Introduction to Proteins and Amino Acids

Flashcards about proteins, amino acids, and their functions.

Proteins

Diverse organic molecules in living systems with varied structures and functions, more so than other macromolecules. They're made of one or more chains of amino acids.

Enzymes

Act as catalysts in biochemical reactions by speeding them up. Each one recognizes one or more substrates and may break down, link up, or rearrange their substrates.

Hormones

Long-distance chemical signals released by endocrine cells that control specific physiological processes, such as growth, development, metabolism, and reproduction.

Salivary amylase

Breaks amylose (a kind of starch) down into smaller sugars.

Insulin

An important peptide hormone that helps regulate blood glucose levels.

Digestive enzyme Role/ Examples~ Functions

• Break down nutrients.

• Amylase, lipase, and pepsin.

• Breaks down food into smaller pieces.

Transport Proteins Role/ Examples~Functions

• Carry substances throughout the body.

• Hemoglobin.

• Carries oxygen in the blood.

Structural Proteins Role/ Examples~Functions

• Build different structures.

• Actin, Tubulin, and Keratin.

• Forms the cytoskeleton.

Hormone signaling Proteins Role/ Examples~Functions

• Coordinate body systems.

• Insulin and Glucagon.

• Regulates bodily activities.

Defense Proteins Role/ Examples~Functions

• Protect the body from foreign pathogens.

• Antibodies.

• Provides immunity.

Contraction Proteins Role/ Examples~Functions

• Carry out muscle contraction.

• Myosin.

• Enables movement.

Storage Proteins Role/ Examples~Functions

• Provide food for the early development of an embryo or a seedling.

• Legume storage protein and albumin (found in egg whites).

• Supplies nourishment during initial growth stages.

Amino acids

Monomers that make up proteins. There are 20 types of amino acids.

polypeptide

A protein made up of one or more linear chains.

Denaturation

The process where changes in temperature and pH, as well as the presence of certain chemicals, may disrupt a protein’s shape and cause it to lose functionality

Each amino acid has a central alpha carbon bonded to:

• An amino group (NH2​)

• A carboxyl group (COOH)

• A hydrogen atom

• An R group (side chain)

R group (side chain)

Determines the identity and behavior of the amino acid. It also determines if the amino acid is acidic, basic, polar, or nonpolar.

Nonpolar, hydrophobic amino acids:

Valine, leucine

Polar, hydrophilic amino acids:

serine, glutamine

Basic amino acids (positively charged at physiological pH):

Lysine, arginine, and histidine.

Acidic amino acids (negatively charged at physiological pH):

Aspartate and glutamate.

Proline

The R group is linked back to its amino group, forming a ring structure that causes bends or kinks in amino acid chains.

Cysteine

Contains a thiol (-SH) group and can form covalent bonds with other cysteines.

Peptide Bonds

• Covalent bonds by which the amino acids of a polypeptide are attached to their neighbors.

• Each bond forms in a dehydration synthesis reaction, where the carboxyl group of one amino acid reacts with the amino group of another, releasing a molecule of water.

Polypeptide Chain

• A protein made up of one or more linear chains of amino acids linked together by peptide bonds. It has an amino terminus (N-terminus) and a carboxyl terminus (C-terminus).

• The chemical properties and order of the amino acids determine the structure and function of the polypeptide.

Amino terminus (N-terminus)

The end of a polypeptide with a free amino group.

Carboxyl terminus (C-terminus)

The end of a polypeptide with a free carboxyl group.