Test: Chemistry - 9 - MCAT MCQ

Stereoisomers have the same molecular formula and connectivity but differ in the spatial arrangement of atoms. This leads to differences in their physical properties, such as boiling points, melting points, and optical activity.

Chiral molecules are not superimposable on their mirror image and possess a property called optical activity. They rotate the plane of polarized light in a specific direction.

Meso compounds are optically inactive stereoisomers that possess chiral centers but have an internal plane of symmetry. Tartaric acid is an example of a meso compound.

Leucine is an example of a nonpolar amino acid. It has a hydrophobic side chain and is often found in the interior of proteins.

The primary structure of a protein refers to the linear sequence of amino acids held together by peptide bonds. It is the first level of protein structure.

Alpha-helices are formed by intramolecular hydrogen bonding between the carbonyl group of one amino acid and the amino group of another amino acid within the same polypeptide chain.

Collagen is an example of a fibrous protein. It is a structural protein found in connective tissues, providing strength and flexibility.

Van der Waals forces, including London dispersion forces and dipole-dipole interactions, play a significant role in stabilizing the tertiary structure of proteins by maintaining the spatial arrangement of amino acid side chains.

Prosthetic groups are non-protein molecules that are permanently attached to proteins and play a critical role in their function. Zinc is an example of a prosthetic group in carbonic anhydrase, an enzyme involved in carbon dioxide transport.

Denaturation refers to the disruption of a protein's native structure, resulting in the loss of its biological activity. This can be caused by various factors, such as heat, pH changes, and exposure to chemicals or detergents.

Cysteine is the amino acid with a sulfur-containing side chain. It plays a crucial role in the formation of disulfide bonds, contributing to the protein's higher-order structure.

Hemoglobin is an example of a globular protein. Globular proteins have a compact, roughly spherical shape and are typically soluble in water. They often perform dynamic functions in cells.

Aspartic acid has a carboxyl group (COOH) in its side chain, which can ionize and become negatively charged at physiological pH.

Peptide bonds are formed through a condensation reaction known as dehydration synthesis or a dehydration reaction. This involves the removal of a water molecule between the amino group of one amino acid and the carboxyl group of another amino acid.

The alpha-helix is a common secondary structure in proteins, characterized by a right-handed coiled arrangement of the polypeptide chain. Secondary structure is primarily determined by hydrogen bonding between the backbone atoms of the amino acids.