Chapter 3: Molecules of Life

Vocabulary flashcards derived from Chapter 3 notes on biological molecules, their structures, and metabolic processes.

Cis fats

Most naturally occurring fats.

Trans fats

Unhealthy fats found mostly in partially hydrogenated vegetable oils, linked to diabetes, heart attacks, and atherosclerosis in humans.

Organic compound

A compound that consists mostly of carbon and hydrogen.

Hydrocarbon

A nonpolar compound consisting of only carbon and hydrogen.

Functional group

An atom or small molecular group bonded to a carbon in an organic compound that impacts chemical properties such as acidity or polarity.

Monomers

Small organic molecules used as subunits to build larger molecules (polymers).

Polymers

Larger molecules composed of chains of monomers, which may be split and used for energy.

Metabolism

Activities by which cells acquire and use energy to construct, rearrange, and split organic molecules.

Enzymes

Proteins that increase the speed of chemical reactions.

Hydrolysis

A reaction in which enzymes remove monomers from polymers.

Condensation

A reaction in which enzymes join one monomer to another; also called dehydration.

Carbohydrates

The most abundant biological molecules, composed of carbon, hydrogen, and oxygen in a 1:2:1 ratio, used for structural materials, fuels, and storing/transporting energy.

Monosaccharides

Simple carbohydrates consisting of 1 sugar unit with a carbon backbone and carbonyl and hydroxyl functional groups that are soluble in water.

Oligosaccharides

Short-chain carbohydrates composed of a few monosaccharides.

Disaccharides

Short-chain carbohydrates consisting of two sugar units, such as lactose and sucrose.

Polysaccharides

Complex carbohydrates consisting of hundreds or thousands of monosaccharides in straight or branched chains.

Chitin

A durable, translucent, and flexible structural polysaccharide composed of long, unbranching chains of nitrogen-containing sugar monomers linked by hydrogen bonds.

Saturated fatty acids

Fatty acids with straight hydrocarbon tails containing only single bonds.

Unsaturated fatty acids

Fatty acids with crooked hydrocarbon tails containing double bonds.

Triglycerides

Lipids with three fatty acid tails bound to a glycerol head, serving as the most abundant and richest energy sources in vertebrates.

Phospholipids

Lipids with two hydrophobic hydrocarbon tails bound to a hydrophilic phosphate-containing head, arranged in two layers to form cell membrane lipid bilayers.

Waxes

Complex mixtures with long fatty-acid tails bonded to long-chain alcohols or carbon rings that form a protective, water-repellant covering.

Steroids

Lipids with a rigid backbone of four carbon rings and no fatty-acid tails.

Cholesterol

The most important steroid in animal tissue, serving as a component of eukaryotic cell membranes and remodeled into bile salts, vitamin D, and steroid hormones.

Amino acids

Small organic molecules composed of a central carbon bonded to an amine group, a carboxyl group, and a variable R group, serving as the monomers for proteins.

Primary structure

The unique sequence of amino acids in a protein.

Secondary structure

The structural level of a protein where the polypeptide chain folds and forms hydrogen bonds, forming a helix or a sheet.

Tertiary structure

The level of protein structure where secondary structures compact into structurally stable units called domains, forming a functional protein.

Quaternary structure

The structural level of a protein consisting of two or more folded polypeptide chains in close association.

Glycoprotein

A protein with one or more oligosaccharides attached to it.

Lipoprotein

A protein that can bind to lipids.

Prions

Misfolded proteins that cause infectious diseases characterized by deterioration of mental and physical abilities.

Nucleotides

Small organic molecules composed of ribose bonded to a nitrogen-containing base and one, two, or three phosphate groups.

Nucleic acids

Polymers of nucleotides in which the sugar of one nucleotide is attached to the phosphate group of the next.

RNA

A nucleic acid consisting of four kinds of nucleotide monomers, including ATP, that plays an important role in protein synthesis.

DNA

A nucleic acid consisting of two chains of nucleotides twisted together into a double helix and held by hydrogen bonds, containing all inherited information necessary to build an organism.