MCB Unit 2 Chapter 6: Proteins

Protein

Molecules that control metabolism, transport, communication, structure, division, and more.

Amino Acid

Building blocks of proteins—contain a central carbon bonded to an amino group, carboxyl group, hydrogen atom, and a variable side chain.

Polypeptide

A polymer of amino acids that folds into a functional protein.

Denature

The process by which a protein unfolds and loses its function.

Primary Structure

The sequence of amino acids in a polypeptide chain.

Secondary Structure

Regular patterns of folding in a polypeptide, such as alpha helices and pleated sheets.

Tertiary Structure

The overall 3D shape of a protein, resulting from the folding of the polypeptide chain.

Globular Protein

Proteins that are round or irregular in shape, often soluble and functional.

Fibrous Protein

Proteins that are long and cable-like, providing structure and support.

Covalent Bond

A strong bond formed between atoms when they share electrons, such as disulfide bridges in proteins.

Peptide Bond

The covalent bond formed between two amino acids during protein synthesis.

Enzyme

Biological catalysts that speed up chemical reactions.

Competitive Inhibition

Inhibition where a molecule similar to the substrate competes for binding at the active site.

Noncompetitive Inhibition

Inhibition where a regulatory molecule binds to an allosteric site, altering the enzyme's activity.

Cofactor

Inorganic molecule required for enzyme activity.

Coenzyme

Organic molecule, often derived from vitamins, required for enzyme activity.

Feedback Inhibition

Regulatory mechanism in which the end product of a pathway inhibits an upstream process.

Ligand

A chemical signal that binds to a receptor protein on a cell's surface.

DNA-binding Proteins

Proteins that bind to DNA and regulate which parts are read or silenced.

Helix Turn Helix Motif

A structural motif in DNA-binding proteins consisting of two alpha helices linked by a short turn.

Zinc Finger Motif

A structural motif in DNA-binding proteins involving an alpha helix and two pleated sheets held together by a zinc atom.

Leucine Zipper Motif

A structural motif consisting of two alpha helices held together by hydrophobic interactions, common in eukaryotic DNA-binding proteins.