Structure and Chemical Properties of Amino Acids

A comprehensive set of flashcards covering key vocabulary and concepts related to the structure and chemical properties of amino acids and their roles in biochemistry.

Amino acids

Organic compounds that serve as the building blocks of proteins.

Zwitterion

A molecule that has both positive and negative electrical charges, thus being neutral overall.

Isoelectric point (pI)

The specific pH at which an amino acid has no net charge.

Peptide bond

The covalent bond formed between the carboxyl group of one amino acid and the amino group of another.

Proton donor

A substance that can donate a hydrogen ion (H+) in a chemical reaction; generally referred to as an acid.

Proton acceptor

A substance that can accept a hydrogen ion (H+) in a chemical reaction; generally referred to as a base.

Polypeptide

A chain of multiple amino acids linked by peptide bonds.

Dipeptide

A molecule consisting of two amino acids linked by a peptide bond.

Tripeptide

A molecule consisting of three amino acids linked by peptide bonds.

Oligopeptide

A short chain of amino acids, usually comprising 2 to 10 amino acids.

Macropeptide

A peptide containing more than 100 amino acids.

Ionizable group

A functional group that can accept or donate protons, thus changing the molecular charge.

Hydrogen bond

A weak attraction between a hydrogen atom bound to a highly electronegative atom, like oxygen or nitrogen, and another electronegative atom.

Cation

A positively charged ion.

Anion

A negatively charged ion.

Titration

The process of determining the concentration of a soluble substance by adding a known reactant.

Alpha-carboxyl group

A group (-COOH) found in amino acids that has acidic properties.

Alpha-amino group

A group (-NH2) found in amino acids that has basic properties.

pKa value

The pH at which a particular acidic group is half dissociated; a measure of acid strength.

Condensation reaction

A chemical reaction where two molecules combine to form a larger molecule with the elimination of water.

Hydrolysis reaction

A reaction where water is added to split a compound into smaller molecules.

Transamination

The transfer of an amino group from one molecule to another.

Decarboxylation

The removal of a carboxyl group from a molecule.

Proteins

Large biomolecules made up of one or more long chains of amino acid residues.

Buffer

A system that minimizes changes in pH upon the addition of small quantities of acids or bases.

Weak acid

An acid that does not completely dissociate in solution.

Weak base

A base that does not fully ionize in solution.

Inter-conversion

The process in which two different forms can be converted into each other.

pK₁

The dissociation constant for the carboxyl group in an amino acid.

pK₂

The dissociation constant for the amino group in an amino acid.

Aliphatic side chains

Side chains in amino acids that consist of straight or branched chain hydrocarbons.

Aromatic side chains

Side chains that contain aromatic rings; generally non-polar.

Polar uncharged amino acids

Amino acids that have polar side chains but do not carry a charge at physiological pH.

Negatively charged amino acids

Amino acids that have side chains capable of donating protons, thus becoming negatively charged.

Positively charged amino acids

Amino acids that carry a positive charge due to their side chains at physiological pH.

Structural integrity

The overall condition or robustness of a protein's structure.

Titration curve

A graph that represents how the pH of a solution changes as acid or base is added.

Cis and trans conformations

Two different structural forms of a molecule that can interconvert.

Digestion of proteins

The process by which dietary proteins are broken down into amino acids in the gastrointestinal tract.

Energy transformation

The conversion of energy from one form to another in biochemical processes.

Urea cycle

The process by which excess nitrogen from amino acids is removed from the body in the form of urea.

Ammonia detoxification

The conversion of toxic ammonia into urea or other less harmful substances.

Alpha-ketoacid

An organic compound that contains a keto group and an alpha position relative to the carboxylic acid.

Catecholamine synthesis

The biochemical process that produces catecholamines, such as dopamine and norepinephrine, from amino acids.

Glycine

The simplest amino acid with a neutral side chain, often involved in various metabolic processes.

Valine

An essential branched-chain amino acid crucial for protein synthesis.

Leucine

A branched chain essential amino acid important for muscle repair.

Methionine

An essential amino acid that serves as a starting point for protein synthesis.

Phenylalanine

An essential amino acid that is a precursor to tyrosine.

Tryptophan

An essential amino acid used to synthesize serotonin.

Histidine

An essential amino acid that plays a role in enzyme activity.

Lysine

An essential amino acid important for proper growth.

Arginine

A semi-essential amino acid that aids in protein synthesis and immune function.

Aspartic acid

A non-essential amino acid involved in the biosynthesis of other amino acids.

Glutamate

A non-essential amino acid important for cellular metabolism.

Peptide naming

The convention for naming peptides based on their amino acid sequences.

Free amino end

The N-terminal end of a polypeptide chain with a free amino group.

Free carboxyl end

The C-terminal end of a polypeptide chain with a free carboxyl group.

Peptide synthesis

The process of forming peptides by linking amino acids together.

Digestive enzymes

Enzymes that catalyze the breakdown of food proteins into amino acids.

pH

A measure of the acidity or basicity of a solution.

Peptide bond hydrolysis

The breaking of peptide bonds through the addition of water.

Biochemical reactions

Chemical processes that occur in living organisms involving biomolecules.

Amino acid metabolic conversions

Biochemical pathways in which amino acids are transformed into other compounds.