MCAT (Biological and Biochemical) 2

Question 1

Which enzyme catalyzes the committed step of glycolysis?

Accepted Answer

Phosphofructokinase-1

Answer

Phosphofructokinase-1 (PFK-1) catalyzes the irreversible conversion of fructose-6-phosphate to fructose-1,6-bisphosphate, which is the committed and rate-limiting step of glycolysis.

Question 2

During oxidative phosphorylation, where do electrons from NADH ultimately transfer?

Accepted Answer

Molecular oxygen

Answer

Electrons from NADH pass through the electron transport chain and are ultimately accepted by molecular oxygen (O2), which is reduced to water (H2O).

Question 3

Which type of RNA carries the genetic code from the nucleus to the ribosome for translation?

Accepted Answer

mRNA

Answer

Messenger RNA (mRNA) carries the genetic information transcribed from DNA and serves as the template for protein synthesis at the ribosome.

Question 4

A mutation that converts a codon from UAU (Tyr) to UAA results in what type of mutation?

Accepted Answer

Nonsense mutation

Answer

UAA is a stop codon; converting an amino acid codon to a stop codon creates a nonsense mutation that causes premature termination of translation.

Question 5

Which bond connects amino acids in a polypeptide chain?

Accepted Answer

Peptide bond

Answer

A peptide bond is a covalent amide bond formed between the carboxyl group of one amino acid and the amino group of the next during translation.

MCAT - Medical College Admission Test Practice Test

MCAT - Medical College Admission Test Practice Test

MCAT (Biological and Biochemical) 2