Amino Acids, Peptides, Proteins

These flashcards cover key concepts related to amino acids, peptides, proteins, their structures, functions, and biochemical properties.

Amino Acids

Building blocks of proteins, characterized by an alpha carbon bonded to an amino group, carboxyl group, hydrogen, and a variable side chain (R).

Post-translational modification

Chemical modifications that occur to amino acids in proteins after translation, affecting their function and activity.

Zwitterion

A form of amino acids at neutral pH where they have both a positive and a negative charge, resulting in a net charge of zero.

Cationic form

The state of amino acids at acidic pH where the carboxyl group is protonated.

Directional N→C manner

The orientation in which amino acids link via peptide bonds, defining the structure of peptides/proteins.

Chirality

The property of amino acids (except glycine) that allows them to exist in two mirror-image forms.

LUCA (Last Universal Common Ancestor)

The most recent common ancestor of all current life on Earth, estimated to have existed around 4.2 billion years ago.

Peptide bond

A covalent bond formed between two amino acids through a condensation reaction, linking the carboxyl group of one amino acid to the amino group of another.

Nonpolar, aliphatic R groups

A category of amino acid side chains that are hydrophobic and do not interact favorably with water.

Ionization behavior

The behavior of amino acids in different pH environments that affects their charge state and solubility.

Proteins

Large biomolecules made up of one or more polypeptides folded into a unique 3D structure, functioning primarily as catalysts, transporters, structural elements, and mediators of movement.

Catalysis

The acceleration of a chemical reaction by a catalyst, a role often performed by certain proteins in biochemical pathways.

Aromatic R groups

Side chains containing aromatic rings that can absorb UV light, categorized as a type of side chain in amino acids.

Positively charged R groups

A category of amino acids that gain a positive charge at physiological pH, playing roles in various biochemical interactions.

Negatively charged R groups

A category of amino acids that carry a negative charge at physiological pH, often involved in enzyme catalysis.

Peptide

A chain of amino acids linked by peptide bonds, usually shorter than 10 kDa compared to proteins.