Question 1

Which of the following is FALSE regarding peptide chain termination?

Accepted Answer

A)  RF-1 recognizes the stop codons UAA and UAG 
B)  RF-3-GTP, along with either RF-1 or RF-2, binds to the P-site of the ribosome 
C)  RRF expels the uncharged tRNA from the P-site 
D)  a glutamine residue in RF-1 and RF-2 positions a water molecule to hydrolyze the peptide from the P-site tRNA 
E)  none of the above 
A)  RF-1 recognizes the stop codons UAA and UAG 
B)  RF-3-GTP, along with either RF-1 or RF-2, binds to the P-site of the ribosome 
C)  RRF expels the uncharged tRNA from the P-site 
D)  a glutamine residue in RF-1 and RF-2 positions a water molecule to hydrolyze the peptide from the P-site tRNA 
E)  none of the above

Question 2

Codons representing the same amino acid or chemically similar amino acids tend to be similar in sequence, often differing only in the third base. This feature is called:

Accepted Answer

A)  home-base degeneracy. 
B)  first-base similarity. 
C)  second-base type similarity. 
D)  third-base degeneracy. 
E)  all are true. 
A)  home-base degeneracy. 
B)  first-base similarity. 
C)  second-base type similarity. 
D)  third-base degeneracy. 
E)  all are true.

Question 3

The linkage between the amino acid and the tRNA in an amino-acyl tRNA complex is:

Accepted Answer

A)  an amide 
B)  an acyl phosphate 
C)  a hydroxylamine 
D)  an ether 
E)  an ester 
A)  an amide 
B)  an acyl phosphate 
C)  a hydroxylamine 
D)  an ether 
E)  an ester

Question 4

All of the statements about the tRNA molecule with the anticodon 5'CAU are correct EXCEPT:

Accepted Answer

A)  It is the anticodon for tRNAfmet. 
B)  The wobble base in the anticodon would be cytosine. 
C)  Its anticodon can theoretically base pair with up to three different codons. 
D)  Its anticodon can base pair to the codon 5'AUG. 
E)  All are correct. 
A)  It is the anticodon for tRNAfmet. 
B)  The wobble base in the anticodon would be cytosine. 
C)  Its anticodon can theoretically base pair with up to three different codons. 
D)  Its anticodon can base pair to the codon 5'AUG. 
E)  All are correct.

Question 5

Amino-acyl-tRNA synthetases catalyze the reaction of a:

Accepted Answer

A)  specific amino acid attachment to the 3'-OH at the 3'-CCA of a specific tRNA. 
B)  specific amino acid attachment to the 5'-OH at the 5'-CCA of a specific tRNA. 
C)  specific tRNA with ATP to form a so called "charged tRNA" that interacts with a specific site on mRNA. 
D)  all of the above. 
E)  none of the above. 
A)  specific amino acid attachment to the 3'-OH at the 3'-CCA of a specific tRNA. 
B)  specific amino acid attachment to the 5'-OH at the 5'-CCA of a specific tRNA. 
C)  specific tRNA with ATP to form a so called "charged tRNA" that interacts with a specific site on mRNA. 
D)  all of the above. 
E)  none of the above.

Question 6

____ converts the language of genetic information embodied in the base sequence of a mRNA molecule into the amino acid sequence of a polypeptide chain.

Accepted Answer

A)  Replication 
B)  Translation 
C)  Transcription 
D)  Degradation 
E)  Translocation 
A)  Replication 
B)  Translation 
C)  Transcription 
D)  Degradation 
E)  Translocation

Question 7

Which of the following proteins is NOT correctly defined?

Accepted Answer

A)  IF-2: G-protein that binds to the initial f-met tRNA 
B)  EF-Tu: G-protein that binds aminoacyl-tRNA 
C)  EF-Ts: G-protein that promotes translocation of mRNA 
D)  RF-3: G-protein that is a structural mimic of tRNA 
E)  all are true. 
A)  IF-2: G-protein that binds to the initial f-met tRNA 
B)  EF-Tu: G-protein that binds aminoacyl-tRNA 
C)  EF-Ts: G-protein that promotes translocation of mRNA 
D)  RF-3: G-protein that is a structural mimic of tRNA 
E)  all are true.

Question 8

The adapter molecule that interacts specifically with both nucleic acids and amino acids is:

Accepted Answer

A)  rRNA. 
B)  tRNA. 
C)  mRNA. 
D)  ssRNA. 
E)  all are true. 
A)  rRNA. 
B)  tRNA. 
C)  mRNA. 
D)  ssRNA. 
E)  all are true.

Question 9

Discuss the steps involved in peptide chain elongation.​

Accepted Answer

​
Chain elongation can be divided into t

Question 10

Ribosomal proteins are typically rich in the amino acids ____ and ____ to interact with ____ RNAs.

Accepted Answer

A)  asp; glu; polycationic 
B)  asp; ala; polycationic 
C)  lys; ala; polyanionic 
D)  ala; arg; polyanionic 
E)  arg; lys; polyanionic 
A)  asp; glu; polycationic 
B)  asp; ala; polycationic 
C)  lys; ala; polyanionic 
D)  ala; arg; polyanionic 
E)  arg; lys; polyanionic

Question 11

Which of the following is/are true regarding the genetic code?

Accepted Answer

A)  codons are read 5' to 3' 
B)  there are 20 total "sense" codons, one for each amino acid 
C)  there are three nonsense codons; these are "stop" signals 
D)  a and c are true 
E)  a, b, and c are true 
A)  codons are read 5' to 3' 
B)  there are 20 total "sense" codons, one for each amino acid 
C)  there are three nonsense codons; these are "stop" signals 
D)  a and c are true 
E)  a, b, and c are true

Question 12

The termination signal complex transforms the ribosomal peptidyl transferase into a/an:

Accepted Answer

A)  lyase. 
B)  isomerase. 
C)  hydrolase. 
D)  transferase. 
E)  ligase. 
A)  lyase. 
B)  isomerase. 
C)  hydrolase. 
D)  transferase. 
E)  ligase.

Question 13

Which of the following correctly describes the order of events in the class I aminoacyl-tRNA synthetase reaction?
I. displacement of AMP
II. transesterification
III. nucleophilic attack by 2′-hydroxyl of the tRNA on the acyl adenylate
IV. formation of acyl adenylate by reaction of amino acid with ATP
V. displacement and subsequent hydrolysis of pyrophosphate

Accepted Answer

A)  III, I, IV, V, II 
B)  III, V, IV, I, II 
C)  IV, II, I, III, V 
D)  IV, V, III, I, II 
E)  IV, I, III, II, V 
A)  III, I, IV, V, II 
B)  III, V, IV, I, II 
C)  IV, II, I, III, V 
D)  IV, V, III, I, II 
E)  IV, I, III, II, V

Question 14

An important difference between a class I and class II aminoacyl-tRNA synthetase is:

Accepted Answer

A)  The two classes proceed through different aminoacyl-AMP intermediates. 
B)  Class I synthetases first attach the amino acid to the 2'-hydroxyl on ribose, whereas class II attach them to the 3'-hydroxyl. 
C)  Class I synthetases attach amino acids to the 5'-end of the tRNA, whereas class II attach them to the 3'-end. 
D)  The 5'-end of the tRNA molecule is phosphorylated only for those tRNAs recognized by class I synthetases. 
E)  None are true. 
A)  The two classes proceed through different aminoacyl-AMP intermediates. 
B)  Class I synthetases first attach the amino acid to the 2'-hydroxyl on ribose, whereas class II attach them to the 3'-hydroxyl. 
C)  Class I synthetases attach amino acids to the 5'-end of the tRNA, whereas class II attach them to the 3'-end. 
D)  The 5'-end of the tRNA molecule is phosphorylated only for those tRNAs recognized by class I synthetases. 
E)  None are true.

Question 15

Peptidyl transferase is the catalytic center of the ribosome and is located:

Accepted Answer

A)  on the 30 S subunit near the decoding center. 
B)  on the 30 S subunit near the head. 
C)  on the 50 S subunit near the center protuberance. 
D)  on the 50 S subunit at the bottom of a deep cleft. 
E)  on the 50 S subunit at the cleft of the L7/L12 ridge. 
A)  on the 30 S subunit near the decoding center. 
B)  on the 30 S subunit near the head. 
C)  on the 50 S subunit near the center protuberance. 
D)  on the 50 S subunit at the bottom of a deep cleft. 
E)  on the 50 S subunit at the cleft of the L7/L12 ridge.

Question 16

Nonsense suppression is the production of isoacceptor tRNAs called ____ tRNAs that read ____ codons and insert an amino acid.

Accepted Answer

A)  nonsense; nonsense 
B)  suppressor; nonsense 
C)  suppressor; suppressive 
D)  nonsense; suppressive 
E)  codon; anticodon 
A)  nonsense; nonsense 
B)  suppressor; nonsense 
C)  suppressor; suppressive 
D)  nonsense; suppressive 
E)  codon; anticodon

Question 17

IF-3 is important in the initiation of translation in prokaryotic cells in all EXCEPT:

Accepted Answer

A)  It binds to the 30 S subunit and is required for the binding of the mRNA to this subunit. 
B)  Its association with the 30 S subunit prevents association with the 50 S subunit. 
C)  Its dissociation from the 30 S subunit permits formation of the initiation complex for translation. 
D)  It binds the 70 S subunit to promote binding of a new mRNA. 
E)  All are important. 
A)  It binds to the 30 S subunit and is required for the binding of the mRNA to this subunit. 
B)  Its association with the 30 S subunit prevents association with the 50 S subunit. 
C)  Its dissociation from the 30 S subunit permits formation of the initiation complex for translation. 
D)  It binds the 70 S subunit to promote binding of a new mRNA. 
E)  All are important.

Question 18

All are characteristics of ribosomal subunit assembly under appropriate conditions of pH and ionic strength EXCEPT:

Accepted Answer

A)  ribosomes self-assemble spontaneously 
B)  no intervention by any additional factors or chaperones is required 
C)  ribosomal proteins bind in a specific order. 
D)  rRNA acts as a scaffold upon which various ribosomal proteins convene 
E)  all are true 
A)  ribosomes self-assemble spontaneously 
B)  no intervention by any additional factors or chaperones is required 
C)  ribosomal proteins bind in a specific order. 
D)  rRNA acts as a scaffold upon which various ribosomal proteins convene 
E)  all are true

Exam 30: Protein Synthesis

Which of the following is FALSE regarding peptide chain termination?

Codons representing the same amino acid or chemically similar amino acids tend to be similar in sequence, often differing only in the third base. This feature is called:

The linkage between the amino acid and the tRNA in an amino-acyl tRNA complex is:

All of the statements about the tRNA molecule with the anticodon 5'CAU are correct EXCEPT:

Amino-acyl-tRNA synthetases catalyze the reaction of a:

____ converts the language of genetic information embodied in the base sequence of a mRNA molecule into the amino acid sequence of a polypeptide chain.

Which of the following proteins is NOT correctly defined?

The adapter molecule that interacts specifically with both nucleic acids and amino acids is:

Discuss the steps involved in peptide chain elongation.​

Ribosomal proteins are typically rich in the amino acids ____ and ____ to interact with ____ RNAs.

Which of the following is/are true regarding the genetic code?

The termination signal complex transforms the ribosomal peptidyl transferase into a/an:

An important difference between a class I and class II aminoacyl-tRNA synthetase is:

Peptidyl transferase is the catalytic center of the ribosome and is located:

Nonsense suppression is the production of isoacceptor tRNAs called ____ tRNAs that read ____ codons and insert an amino acid.

IF-3 is important in the initiation of translation in prokaryotic cells in all EXCEPT:

All are characteristics of ribosomal subunit assembly under appropriate conditions of pH and ionic strength EXCEPT:

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

Discuss the steps involved in peptide chain elongation.

Ribosomal proteins are typically rich in the amino acids and to interact with RNAs.

Nonsense suppression is the production of isoacceptor tRNAs called tRNAs that read codons and insert an amino acid.