Question 1

What is the adapter molecule that interacts specifically with both nucleic acids and amino acids?

Accepted Answer

A) rRNA 
B) tRNA 
C) mRNA 
D) ssRNA 
A) rRNA 
B) tRNA 
C) mRNA 
D) ssRNA B

Question 2

Which of the following is NOT classified as a GTP-binding protein?

Accepted Answer

A) 30S rRNA 
B) EF-Tu 
C) EF-G 
D) RF-3 
A) 30S rRNA 
B) EF-Tu 
C) EF-G 
D) RF-3 A

Question 3

Which of the following can be considered active with respect to the initiation of protein synthesis?

Accepted Answer

A) intact 70S 
B) free 50S 
C) free 30S 
D) mRNA-bound 30S 
A) intact 70S 
B) free 50S 
C) free 30S 
D) mRNA-bound 30S C

Question 4

Which of the following processes does NOT require GTP hydrolysis?

Accepted Answer

A) the formation of the initiation complex (translationally active,70S ribosome complex) 
B) the elongation step of translation 
C) the translocation step of translation 
D) the binding of release factors to the ribosome 
A) the formation of the initiation complex (translationally active,70S ribosome complex) 
B) the elongation step of translation 
C) the translocation step of translation 
D) the binding of release factors to the ribosome

Question 5

Which of the following is a feature of isoacceptor tRNAs called suppressors?

Accepted Answer

A) They read suppressive codons and insert an amino acid. 
B) They read nonsense codons and insert an amino acid. 
C) They read anticodon codons and insert an amino acid. 
D) They read mutated codons and insert an amino acid. 
A) They read suppressive codons and insert an amino acid. 
B) They read nonsense codons and insert an amino acid. 
C) They read anticodon codons and insert an amino acid. 
D) They read mutated codons and insert an amino acid.

Question 6

Which nucleotide and its hydrolysis provide the driving energy for protein biosynthesis in all cells?

Accepted Answer

A) ATP 
B) GTP 
C) UTP 
D) CTP 
A) ATP 
B) GTP 
C) UTP 
D) CTP

Question 7

The ribosome:mRNA:P-site tRNA complex,with the help of EF-G,is disassembled by ribosome recycling factor.Which of the following is the ribosome recycling factor an excellent molecular mimic of?

Accepted Answer

A) GTP 
B) mRNA 
C) tRNA 
D) EF-G 
A) GTP 
B) mRNA 
C) tRNA 
D) EF-G

Question 8

Which of the following is NOT a characteristic of ribosomes?

Accepted Answer

A) They are found in the endoplasmic reticulum of all cells. 
B) Prokaryotic ribosomes consist of a 30S and a 50S subunit. 
C) Ribosomes consist of both protein and ribonucleic acid. 
D) The catalytic centre of the large subunit is a peptidyl transferase. 
A) They are found in the endoplasmic reticulum of all cells. 
B) Prokaryotic ribosomes consist of a 30S and a 50S subunit. 
C) Ribosomes consist of both protein and ribonucleic acid. 
D) The catalytic centre of the large subunit is a peptidyl transferase.

Question 9

The central domain of the 30S ribosomal subunit serves as the decoding centre.What is it composed of?

Accepted Answer

A) 5S rRNA 
B) 16S rRNA 
C) 23S rRNA 
D) 50S rRNA 
A) 5S rRNA 
B) 16S rRNA 
C) 23S rRNA 
D) 50S rRNA

Question 10

What type of ribosomes do mitochondrial and chloroplastic ribosomes resemble?

Accepted Answer

A) prokaryotic 
B) lower eukaryotic 
C) higher eukaryotic 
D) viral 
A) prokaryotic 
B) lower eukaryotic 
C) higher eukaryotic 
D) viral

Question 11

Which of the following is an important difference between a class I and a class II aminoacyl-tRNA synthetase?

Accepted Answer

A) The 2 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. 
A) The 2 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.

Question 12

Which of these reactions do amino-acyl-tRNA synthetases catalyze?

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) specific tRNA with GTP to form a so-called "charged tRNA" that interacts with a specific site on mRNA 
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) specific tRNA with GTP to form a so-called "charged tRNA" that interacts with a specific site on mRNA

Question 13

Which of the following is NOT involved in the initiation of protein synthesis?

Accepted Answer

A) GTP hydrolysis is triggered by the 50S subunit joining the 30S subunit,releasing IF-1,IF-2,and IF-3. 
B) IF-2 delivers the initiator f-Met-tRNAifMet in a GTP-dependent process. 
C) A-site of the 70S initiation complex is ready to accept an incoming aminoacyl-tRNA. 
D) IF-2 and IF-3 bind the 30S subunit. 
A) GTP hydrolysis is triggered by the 50S subunit joining the 30S subunit,releasing IF-1,IF-2,and IF-3. 
B) IF-2 delivers the initiator f-Met-tRNAifMet in a GTP-dependent process. 
C) A-site of the 70S initiation complex is ready to accept an incoming aminoacyl-tRNA. 
D) IF-2 and IF-3 bind the 30S subunit.

Question 14

Which of the following is NOT a characteristic of the genetic code?

Accepted Answer

A) It is degenerate. 
B) It is read 3' to 5'. 
C) It is read from a fixed starting point without punctuation. 
D) It is not overlapping. 
A) It is degenerate. 
B) It is read 3' to 5'. 
C) It is read from a fixed starting point without punctuation. 
D) It is not overlapping.

Question 15

Which of the following is a protein synthesis inhibitor that catalytically inactivates 28S rRNA and is very toxic in eukaryotic cells?

Accepted Answer

A) ricin 
B) puromycin 
C) cycloheximide 
D) tetracycline 
A) ricin 
B) puromycin 
C) cycloheximide 
D) tetracycline

Question 16

Approximately how much of the dry cell mass of an E.coli cell consists of ribosomes?

Accepted Answer

A) 1% 
B) 5% 
C) 10% 
D) 20% 
A) 1% 
B) 5% 
C) 10% 
D) 20%

Question 17

Diphtheria toxin is extremely potent and only a few micrograms cause death.What is its mechanism of action?

Accepted Answer

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

Question 18

Peptidyl transferase is the catalytic centre of the ribosome.Where is it located?

Accepted Answer

A) on the 30 S subunit near the decoding centre 
B) on the 30 S subunit near the head 
C) on the 50 S subunit near the centre protuberance 
D) on the 50 S subunit at the bottom of a deep cleft 
A) on the 30 S subunit near the decoding centre 
B) on the 30 S subunit near the head 
C) on the 50 S subunit near the centre protuberance 
D) on the 50 S subunit at the bottom of a deep cleft

Question 19

Which of the following is NOT a role for IF-3 during the initiation of translation in prokaryotic cells?

Accepted Answer

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

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

Exam 30: Protein Synthesis

What is the adapter molecule that interacts specifically with both nucleic acids and amino acids?

Which of the following is NOT classified as a GTP-binding protein?

Which of the following can be considered active with respect to the initiation of protein synthesis?

Which of the following processes does NOT require GTP hydrolysis?

Which of the following is a feature of isoacceptor tRNAs called suppressors?

Which nucleotide and its hydrolysis provide the driving energy for protein biosynthesis in all cells?

The ribosome:mRNA:P-site tRNA complex,with the help of EF-G,is disassembled by ribosome recycling factor.Which of the following is the ribosome recycling factor an excellent molecular mimic of?

Which of the following is NOT a characteristic of ribosomes?

The central domain of the 30S ribosomal subunit serves as the decoding centre.What is it composed of?

What type of ribosomes do mitochondrial and chloroplastic ribosomes resemble?

Which of the following is an important difference between a class I and a class II aminoacyl-tRNA synthetase?

Which of these reactions do amino-acyl-tRNA synthetases catalyze?

Which of the following is NOT involved in the initiation of protein synthesis?

Which of the following is NOT a characteristic of the genetic code?

Which of the following is a protein synthesis inhibitor that catalytically inactivates 28S rRNA and is very toxic in eukaryotic cells?

Approximately how much of the dry cell mass of an E.coli cell consists of ribosomes?

Diphtheria toxin is extremely potent and only a few micrograms cause death.What is its mechanism of action?

Peptidyl transferase is the catalytic centre of the ribosome.Where is it located?

Which of the following is NOT a role for IF-3 during the initiation of translation in prokaryotic cells?

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

Proteins: Their Primary Structure and Biological Functions

Proteins: Secondary, tertiary, and Quaternary Structure

Carbohydrates and the Glycoconjugates of Cell Surfaces

Lipids

Lipid Biosynthesis

Membranes and Membrane Transport

The Reception and Transmission of Extracellular Information

Enzymes Kinetics and Specificity

Mechanisms of Enzyme Action

Enzyme Regulation

Molecular Motors

Nutrition and the Organization of Metabolism

Glycolysis

The Tricarboxylic Acid Cycle

Electron Transport and Oxidative Phosphorylation

Photosynthesis

Gluconeogenesis, glycogen Metabolism, and the Pentose Phosphate Pathway

Fatty Acid Catabolism

Nitrogen Acquisition and Amino Acid Metabolism

Nucleotides and Nucleic Acids

Structure of Nucleic Acids

Synthesis and Degradation of Nucleotides

Recombinant Dna: Cloning and Creation of Chimeric Genes

DNA Metabolism: Replication, recombination, and Repair

Transcription and the Regulation of Gene Expression

Post-Transcriptional Regulation of Gene Expression

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

Metabolic Integration and Organ Specialization

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