Essentials of Biology - Chapter 3: The Organic Molecules of Life

Vocabulary flashcards reviewing key terms and concepts from Essentials of Biology, Chapter 3: The Organic Molecules of Life.

Organic molecules

Molecules that contain both carbon and hydrogen.

Inorganic molecules

Molecules that do not contain a combination of carbon and hydrogen, such as $H_2O$ and $NaCl$.

Carbon atom

An atom with a total of six electrons (four in its outer shell) that can bond with as many as four other elements and almost always shares electrons with elements such as hydrogen, nitrogen, and oxygen.

Hydrocarbons

Chains of carbon atoms bonded only to hydrogen atoms.

Isomers

Molecules that have the same number and kinds of atoms arranged in a variety of structures, which may possess different properties.

Carbon skeleton

The carbon backbone of an organic molecule, which varies in size and shape.

Functional group

A specific combination of bonded atoms that always has the same chemical properties and always reacts the same way, largely determining the reactivity of an organic molecule.

R

A symbol used in chemical structure diagrams to represent the remainder of the organic molecule attached to a functional group.

Hydroxyl group

A functional group ($-OH$) found in alcohols and sugars.

Carboxyl group

A functional group found in amino acids and fatty acids.

Amino group

A functional group containing nitrogen found in amino acids and proteins.

Sulfhydryl group

A functional group ($-SH$) found in the amino acid cysteine and in proteins.

Phosphate group

A functional group found in ATP and nucleic acids.

Categories of biological molecules

The four main classes of biological molecules: carbohydrates, lipids, proteins, and nucleic acids.

Monomers

Subunit molecules that serve as the building blocks for polymers.

Polymer

A large molecule created by joining multiple monomer subunits together.

Dehydration synthesis reaction

A chemical reaction that joins monomers to form polymers, equivalent to removing a water molecule.

Hydrolysis reaction

A chemical reaction used to break bonds in a polymer where an $OH$ group attaches to one monomer and an $H$ from water attaches to the other monomer.

Hydrocarbon Versatility

The structural diversity of carbon chains, which can vary in length, contain double bonds, be branched, or form rings of different sizes.

Common Functional Groups

Key combinations of bonded atoms—including hydroxyl, carboxyl, amino, sulfhydryl, and phosphate—that determine molecular reactivity and properties.