Proteins

Macromolecule

Large molecules made of amino acid monomers.

Amino Acid Structure

Consists of a central carbon bonded to a carboxyl group, an amino group, an 'R' group, and an H atom.

R Group

The variable group in an amino acid that determines its properties; can be hydrophobic or hydrophilic.

Nonpolar R Groups

R groups that are hydrophobic and do not interact well with water.

Polar R Groups

R groups that are hydrophilic and interact well with water.

Peptide

A polymer consisting of two or more amino acids.

Dipeptide

A peptide consisting of two amino acids.

Tripeptide

A peptide consisting of three amino acids.

Oligopeptide

A peptide consisting of fewer than 10 to 15 amino acids.

Polypeptide

A peptide consisting of more than 15 amino acids.

Protein

A large molecule made of one or more polypeptides, typically having more than 100 amino acids.

Dehydration Synthesis

A chemical process that creates peptide bonds by removing a water molecule.

Primary Structure

The linear sequence of amino acids in a protein.

Secondary Structure

Interactions among amino acids that cause the chain to coil into an alpha helix or fold into a beta pleated sheet.

Tertiary Structure

The overall three-dimensional shape of a protein formed by interactions among amino acids.

Quaternary Structure

The interaction of multiple polypeptides to form a functional protein.

Conformation

The overall 3-D shape of a protein, crucial to its function.

Denaturation

The drastic conformational change that destroys the function of a protein, often caused by extreme heat or pH.

Protein Functions

Includes structure (e.g., collagen, keratin), communication (e.g., hormones, receptors), membrane transport, and catalysis (e.g., enzymes).