty acids

O

C-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH3

=

O

C-CH2-CH2-CH2-CH =CH-CH2 -CH

2 -CH2 -CH

2 -CH3

=

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Fatty AcidsThere are two kinds of fatty acids you may see these on

food labels:

1. Saturated fatty acids: no double bonds (bad)

2. Unsaturated fatty acids: double bonds (good)

O

C-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH3

=

saturated

O

C-CH2-CH2-CH2-CH=CH-CH2 -CH

2-CH2 -CH

2 -CH3

=

unsaturated

When fats are consumed, the molecules are broken down during the process of digestion so that individual glycerol and fatty acid molecules are absorbed into the bloodstream through the walls of the intestines.

The blood stream carries the glycerol and fatty acid molecules to cells throughout the body where the molecules cross into the cells through the cell membrane.

Once inside the cell, glycerols and fatty acids are stored for later use or used as fuel for cellular respiration if there are no carbohydrates available.

The process of cellular respiration releases the energy that is held in the chemical bonds of the glycerol and fatty acid molecules

Lipids

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Proteins

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Proteins (Polypeptides)

Made up of Amino AcidsAmino acids (20 different kinds of aa) bonded

together by peptide bonds (polypeptides).

Twelve of these amino acids are made in the body; others must be consumed from foods such as nuts, beans, or meat.

Although proteins are more important as a source of building blocks, amino acids may be used by the body as a source of energy (through the process of cellular respiration), but first they must be converted by the body to carbohydrates. This process does not happen as long as there is a carbohydrate or lipid available.

As a source of energy, proteins have the same caloric value per gram as carbohydrates.

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Proteins (Polypeptides)

Six functions of proteins:1. Storage: albumin (egg white)2. Transport: hemoglobin3. Regulatory: hormones (ie insulin)4. Movement: muscles5. Structural: membranes, hair, nails6. Enzymes: cellular reactions

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Nucleic Acids

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Nucleic acidsTwo types:

a. Deoxyribonucleic acid (DNA- double helix)

b. Ribonucleic acid (RNA-single strand)

c. odd ball Adenosine Triphosphate (ATP)

Nucleic acids are composed of long chains of nucleotides.

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Nucleic acidsNucleotides include:

phosphate grouppentose sugar (5-carbon)nitrogenous bases:

adenine (A)thymine (T) DNA onlyuracil (U) RNA onlycytosine (C)guanine (G)

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Nucleotide

OO=P O O

Phosphate Group

NNitrogenous base (A, G, C, or T)

CH2

O

C1C4

C3 C2

5

Sugar(deoxyribose)

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DNA - double helix

P

P

P

O

O

O

1

23

4

5

5

3

3

5

P

P

PO

O

O

1

2 3

4

5

5

3

5

3

G C

T A

Chemical Reactions and

Enzymes

A chemical reaction is a process that changes one set of chemicals into another set of chemicals.Two Components of a Chemical Reaction:

1. Reactants – enter into the chemical reaction (on the left side of the yield)

2. Products – are produced/made by the chemical reaction (on the right side of the yield)

Example: H3PO4 + Mg(OH)2 => Mg3(PO4)2 + H2O

Chemical Reactions

biochemical reactions allow organisms to grow, develop, reproduce, and adapt. Sometimes a chemical reaction must absorb

energy for the reaction to start; often, but not always, this energy is in the form of heat.

Energy, as heat or light, can also be given off as a result of biochemical reactions, such as with cellular respiration or bioluminescence.

Chemical Reactions

Video Clip

Energy is released or absorbed whenever chemical bonds form or are broken.Example: heat

Exothermic Reaction – heat is releasedEndothermic Reaction – heat is absorbed

Most reactions need energy to get started. The amount of energy needed for a reaction to take place is called its activation energy.

Chemical Reactions

Catalyst – speed up the rate of a chemical reaction. (NOTE: Only time is affected amount and type of chemicals is not changed)Catalysts are able to speed up

the rate of a chemical reaction by lowering a chemical reaction’s activation energy.

Enzymes are proteins that act as biological catalystsCells use enzymes to speed up

chemical reactions that take place inside of them.

Chemical Reactions

Enzymes are very specific. Each particular enzyme can catalyze only one chemical reaction by working on one particular reactant (substrate).

Enzymes are involved in many of the chemical reactions necessary for organisms to live, reproduce, and grow, such as digestion, respiration, reproduction, movement and cell regulation.

The structure of enzymes can be altered by temperature and pH; therefore, each catalyst works best at a specific temperature and pH.

Chemical Reactions

Enzyme