Question 1

The anticodon of a tRNA is 5'UUG. What codon(s) can be theoretically recognized by this tRNA?

Accepted Answer

A)  5'CAA only 
B)  5'CAA & 5'CAG 
C)  5'AAC only 
D)  5'AAC & 5' GAC 
E)  5'CAC only 
A)  5'CAA only 
B)  5'CAA & 5'CAG 
C)  5'AAC only 
D)  5'AAC & 5' GAC 
E)  5'CAC only

Question 2

The appropriate order for the basic steps of protein synthesis are:
A.The elongation reaction transfers the peptide chain from the peptidyl-tRNA in the P site to the aminoacyl-tRNA in the A sitE.
B.The P site is occupied by peptidyl-tRNA carrying the growing polypeptide chain.
C.Binding of mRNA by the small subunit followed by association of a particular initiator aminoacyl-tRNA that recognizes the first codon.
D.The large ribosomal subunit joins the initiation complex, preparing it for the elongation stagE.E.The new, longer peptidyl-tRNA moves from the A site into the P site as the ribosome moves one codon further along the mRNA.

Accepted Answer

A)  A, C, E, B, D 
B)  B, E, C, D, A 
C)  C, D, A, B, E 
D)  D, C, E, B, A 
E)  C, D, B, A, E 
A)  A, C, E, B, D 
B)  B, E, C, D, A 
C)  C, D, A, B, E 
D)  D, C, E, B, A 
E)  C, D, B, A, E

Question 3

The energy expenditure for protein synthesis is at least ____ high-energy phosphoric anhydride bonds per amino acid.

Accepted Answer

A)  0 
B)  1 
C)  2 
D)  3 
E)  4 
A)  0 
B)  1 
C)  2 
D)  3 
E)  4

Question 4

A dominant mechanism for control of eukaryotic peptide chain initiation is:

Accepted Answer

A)  allosteric regulation. 
B)  cofactor availability control. 
C)  competitive inhibition. 
D)  phosphorylation/dephosphorylation. 
E)  ribosylation. 
A)  allosteric regulation. 
B)  cofactor availability control. 
C)  competitive inhibition. 
D)  phosphorylation/dephosphorylation. 
E)  ribosylation.

Question 5

Ribosome:mRNA:P-site tRNA complex, with the help of ____, is disassembled by ____ which is an excellent molecular mimic of a(n) ____.

Accepted Answer

A)  ATP; tRNA terminator; GTP 
B)  tRNA; ribosome recycling factor; mRNA 
C)  EF-G; ribosome recycling factor; tRNA 
D)  mRNA; elongation factor; EF-G 
E)  none are true 
A)  ATP; tRNA terminator; GTP 
B)  tRNA; ribosome recycling factor; mRNA 
C)  EF-G; ribosome recycling factor; tRNA 
D)  mRNA; elongation factor; EF-G 
E)  none are true

Question 6

The genetic code is said to be degenerate, which means that:

Accepted Answer

A)  Each codon codes for more than one amino acid. 
B)  An anticodon can interact with more than one codon in the mRNA in which the codon may differ in any or all of the three nucleotides. 
C)  Most amino acids are coded for by more than one codon. 
D)  The code is universally used by virtually all species. 
E)  None are true. 
A)  Each codon codes for more than one amino acid. 
B)  An anticodon can interact with more than one codon in the mRNA in which the codon may differ in any or all of the three nucleotides. 
C)  Most amino acids are coded for by more than one codon. 
D)  The code is universally used by virtually all species. 
E)  None are true.

Question 7

All members of a set of tRNAs specific for a particular amino acid - termed ____ tRNA - are served by one ____.

Accepted Answer

A)  companion; codon family 
B)  companion; tRNA binding site 
C)  isoacid; tRNA family 
D)  isoacceptor; aminoacyl tRNA synthetase 
E)  none are true 
A)  companion; codon family 
B)  companion; tRNA binding site 
C)  isoacid; tRNA family 
D)  isoacceptor; aminoacyl tRNA synthetase 
E)  none are true

Question 8

"Stop" or nonsense codons are recognized by ____ through specific ____ sequences that serve an equivalent of the ____ loop.

Accepted Answer

A)  tRNA; nucleotide; anticodon 
B)  nucleotides; complementary; anticodon 
C)  release factors; nucleotide; codon 
D)  release factors; tripeptide; tRNA anticodon 
E)  tRNA; tripeptide; tRNA anticodon 
A)  tRNA; nucleotide; anticodon 
B)  nucleotides; complementary; anticodon 
C)  release factors; nucleotide; codon 
D)  release factors; tripeptide; tRNA anticodon 
E)  tRNA; tripeptide; tRNA anticodon

Question 9

Protein synthesis in bacterial cells usually starts with a:

Accepted Answer

A)  methionine residue. 
B)  formylmethionine residue. 
C)  cysteine residue. 
D)  valine residue. 
E)  phenylalanine residue. 
A)  methionine residue. 
B)  formylmethionine residue. 
C)  cysteine residue. 
D)  valine residue. 
E)  phenylalanine residue.

Question 10

Discuss the two distinct classes of aminoacyl-tRNA synthetases.​

Accepted Answer

​The aminoacyl-tRNA synthetases fall int

Question 11

Which of the following serves as a guanine-nucleotide exchange factor during the elongation cycle?

Accepted Answer

A)  EF-Tu 
B)  EF-Ts 
C)  EF-G 
D)  EF-NEF 
E)  none of the above 
A)  EF-Tu 
B)  EF-Ts 
C)  EF-G 
D)  EF-NEF 
E)  none of the above

Question 12

Explain the Wobble hypothesis.​

Accepted Answer

Francis Crick hypothesized that the firs

Question 13

Which of the following statements is true regarding ribosomes?

Accepted Answer

A)  they are found in the cytosol and nucleus of all cells 
B)  prokaryotic ribosomes consist of a 30S and a 50S subunit while eukaryotic ribosomes consist of a 60S and an 80S subunit 
C)  ribosomes consist of both protein and ribonucleic acid with the majority of the mass from the protein component 
D)  since the peptidyl transferase activity is perfomed by RNA, it can be considered a ribozyme 
E)  all are true 
A)  they are found in the cytosol and nucleus of all cells 
B)  prokaryotic ribosomes consist of a 30S and a 50S subunit while eukaryotic ribosomes consist of a 60S and an 80S subunit 
C)  ribosomes consist of both protein and ribonucleic acid with the majority of the mass from the protein component 
D)  since the peptidyl transferase activity is perfomed by RNA, it can be considered a ribozyme 
E)  all are true

Question 14

A protein synthesis inhibitor that catalytically inactivates 28S rRNA and is very toxic in eukaryotic cells is:

Accepted Answer

A)  ricin. 
B)  puromycin. 
C)  cycloheximide. 
D)  streptomycin. 
E)  tetracycline. 
A)  ricin. 
B)  puromycin. 
C)  cycloheximide. 
D)  streptomycin. 
E)  tetracycline.

Question 15

In a class I aminoacyl-tRNA synthetase, which of the following reacts with the acyl phosphate formed during the reaction of ATP with the amino acid?

Accepted Answer

A)  5′-hydroxyl of the nucleotide on the 5′ end of the tRNA molecule 
B)  3′-hydroxyl of the nucleotide on the 5′ end of the tRNA molecule 
C)  2′-hydroxyl of the nucleotide on the 5′ end of the tRNA molecule 
D)  3′-hydroxyl of the nucleotide on the 3′ end of the tRNA molecule 
E)  2′-hydroxyl of the nucleotide on the 3′ end of the tRNA molecule 
A)  5′-hydroxyl of the nucleotide on the 5′ end of the tRNA molecule 
B)  3′-hydroxyl of the nucleotide on the 5′ end of the tRNA molecule 
C)  2′-hydroxyl of the nucleotide on the 5′ end of the tRNA molecule 
D)  3′-hydroxyl of the nucleotide on the 3′ end of the tRNA molecule 
E)  2′-hydroxyl of the nucleotide on the 3′ end of the tRNA molecule

Question 16

Each of the following statements regarding ways in which eukaryotic protein synthesis differs from prokaryotic protein synthesis is true EXCEPT:

Accepted Answer

A)  prokaryote protein synthesis is initiated by f-Met, while eukaryotic is initiated by Met 
B)  prokaryotes use a 30S small ribosomal subunit, while eukaryotes use a 40S small ribosomal subunit 
C)  prokaryotic and eukaryotic translation initiation differ significantly in mechanism and process 
D)  prokaryotic termination involves three release factors, while eukaryotic termination involves one 
E)  all of the above are true statements 
A)  prokaryote protein synthesis is initiated by f-Met, while eukaryotic is initiated by Met 
B)  prokaryotes use a 30S small ribosomal subunit, while eukaryotes use a 40S small ribosomal subunit 
C)  prokaryotic and eukaryotic translation initiation differ significantly in mechanism and process 
D)  prokaryotic termination involves three release factors, while eukaryotic termination involves one 
E)  all of the above are true statements

Question 17

Diphtheria toxin is extremely potent and only a few micrograms causes death because it:

Accepted Answer

A)  inhibits f-Met-tRNAimet binding. 
B)  is an enzyme and can catalytically modify a number of GTP-dependent enzymes. 
C)  inhibits translocation of peptidyl-tRNA. 
D)  catalyzes inactivation of 28 S tRNA. 
E)  inhibits EF-G:GTP dissociation from ribosomes. 
A)  inhibits f-Met-tRNAimet binding. 
B)  is an enzyme and can catalytically modify a number of GTP-dependent enzymes. 
C)  inhibits translocation of peptidyl-tRNA. 
D)  catalyzes inactivation of 28 S tRNA. 
E)  inhibits EF-G:GTP dissociation from ribosomes.

Question 18

Elongation factor Tu (EF-Tu):

Accepted Answer

A)  binds GTP promoting translocation of ribosomes along mRNA. 
B)  displaces GDP from the elongation complex. 
C)  binds aminoacyl-tRNA in the presence of GTP. 
D)  binds initiator tRNA and GTP. 
E)  binds to 30 S subunit and drives mRNA binding. 
A)  binds GTP promoting translocation of ribosomes along mRNA. 
B)  displaces GDP from the elongation complex. 
C)  binds aminoacyl-tRNA in the presence of GTP. 
D)  binds initiator tRNA and GTP. 
E)  binds to 30 S subunit and drives mRNA binding.

Question 19

The order of events in the initiation of protein synthesis is:
A.GTP hydrolysis triggered by the 50 S subunit joining the 30 S subunit releasing IF-1, IF-2 and IF-3.
B.IF-2 delivers the initiator f-Met-tRNA ifMet in a GTP-dependent process.
C.A-site of the 70 S initiation complex is ready to accept an incoming aminoacyl-tRNA.
D.IF-3 and IF-1 bind 30 S subunit.
E.mRNA binds to form the 30 S initiation complex.

Accepted Answer

A)  C, A, E, B, D 
B)  E, D, A, B, C 
C)  B, D, C, E, A 
D)  D, B, E, A, C 
E)  D, E, A, B, C 
A)  C, A, E, B, D 
B)  E, D, A, B, C 
C)  B, D, C, E, A 
D)  D, B, E, A, C 
E)  D, E, A, B, C

Question 20

Which inhibitor of protein synthesis competes with aminoacyl-tRNAs for binding to the A-site of the ribosome?

Accepted Answer

A)  puromycin 
B)  erythromycin 
C)  streptomycin 
D)  cycloheximide 
E)  tetracycline 
A)  puromycin 
B)  erythromycin 
C)  streptomycin 
D)  cycloheximide 
E)  tetracycline

Exam 30: Protein Synthesis

The anticodon of a tRNA is 5'UUG. What codon(s) can be theoretically recognized by this tRNA?

The energy expenditure for protein synthesis is at least ____ high-energy phosphoric anhydride bonds per amino acid.

A dominant mechanism for control of eukaryotic peptide chain initiation is:

Ribosome:mRNA:P-site tRNA complex, with the help of ____, is disassembled by ____ which is an excellent molecular mimic of a(n) ____.

The genetic code is said to be degenerate, which means that:

All members of a set of tRNAs specific for a particular amino acid - termed ____ tRNA - are served by one ____.

"Stop" or nonsense codons are recognized by ____ through specific ____ sequences that serve an equivalent of the ____ loop.

Protein synthesis in bacterial cells usually starts with a:

Discuss the two distinct classes of aminoacyl-tRNA synthetases.​

Which of the following serves as a guanine-nucleotide exchange factor during the elongation cycle?

Explain the Wobble hypothesis.​

Which of the following statements is true regarding ribosomes?

A protein synthesis inhibitor that catalytically inactivates 28S rRNA and is very toxic in eukaryotic cells is:

In a class I aminoacyl-tRNA synthetase, which of the following reacts with the acyl phosphate formed during the reaction of ATP with the amino acid?

Each of the following statements regarding ways in which eukaryotic protein synthesis differs from prokaryotic protein synthesis is true EXCEPT:

Diphtheria toxin is extremely potent and only a few micrograms causes death because it:

Elongation factor Tu (EF-Tu):

Which inhibitor of protein synthesis competes with aminoacyl-tRNAs for binding to the A-site of the ribosome?

The Facts of Life: Chemistry Is the Logic of Biological Phenomena

Water: the Medium of Life

Thermodynamics of Biological Systems

Amino Acids and the Peptide Bond

Proteins: Their Primary Structure and Biological Functions

Proteins: Secondary, Tertiary, and Quaternary Structure

Carbohydrates and the Glycoconjugates of Cell Surfaces

Lipids

Membranes and Membrane Transport

Nucleotides and Nucleic Acids

Structure of Nucleic Acids

Recombinant Dna, Cloning, Chimeric Genes, and Synthetic Biology

Enzymeskinetics and Specificity

Mechanisms of Enzyme Action

Enzyme Regulation

Molecular Motors

Metabolism: an Overview

Glycolysis

The Tricarboxylic Acid Cycle

Electron Transport and Oxidative Phosphorylation

Photosynthesis

Gluconeogenesis, Glycogen Metabolism, and the Pentose Phosphate Pathway

Fatty Acid Catabolism

Lipid Biosynthesis

Nitrogen Acquisition and Amino Acid Metabolism

Synthesis and Degradation of Nucleotides

Metabolic Integration and Organ Specialization

Dna Metabolism: Replication, Recombination, and Repair

Transcription and the Regulation of Gene Expression

Completing the Protein Life Cycle: Folding, Processing, and Degradation

The Reception and Transmission of Extracellular Information

Filters

Ribosome:mRNA:P-site tRNA complex, with the help of , is disassembled by which is an excellent molecular mimic of a(n) .

All members of a set of tRNAs specific for a particular amino acid - termed tRNA - are served by one .

"Stop" or nonsense codons are recognized by through specific sequences that serve an equivalent of the loop.

Discuss the two distinct classes of aminoacyl-tRNA synthetases.

Explain the Wobble hypothesis.