AP BIO CHAPTER 4

Organic chemistry

Study of compounds containing carbon; key to the origin of life

Range of organic compounds

Simple molecules to very large ones

Stanley Miller’s experiment

Demonstrated abiotic synthesis of organic compounds, supporting origin of life theories

Abiotic synthesis

Possibly occurred near volcanoes; stage in the origin of life

Major elements of life

C, H, O, N, S, and P; percentages are uniform across organisms

Versatility of carbon

Due to its ability to form 4 bonds, carbon can build diverse organic molecules

Electron configuration

Key to an atom’s chemical characteristics; determines bonding capacity

Carbon bonding

Has 4 valence electrons → forms 4 covalent bonds; enables large, complex molecules

Carbon tetrahedral shape

Carbon bonded to 4 atoms forms a tetrahedral structure

Double-bonded carbons

Atoms joined lie in the same plane as carbons

Valence

Number of unpaired electrons in valence shell = number of covalent bonds atom can form

Carbon’s bonding partners

Hydrogen, oxygen, nitrogen (most common)

Carbon skeletons

Chains of carbon atoms; vary in length and shape; form most organic molecules

Hydrocarbons

Molecules made of only carbon and hydrogen; can release large amounts of energy

Isomers

Compounds with same formula but different structures/properties

Structural isomers

Differ in covalent arrangements

Cis-trans isomers

Have same covalent bonds but differ in spatial arrangement

Enantiomers

Isomers that are mirror images; often only one is biologically active

Enantiomers in pharmaceuticals

Two enantiomers may have different biological effects

Distinctive properties

Depend on carbon skeleton + chemical groups attached

Functional groups

Specific groups of atoms involved in chemical reactions; give molecules unique properties

Sex hormones

(Example: estradiol vs. testosterone) differ only in attached functional groups

Seven functional groups

Hydroxyl, carbonyl, carboxyl, amino, sulfhydryl, phosphate, methyl

ATP

Organic phosphate: adenosine + 3 phosphate groups

ATP function

Stores potential energy; reacts with water to release usable energy

Carbon’s bonding limit

Can form only 4 bonds

Ethanol

Example of a simple organic molecule

Molecular diversity

Due to variation in carbon skeletons and chemical groups

Biological diversity

Variation at molecular level lies at the foundation of all life diversity