Protein Structure and Function

Vocabulary flashcards covering key terms related to protein structure and function as discussed in the lecture notes.

Proteins

Account for more than 50% of the dry mass of most cells and include a diversity of structures, resulting in a wide range of functions such as defense, storage, transport, cellular communication, movement, and structural support.

Enzymatic proteins

Selective acceleration of chemical reactions (e.g., digestive enzymes).

Defensive proteins

Protection against disease (e.g., antibodies).

Storage proteins

Storage of amino acids (e.g., casein in milk, ovalbumin in egg white).

Transport proteins

Transport of substances (e.g., hemoglobin transports oxygen).

Hormonal proteins

Coordination of an organism’s activities (e.g., insulin regulates blood sugar).

Receptor proteins

Response of cell to chemical stimuli.

Contractile and motor proteins

Movement (e.g., actin and myosin in muscles).

Structural proteins

Support (e.g., keratin in hair, collagen and elastin in connective tissues).

Polypeptides

Unbranched polymers built from the same set of 20 amino acids.

Protein

A biologically functional molecule that consists of one or more polypeptides.

Amino acids

Are simultaneously acids and bases = amphoteric.

Peptide bonds

Link amino acids together to form a polypeptide.

Polypeptide

A polymer of amino acids, ranging in length from a few to more than a thousand monomers, with a unique linear sequence of amino acids, with a carboxyl end (C-terminus) and an amino end (N-terminus).

Primary Structure

The linear chain of amino acids in a protein.

Secondary Structure

Regions stabilized by hydrogen bonds between atoms of the polypeptide backbone, such as α helices and β pleated sheets.

Tertiary Structure

Three-dimensional shape stabilized by interactions between side chains (R groups).

Quaternary Structure

Association of two or more polypeptides (some proteins only).

α helices

A type of secondary protein structure characterized by a helical shape, stabilized by hydrogen bonds.

β pleated sheets

A type of secondary protein structure characterized by strands connected laterally by hydrogen bonds, forming a pleated sheet.

R groups

Side chains of amino acids that determine the tertiary structure of a protein through various interactions.

Denaturation

The loss of a protein's native structure, leading to loss of function.

Chaperones

Proteins that protect newly synthesized proteins from inappropriate interactions and allow them to fold properly.

Hydrophobic interaction

Amino acids with hydrophobic (nonpolar) side chains usually end up in the core of the protein.

Disulphide bridges

Can form between the sulfurs of two cysteines and contribute to tertiary protein structure.