CH2 CHEM PT 4 - PROTEINS -Proteins and Amino Acids: Key Concepts-

Vocabulary flashcards covering amino acids, peptide bonds, protein structure levels, denaturation, and protein function (enzymes, hemoglobin, collagen, etc.).

Amino acid

The building block of proteins; contains carbon, hydrogen, oxygen, nitrogen; sometimes sulfur; has an R group; about 20 types in the body; can be polar or nonpolar; some are essential in the diet.

R group (side chain)

The variable chemical group attached to an amino acid that determines its identity and properties; varies among the ~20 amino acids.

Peptide bond

Covalent bond joining two amino acids; formed by dehydration synthesis (removal of water).

Dehydration synthesis

Condensation reaction that removes water to join monomers (e.g., amino acids) into polymers.

Primary structure

Linear sequence of amino acids in a protein; determined by DNA; codes for the protein.

Secondary structure

Local folding patterns in a polypeptide, commonly alpha helix or beta-pleated sheet.

Alpha helix

Right-handed helical secondary structure stabilized by hydrogen bonds along the backbone.

Beta-pleated sheet

Secondary structure with strands laid out in a zigzag pleated arrangement stabilized by inter-strand hydrogen bonds.

Tertiary structure

Three-dimensional folding of a single polypeptide; gives the protein its unique shape and function; driven by interactions among side chains.

Quaternary structure

Assembly of two or more polypeptide chains into a functional protein.

Globular protein

Compact, roughly spherical, usually water-soluble proteins (often enzymes or regulators).

Fibrous protein

Long, thread-like proteins providing structural support (e.g., collagen, elastin).

Denaturation

Unfolding of a protein from its tertiary structure; loss of function; caused by heat or pH changes; can be reversible or irreversible.

Enzyme

Protein that acts as a biological catalyst; speeds up specific reactions without being consumed; often ends with -ase.

Catalyst

Substance that increases the rate of a chemical reaction without being consumed; enzymes are biological catalysts.

Carbonic anhydrase

Enzyme that catalyzes the conversion between carbonic acid and bicarbonate plus a proton.

Lactase

Enzyme that catalyzes the breakdown of lactose into glucose and galactose.

Hemoglobin

Quaternary protein with four chains that binds and transports oxygen; mutations can impair function (e.g., sickle cell anemia).

Sickle cell anemia

Genetic disorder caused by a single amino acid substitution in hemoglobin, altering structure and oxygen transport.

Collagen

Fibrous structural protein in connective tissue that provides strength.

Insulin

Protein with a defined primary structure (sequence of amino acids) used as an example of a known protein.

Essential amino acids

Subset of amino acids that must be obtained from the diet; about 10 in humans.

Nonessential amino acids

Amino acids that can be synthesized by the body; about 10.

DNA

Nucleic acid that codes for the primary structure of proteins; does not contain amino acids.