Lipids, Proteins, Enzymes, and Nucleic Acids Vocabulary

Comprehensive vocabulary flashcards covering lipids, proteins, protein structure levels, enzymes, and nucleotides from the lecture notes.

Lipids

Hydrophobic organic molecules with a high ratio of hydrogen to oxygen that yield more calories per gram than carbohydrates.

Fatty acids

Chains of 4 to 24 carbon atoms with a carboxyl group on one end and a methyl group on the other.

Essential fatty acids

Fatty acids that cannot be synthesized by the human body and must be obtained from food.

Saturated fatty acid

A fatty acid whose carbon atoms are linked entirely by single covalent bonds, containing as much hydrogen as possible.

Unsaturated fatty acid

A fatty acid containing double bonds between carbon atoms, leaving potential to add more hydrogen atoms.

Polyunsaturated fatty acids

Fatty acids that contain multiple double bonds between carbon atoms.

Triglycerides

Molecules composed of three fatty acids linked to a glycerol molecule via dehydration synthesis; also known as neutral fats.

Oils

Plant-derived polyunsaturated triglycerides that are usually liquid at room or body temperature.

Saturated fats

Animal-derived saturated triglycerides that are solid at room or body temperature.

Trans fat

A triglyceride containing one or more trans-fatty acids where C-C single bonds angle in opposite directions across a C=C double bond.

Phospholipids

Amphipathic lipids similar to triglycerides, but with one fatty acid replaced by a phosphate group, forming the structural foundation of cell membranes.

Amphipathic

Molecules possessing both hydrophobic regions (such as fatty acid tails) and hydrophilic regions (such as a phosphate head).

Eicosanoids

20-carbon compounds derived from arachidonic acid that act as hormone-like chemical signals between cells.

Prostaglandins

A class of eicosanoid chemical signals involved in inflammation, blood clotting, hormone action, labor contractions, and blood vessel diameter.

Steroids

Lipids characterized by 17 carbon atoms arranged in four rings.

Cholesterol

The parent steroid from which other steroids are synthesized, essential for nervous system function and structural integrity of cell membranes.

Lipoprotein

Droplets in the blood that consist of complexes of cholesterol, fat, phospholipid, and protein.

HDL (high-density lipoprotein)

Lipoprotein known as good cholesterol that has a lower ratio of lipid to protein and may help prevent cardiovascular disease.

LDL (low-density lipoprotein)

Lipoprotein known as bad cholesterol that has a high ratio of lipid to protein and contributes to cardiovascular disease.

Protein

A biological polymer composed of amino acid monomers.

Amino acid

A molecule containing a central carbon attached to an amino group ($\text{-NH}_2$), a carboxyl group ($\text{-COOH}$), and a unique radical (R) group.

Peptide bond

A covalent bond formed by dehydration synthesis that joins the amino group of one amino acid to the carboxyl group of another.

Oligopeptides

Peptides composed of fewer than 10 to 15 amino acids.

Polypeptides

Peptides composed of larger than 15 amino acids.

Conformation

The unique three-dimensional shape of a protein that is crucial to its biological function.

Denaturation

An extreme conformational change in a protein that destroys its function, often caused by extreme heat or pH.

Primary structure

The sequence of amino acids within a protein molecule, encoded directly by genes.

Secondary structure

A coiled or folded protein shape held together by hydrogen bonds between C=O and -NH groups.

Alpha helix

A springlike secondary structure shape of a protein.

Beta sheet

A folded, ribbonlike secondary protein structure, also known as a beta-pleated sheet.

Tertiary structure

The bending and folding of proteins into globular or fibrous shapes due to hydrophobic-hydrophilic interactions, van der Waals forces, and disulfide bridges.

Disulfide bridges

Covalent bonds between cysteine amino acids that stabilize a protein's tertiary structure.

Quaternary structure

Structure formed by associations of two or more polypeptide chains held together by ionic bonds and hydrophobic-hydrophilic interactions.

Ligands

Signaling molecules that exert their effects by reversibly binding to a receptor protein.

Enzymes

Proteins that function as biological catalysts to speed up chemical reactions.

Ribozymes

Enzymes composed of RNA that are found in ribosomes.

Substrates

The specific reactant molecules upon which an enzyme acts.

Activation energy

The energy needed to get a chemical reaction started.

Active site

A pocket on an enzyme where substrate molecules bind to form an enzyme-substrate complex.

Nucleotides

Organic compounds composed of three components: a nitrogenous base, a monosaccharide sugar, and one or more phosphate groups.