Q4 Biochem Practice Set

Which component of the prokaryotic ribosome contains the catalytic activity for peptide bond formation? A) Ribosomal proteins B) 30S subunit C) Ribosomal RNA (rRNA) D) Transfer RNA (tRNA)

C) Ribosomal RNA (rRNA)

What is the directionality of protein synthesis? A) C-terminus to N-terminus B) N-terminus to C-terminus C) 5' to 3' D) 3' to 5'

B) N-terminus to C-terminus

In prokaryotes, what is the initial N-terminal amino acid? A) Methionine B) N-formylmethionine C) Glycine D) Serine

B) N-formylmethionine

Which mRNA sequence directs the prokaryotic ribosome to the start site? A) TATA box B) Pribnow box C) Shine-Dalgarno sequence D) Poly-A tail

C) Shine-Dalgarno sequence

Which site on the ribosome is the site of catalysis where a new peptide bond is formed? A) A-site B) P-site C) E-site D) T-site

B) P-site

What chemical mechanism forms the new peptide bond during translation? A) Nucleophilic attack of the alpha-amino group B) Electrophilic addition C) Hydrolysis of the ester bond D) Phosphorylation

A) Nucleophilic attack of the alpha-amino group

Eukaryotic mRNAs are characterized by which of the following modifications? A) 3' GTP cap and 5' poly-A tail B) 5' 7-methyl GTP cap and 3' poly-A tail C) Shine-Dalgarno sequence D) Removal of the poly-A tail

B) 5' 7-methyl GTP cap and 3' poly-A tail

In the ubiquitin-proteasome pathway, which enzyme is the ligating enzyme that transfers ubiquitin to the substrate protein? A) E1 B) E2 C) E3 D) Protease

C) E3

According to the N-terminal degron rule, which of the following N-terminal amino acids gives a protein a very short half-life? A) Methionine (M) B) Serine (S) C) Alanine (A) D) Arginine (R)

D) Arginine (R)

In the modified standard state for biochemical reactions (delta G naught prime), what is the assumed pH? A) 0 B) 7 C) 14 D) 7.4

B) 7

Anabolism is broadly defined as processes that: A) Break down biomolecules and release energy B) Break down biomolecules and require energy C) Build biomolecules and release energy D) Build biomolecules and require energy

D) Build biomolecules and require energy

Which of the following makes ATP hydrolysis thermodynamically favorable? A) Increase in electrostatic repulsion B) Decrease in resonance stabilization C) Decrease in electrostatic repulsion D) Decrease in entropy

C) Decrease in electrostatic repulsion

What is the net yield of ATP from the glycolysis of one molecule of glucose? A) 1 ATP B) 2 ATP C) 3 ATP D) 4 ATP

B) 2 ATP

Which of the following is NOT a regulatory control point in glycolysis? A) Hexokinase B) Phosphofructokinase C) Aldolase D) Pyruvate kinase

C) Aldolase

Phosphofructokinase (PFK) is allosterically inhibited by high cellular concentrations of: A) AMP B) ATP C) Fructose-6-phosphate D) Glucose

B) ATP

Which enzyme in glycolysis utilizes inorganic phosphate (Pi) instead of ATP to phosphorylate its substrate? A) Hexokinase B) Phosphofructokinase C) Glyceraldehyde-3-phosphate dehydrogenase D) Pyruvate kinase

C) Glyceraldehyde-3-phosphate dehydrogenase

The generation of ATP by phosphoglycerate kinase and pyruvate kinase is an example of: A) Oxidative phosphorylation B) Substrate-level phosphorylation C) Photophosphorylation D) Oxidative decarboxylation

B) Substrate-level phosphorylation

Under anaerobic conditions, what is the fate of pyruvate generated by glycolysis? A) Converted to oxaloacetate B) Converted to Acetyl-CoA C) Converted to lactate D) Converted to glucose

C) Converted to lactate

In gluconeogenesis, which enzyme catalyzes the conversion of pyruvate to oxaloacetate? A) Pyruvate kinase B) Pyruvate carboxylase C) PEP carboxykinase D) Fructose-1,6-bisphosphatase

B) Pyruvate carboxylase

What cofactor is utilized by pyruvate carboxylase to carry and transfer carbon dioxide? A) NAD+ B) FAD C) Biotin D) Thiamine pyrophosphate

C) Biotin

In gluconeogenesis, fructose-1,6-bisphosphatase is strongly allosterically inhibited by: A) ATP B) AMP C) Citrate D) Glucose-6-phosphate

B) AMP

Where in the cell does the final step of gluconeogenesis (catalyzed by glucose-6-phosphatase) occur? A) Cytoplasm B) Mitochondria C) Endoplasmic reticulum D) Lysosome

C) Endoplasmic reticulum

What is the primary purpose of the Pentose Phosphate Pathway (PPP)? A) Generate ATP B) Generate NADPH and ribose-5-phosphate C) Generate pyruvate D) Generate glucose from lactate

B) Generate NADPH and ribose-5-phosphate

In the non-oxidative phase of the PPP, which enzyme catalyzes two-carbon shift reactions? A) Transaldolase B) Transketolase C) Isomerase D) Epimerase

B) Transketolase

In prokaryotes, what term describes the simultaneous transcription of mRNA from DNA and translation of that mRNA into protein? A) Polysome formation B) Coupled translation C) Substrate-level phosphorylation D) Oxidative phosphorylation

B) Coupled translation