AP Biology Notes: Amino Acids, Enzymes, Collagen, Vitamin C, and Scurry (Scurvy)

Vocabulary flashcards covering key terms from amino acids, enzymes, collagen, and vitamin C/scurvy discussed in today’s lecture.

Amino acid

The building block of proteins; a molecule with an amino group (–NH2/–NH3+), a carboxyl group (–COOH/–COO−), a central carbon, and a variable side chain (R group).

Amino group

Nitrogen-containing group (–NH2 or –NH3+) in amino acids; called amine when free, amino when attached to a carbon skeleton.

Carboxyl group

–COOH group in amino acids; provides acidic H+ and is part of every amino acid’s backbone.

R group (side chain)

The variable group on an amino acid that determines its identity and chemical properties (size, polarity, charge).

Nonpolar amino acids

Amino acids with hydrophobic, mostly carbon-hydrogen side chains; tend to be nonpolar and cluster away from water.

Polar amino acids

Amino acids with polar side chains capable of hydrogen bonding; can be uncharged or carry a positive/negative charge.

Enzyme

A protein that speeds up a chemical reaction by lowering activation energy; usually ends with -ase.

Active site

The region of an enzyme where the substrate binds and the reaction occurs.

Substrate

The molecule that an enzyme acts upon (e.g., lactose as the substrate for lactase).

Lock-and-key model (complementary fit)

Concept that an enzyme and substrate must fit together with a precise shape and charge arrangement.

Lactase

Enzyme that hydrolyzes lactose; ends with -ase.

Sucrase

Enzyme that hydrolyzes sucrose; ends with -ase.

ATPase

Enzyme that hydrolyzes ATP; ends with -ase.

ATP synthase

Enzyme that synthesizes ATP (builds ATP from ADP and phosphate).

Insulin

A non-enzymatic protein; example of a protein ending in -in.

Collagen

Structural protein with a triple-helix; provides strength to connective tissues; requires vitamin C for proper hydroxylation and stability of its fibers.

Scurvy

Disease caused by vitamin C deficiency; leads to weak collagen, bruising, tooth loss, and gum problems.

Vitamin C (ascorbic acid)

Vitamin that acts as a cofactor in collagen hydroxylation; deficiency causes scurvy; helps enzymes add OH groups to collagen.

Vitamin C's role in collagen synthesis

Acts as a cofactor that enables hydroxylation of collagen precursors; without it, collagen strands can't form strong hydrogen-bond networks, leading to weak collagen.

Hydrogen bond

A weak attraction between a hydrogen atom bound to an electronegative atom (like O or N) and another electronegative atom; stabilizes collagen and proteins.

DNA as the blueprint for amino acids

DNA sequence encodes the order of amino acids in a protein; mutations can change folding and function.

Mutation

A change in DNA sequence that can alter amino acid sequence and protein folding, potentially changing function.

Lactose

Disaccharide sugar found in milk; substrate for lactase.

Acid/base definitions (Bronsted-Lowry)

Acids donate H+; bases accept H+; helps explain how amino acids ionize and how COOH can donate H+.

Enzyme naming convention (-ase)

Most enzymes end with -ase (e.g., lactase, sucrase, ATPase), indicating they catalyze a reaction.

Non-enzymes (-in, -en)

Some proteins end with -in or -en (e.g., insulin, collagen) and are not enzymes.

Triple helix (collagen)

Collagen structure composed of three intertwined peptide chains, giving high tensile strength to tissues.