Biological Molecules: The Carbon Compounds of Life

Vocabulary flashcards covering fundamental concepts, definitions, and structures from Chapter 3 on biological molecules.

Organic molecules

Most complex molecules based on carbon.

Inorganic molecules

Substances not based on carbon, including a few small carbon-containing molecules such as $CO_2$.

Hydrocarbons

Molecules consisting of carbon linked only to hydrogen atoms.

Chemical evolution

The process resulting in the first forms of life on Earth through reactions involving inorganic molecules on primordial Earth.

Functional groups

Small, reactive groups of atoms that give larger molecules specific chemical properties.

Isomers

Molecules that have the same chemical formula but different molecular structures.

Stereoisomers

Isomers that are mirror images of each other, typically occurring as L-form or D-form.

Structural isomers

Molecules with the same chemical formula whose atoms are arranged in different ways.

Dehydration synthesis reaction

A condensation reaction in which components of a water molecule ($-H$ and $-OH$) are removed as functional groups interact.

Hydrolysis

A reaction in which components of a water molecule ($-H$ and $-OH$) are added to break polymers down into monomers.

Macromolecule

A single polymer molecule with a mass of $1,000\,Da$ (daltons) or more.

Monosaccharides

Carbohydrate monomers containing three to seven carbon atoms that are soluble in water and sweet tasting.

Polysaccharides

Carbohydrate polymers with more than 10 linked monosaccharide monomers.

Disaccharides

Carbohydrates assembled from two monosaccharides covalently joined by a dehydration synthesis reaction.

Glycosidic bond

A covalent linkage formed between monosaccharides with oxygen acting as a bridge.

Neutral lipids

Nonpolar energy-storage lipids that have no charged groups.

Triglycerides

Lipids formed by dehydration synthesis between three-carbon glycerol and three fatty acid side chains.

Ester linkage

A covalent bond formed between the $-COOH$ group of a fatty acid and the $-OH$ group of glycerol.

Saturated fatty acid

A fatty acid with only single bonds between carbon atoms that binds the maximum number of hydrogen atoms.

Unsaturated fatty acid

A fatty acid containing one or more double bonds between carbon atoms.

Waxes

Lipids formed by fatty acids combined with long-chain alcohols or hydrocarbon structures, making them harder and less greasy than fats.

Phospholipids

Primary lipids of cell membranes, composed of a glycerol backbone linked to two fatty acid chains and a polar phosphate group.

Phospholipid bilayer

A film of phospholipids two molecules thick that forms the structural basis of cell membranes.

Steroids

Lipids structured around a framework of four carbon rings.

Amino acids

Monomers of proteins, containing a central carbon atom attached to an amino group, a carboxyl group, a hydrogen atom, and a variable R group.

Peptide bond

A covalent bond formed by a dehydration synthesis reaction between the $-NH_2$ group of one amino acid and the $-COOH$ group of another.

Primary structure

The unique sequence of amino acids forming a polypeptide chain.

Secondary structure

The structural level produced by the twists and turns of an amino acid chain.

Tertiary structure

The overall 3-D shape of a protein resulting from the folding of the amino acid chain and its secondary structures.

Quaternary structure

The protein structure formed when a functional protein is composed of more than one polypeptide chain.