Chemistry of Amino Acids

Vocabulary practice flashcards covering basic structure, stereochemistry, properties, and classifications of amino acids.

Biochemistry

The study of biomolecules and chemical processes and reactions within and relating to living organisms.

Biomolecules

Organic molecules provided by cells and living organisms that are essential to life, including carbohydrates, proteins, lipids, and nucleic acids.

Amino Acids

Organic compounds that serve as the building blocks of proteins, joined by cells in various combinations and sequences.

Alpha Carbon

The central carbon atom in an amino acid to which the amino group ($\text{-NH}_2$), carboxyl group ($\text{-COOH}$), hydrogen atom ($\text{H}$), and distinctive side chain ($\text{R}$ group) are bound.

Imino Acid

An amino acid derivative, such as proline, that possesses a secondary amino group (imino group) bound in a ring structure rather than a standard primary amino group.

Glycine

The simplest amino acid and the only non-chiral amino acid, because its side chain is a hydrogen atom, resulting in two identical hydrogen atoms bound to the alpha carbon.

Chirality of Amino Acids

The property of having non-superimposable mirror images ($\text{D}$ or $\text{L}$ stereoisomers) due to four different functional groups attached to the central alpha carbon.

Aliphatic Amino Acids

Amino acids whose side chains contain exclusively carbon and hydrogen atoms, including glycine, alanine, valine, leucine, and isoleucine.

Sulfur-Containing Amino Acids

Amino acids that contain a sulfur atom in their side chain structure, specifically cysteine and methionine.

Aromatic Amino Acids

Amino acids containing an aromatic ring in their side chain structure, including phenylalanine, tyrosine, and tryptophan.

Acidic Amino Acids

Amino acids carrying a net negative charge at physiological $\text{pH} = 6$, comprising aspartic acid (Asp, D) and glutamic acid (Glu, E).

Basic Amino Acids

Amino acids carrying a net positive charge at physiological $\text{pH} = 6$, comprising lysine (Lys, K), arginine (Arg, R), and histidine (His, H).

Essential Amino Acids

Amino acids that cannot be synthesized by the human body and must be supplied by the diet to maintain normal growth and nitrogen balance (mnemonic: PVT TIM HALL).

Non-Essential Amino Acids

Amino acids that can be synthesized in adequate quantities by the human body and do not need to be provided through dietary sources.

Semi-Essential Amino Acids

Amino acids synthesized in the body, but in amounts insufficient to meet metabolic demands during growth or positive nitrogen balance (e.g., histidine and arginine).

Metabolic Classification of Amino Acids

Classification based on the fate of the carbon skeleton: ketogenic (lysine and leucine), glucogenic (glucose precursors), or both ketogenic and glucogenic (isoleucine, phenylalanine, threonine, tryptophan, tyrosine).