CHEM 102 Lecture Notes on Proteins and Amino Acids

Flashcards covering the key vocabulary and definitions from the provided CHEM 102 lecture notes on proteins, amino acids, and their structures.

Proteins

Naturally occurring unbranched polymers of amino acids connected together by peptide bonds.

Fibrous proteins

Proteins that are the main structural material for animals, e.g. collagen and keratin; insoluble in water.

Enzymes

Proteins that catalyze almost all the reactions that take place in living organisms.

Globular proteins

Proteins that are more or less soluble in water and are used mainly for non-structural purposes.

Amino Acid

An organic compound containing a carboxyl group (-COOH) and amino group (-NH2) at the same time.

Alpha Amino Acid

Amino acids whose carboxyl group and amino group are attached to a common carbon, known as the alpha carbon.

Essential Amino Acids

Amino acids that the body cannot adequately synthesize and must be obtained from dietary sources.

Arginine

An essential amino acid that is only essential for infants for normal growth, it becomes nonessential as they grow into adulthood.

Complete Dietary Protein

A protein that contains all the essential amino acids in adequate amounts as the body needs them.

Incomplete Dietary Protein

A protein that does not contain in adequate amounts, relative to the body’s needs, of one or more of the essential amino acids.

Limiting Amino Acid

The essential amino acid that is missing or present in an inadequate amount in an incomplete dietary protein.

Complementary Dietary Protein

Proteins from rice and beans when eaten together.

Zwitterion

An ion with both positive and negative charges.

Peptide

A compound containing two or more amino acids where the carboxyl group of one amino acid condenses with the amino group of another.

Oxytocin

Regulates uterine contraction and lactation; also called the love hormone.

Vasopressin

A peptide that regulates the excretion of water in kidneys and affects blood pressure; also called antidiuretic hormone.

Glutathione

A peptide present in significant concentrations in most cells which serves as an antioxidant.

Protein

Polypeptides with a large number of amino acid residues, usually more than 40 residues.

Simple Proteins

Proteins containing only amino acid residues.

Conjugated Proteins

Proteins that contain non-amino acid groups known as prosthetic groups.

Isoelectric Point

The pH at which a protein is least soluble in water.

Native Conformation

Three-dimensional structure of a protein with biological function.

Primary Structure of Proteins

The number, kind, and sequence of amino acids in a protein.

Secondary Structure of Proteins

Regular localized arrangement of polypeptide backbone arrangement, stabilized by hydrogen bonds.

A-helix

A spiral, repeating structure of a polypeptide chain, maintained by hydrogen bonds.

B-Pleated Sheets

The peptide backbone of two protein chains held together by hydrogen bonds.

Turns and Loops

Reversals in the direction of polypeptide chains.

Tertiary Structure

The overall three-dimensional structure of proteins, also known as folding.

Quaternary Structure

The non-covalent association of protein subunits into a supramolecule in a multimeric protein.

Allosteric Proteins

Proteins that have quaternary structures, and when subtle changes in structure at one site may cause drastic changes in properties at a distant site.

Protein Hydrolysis

Disruption of the peptide bonds causing liberation of free amino acids.

Protein Denaturation

Disruption (unfolding) of a protein’s three-dimensional structure due to the breakdown of the non-covalent interaction causing loss of biological activity.