(8) Amino acid structure | Chemical processes | MCAT | Khan Academy

Amino Acids

The building blocks of proteins, consisting of a central carbon bonded to an amino group, a carboxylic acid group, a hydrogen atom, and a unique side chain (R group).

Hemoglobin

A protein found in red blood cells that carries oxygen from the lungs to tissues and returns carbon dioxide from the tissues to the lungs.

Alpha Carbon

The central carbon atom in an amino acid that is bonded to four different groups, making it a chiral carbon.

Chirality

A property of a carbon atom that has four different groups attached, resulting in two non-superimposable mirror images.

Glycine

The simplest amino acid with a side chain that is just a hydrogen atom; it is the only amino acid that is not chiral.

Fischer Projection

A two-dimensional representation of a molecule that illustrates the arrangement of groups around a chiral carbon.

L-Amino Acid

The configuration of amino acids in which the amino group is on the left side in Fischer projections; the only form found in human proteins.

D-Amino Acid

The mirror-image configuration of amino acids; the amino group is on the right side in Fischer projections, not typically found in humans.

Enantiomers

Molecules that are mirror images of each other and are not superimposable.

Side Chain (R Group)

The unique group attached to the alpha carbon of an amino acid that determines the properties and identity of the amino acid.