Practice Questions

A coenzyme acts as a co-substrate; it binds, accepts a chemical group from one substrate, and transfers it to another, being regenerated in the process.

Cofactors are non-protein components (metal ions or coenzymes) required for the activity of many enzymes, distinguishing simple from conjugated enzymes.

Group specificity means an enzyme acts on a family of structurally related substrates (like alcohols) due to shared functional groups.

A mutation in the small number of residues forming the active site would directly abolish enzyme function, unlike mutations in distant structural or surface regions.

The lock-and-key model proposes that the enzyme's active site (lock) is a rigid, pre-shaped template perfectly complementary to a specific substrate (key).

Once all substrate is consumed, adding more enzyme cannot generate more product, and the reaction rate plateaus due to substrate depletion.

Activation of zymogens requires specific, irreversible proteolytic cleavage to remove a blocking peptide, allowing the protein to fold into its active conformation.

Higher temperatures increase molecular kinetic energy, leading to more frequent and forceful collisions that increase the chance of overcoming the activation energy barrier.

Malonate is a structural analog of succinate and competes for the active site of succinate dehydrogenase, demonstrating competitive inhibition.

Allosteric regulation involves binding to a regulatory site, which induces a conformational change transmitted to the active site, modifying its affinity or efficiency.