Question 1

Chaperone proteins help to fold newly translated proteins into correct configurations.

Accepted Answer

A) True 
 B)False

Question 2

At the ribosome, the codon and anticodon associate by .

Accepted Answer

A)  hydrogen bonding 
B)  disulfide bonds 
C)  ionic attractions 
D)  covalent bonding 
E)  hydrophobic interactions 
A)  hydrogen bonding 
B)  disulfide bonds 
C)  ionic attractions 
D)  covalent bonding 
E)  hydrophobic interactions

Question 3

carries the anticodon.

Accepted Answer

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

Question 4

Which is true about proofreading activity during the synthesis of aminoacyl-tRNAs?

Accepted Answer

A)  Proofreading is accomplished as an amino acid enters the active site of the enzyme. Incorrect amino acids are rejected before any reaction occurs. 
B)  Proofreading occurs just after aminoacyl-adenylate formation. 
C)  A separate cytosolic proofreading enzyme catalyzes the hydrolysis of incorrect aminoacyl-tRNAs. 
D)  No proofreading activity is necessary due to the high level of specificity of all aminoacyl-tRNA synthetases. 
A)  Proofreading is accomplished as an amino acid enters the active site of the enzyme. Incorrect amino acids are rejected before any reaction occurs. 
B)  Proofreading occurs just after aminoacyl-adenylate formation. 
C)  A separate cytosolic proofreading enzyme catalyzes the hydrolysis of incorrect aminoacyl-tRNAs. 
D)  No proofreading activity is necessary due to the high level of specificity of all aminoacyl-tRNA synthetases.

Question 5

Proteins processed through the Golgi apparatus and usually destined for export from the cell are modified by glycosylation only.

Accepted Answer

A) True 
 B)False

Question 6

How many GTP are hydrolyzed for every aminoacyl-tRNA that is successfully inserted into the A site of the ribosome?

Accepted Answer

A)  zero 
B)  1 
C)  2 
D)  4 
A)  zero 
B)  1 
C)  2 
D)  4

Question 7

Different codons that specify the same amino acid are called codons.

Accepted Answer

A)  synonymous 
B)  repetitive 
C)  variable 
D)  multiplex 
A)  synonymous 
B)  repetitive 
C)  variable 
D)  multiplex

Question 8

Chain elongation consists of three steps: 1) positioning the correct aminoacyl-tRNA to the A site, 2) forming the peptide bond and 3) .

Accepted Answer

A)  dissociation of the 30S and 50S subunits 
B)  removal of the fMet-tRNAfmet from the complex 
C)  moving the mRNA along one codon 
D)  All of the above 
E)  None of the above 
A)  dissociation of the 30S and 50S subunits 
B)  removal of the fMet-tRNAfmet from the complex 
C)  moving the mRNA along one codon 
D)  All of the above 
E)  None of the above

Question 9

Tryptophan synthesis can be controlled by a process called attenuation in which the levels of tryptophan in the cell control translation by

Accepted Answer

A)  the binding of the RNA polymerase to the genome. 
B)  the alteration of the repressor protein. 
C)  the folding of mRNA into hairpin loops. 
D)  genes rich in codons for tryptophan. 
A)  the binding of the RNA polymerase to the genome. 
B)  the alteration of the repressor protein. 
C)  the folding of mRNA into hairpin loops. 
D)  genes rich in codons for tryptophan.

Question 10

Inosinate (I) is an acetylated form of G and it can base-pair with A, C, or U.

Accepted Answer

A) True 
 B)False

Question 11

The codon for the amino acid specified by the anticodon at the anticodon arm of tRNA is covalently linked to tRNA at the

Accepted Answer

A)  variable arm. 
B)  D arm. 
C)  TyC arm. 
D)  acceptor arm. 
A)  variable arm. 
B)  D arm. 
C)  TyC arm. 
D)  acceptor arm.

Question 12

The anticodon of tRNAala can bind to three different codons for alanine GCU, GCC and GCA) because

Accepted Answer

A)  there are different bases at the 5ʹ end position of the anticodon. 
B)  there are different bases at the 3ʹ end position of the anticodon. 
C)  the base at the 5ʹ position of the anticodon is I and is the wobble position. 
D)  the base at the 3ʹ position of the anticodon is I and is the wobble position. 
A)  there are different bases at the 5ʹ end position of the anticodon. 
B)  there are different bases at the 3ʹ end position of the anticodon. 
C)  the base at the 5ʹ position of the anticodon is I and is the wobble position. 
D)  the base at the 3ʹ position of the anticodon is I and is the wobble position.

Question 13

Which statement is not true about the ʺwobbleʺ position?

Accepted Answer

A)  It is in the 5ʹ position on the anticodon. 
B)  Base pairing other than Watson-Crick base pairing is allowed at this position. 
C)  It allows anticodons to recognize more than one codon. 
D)  Often has inosinate at the 3ʹ position of the codon. 
A)  It is in the 5ʹ position on the anticodon. 
B)  Base pairing other than Watson-Crick base pairing is allowed at this position. 
C)  It allows anticodons to recognize more than one codon. 
D)  Often has inosinate at the 3ʹ position of the codon.

Question 14

Which help cells avoid mis-insertion of amino acids in protein synthesis?

Accepted Answer

A)  the specificity of codon:anticodon interactions 
B)  the specificity of tRNA: amino acid pairs 
C)  the proofreading ability of tRNA synthetases 
D)  All of the above 
A)  the specificity of codon:anticodon interactions 
B)  the specificity of tRNA: amino acid pairs 
C)  the proofreading ability of tRNA synthetases 
D)  All of the above

Question 15

Which statement is false concerning ribosomes and their components?

Accepted Answer

A)  All ribosomes have two subunits of unequal size. 
B)  The genes for eukaryotic rRNA occur as tandem arrays of hundreds of copies. 
C)  The 30S and 50S ribosomal subunits of E. coli combine to generate an 80S subunit. 
D)  Sequences exist in prokaryotic and eukaryotic rRNA that are so similar, they likely derive from a common ancestor. 
A)  All ribosomes have two subunits of unequal size. 
B)  The genes for eukaryotic rRNA occur as tandem arrays of hundreds of copies. 
C)  The 30S and 50S ribosomal subunits of E. coli combine to generate an 80S subunit. 
D)  Sequences exist in prokaryotic and eukaryotic rRNA that are so similar, they likely derive from a common ancestor.

Question 16

The deaminoacylated tRNA leaves the ribosome as the growing polypeptide passes through the tunnel of the large ribosomal subunit from the .

Accepted Answer

A)  30S or 40S subunit 
B)  protein factors 
C)  E site 
D)  P site 
A)  30S or 40S subunit 
B)  protein factors 
C)  E site 
D)  P site

Question 17

What is the 5ʹ → 3ʹ anticodon for an amino acid with the codon CAG?

Accepted Answer

A)  GAC 
B)  CUG 
C)  GUC 
D)  CTG 
A)  GAC 
B)  CUG 
C)  GUC 
D)  CTG

Question 18

The role of EF-Tu in bacterial protein synthesis is

Accepted Answer

A)  formation of the peptide bond. 
B)  positioning the correct aminoacyl-tRNA at the A site. 
C)  positioning the correct aminoacyl-tRNA at the P site. 
D)  moving the mRNA by one codon. 
E)  All of the above 
A)  formation of the peptide bond. 
B)  positioning the correct aminoacyl-tRNA at the A site. 
C)  positioning the correct aminoacyl-tRNA at the P site. 
D)  moving the mRNA by one codon. 
E)  All of the above

Question 19

Which statement is false concerning aminoacyl-tRNA synthetase?

Accepted Answer

A)  It recognizes only one amino acid, but may recognize more than one tRNA. 
B)  It requires a conversion from ATP to ADP. 
C)  Hydrolysis of pyrophosphate essentially makes its reaction irreversible. 
D)  Some synthetases bind the anticodon and others do not. 
A)  It recognizes only one amino acid, but may recognize more than one tRNA. 
B)  It requires a conversion from ATP to ADP. 
C)  Hydrolysis of pyrophosphate essentially makes its reaction irreversible. 
D)  Some synthetases bind the anticodon and others do not.

Question 20

If there is more globin than heme present in a reticulocyte, globin synthesis is stopped by

Accepted Answer

A)  the activation of HCI heme-controlled inhibitor). 
B)  the inactivation of HCI. 
C)  increasing heme synthesis. 
D)  decreasing heme synthesis. 
E)  activating eIF-2. 
A)  the activation of HCI heme-controlled inhibitor). 
B)  the inactivation of HCI. 
C)  increasing heme synthesis. 
D)  decreasing heme synthesis. 
E)  activating eIF-2.

Exam 22: Protein Synthesis

Chaperone proteins help to fold newly translated proteins into correct configurations.

At the ribosome, the codon and anticodon associate by .

carries the anticodon.

Which is true about proofreading activity during the synthesis of aminoacyl-tRNAs?

Proteins processed through the Golgi apparatus and usually destined for export from the cell are modified by glycosylation only.

How many GTP are hydrolyzed for every aminoacyl-tRNA that is successfully inserted into the A site of the ribosome?

Different codons that specify the same amino acid are called codons.

Chain elongation consists of three steps: 1) positioning the correct aminoacyl-tRNA to the A site, 2) forming the peptide bond and 3) .

Tryptophan synthesis can be controlled by a process called attenuation in which the levels of tryptophan in the cell control translation by

Inosinate (I) is an acetylated form of G and it can base-pair with A, C, or U.

The codon for the amino acid specified by the anticodon at the anticodon arm of tRNA is covalently linked to tRNA at the

The anticodon of tRNAala can bind to three different codons for alanine GCU, GCC and GCA) because

Which statement is not true about the ʺwobbleʺ position?

Which help cells avoid mis-insertion of amino acids in protein synthesis?

Which statement is false concerning ribosomes and their components?

The deaminoacylated tRNA leaves the ribosome as the growing polypeptide passes through the tunnel of the large ribosomal subunit from the .

What is the 5ʹ → 3ʹ anticodon for an amino acid with the codon CAG?

The role of EF-Tu in bacterial protein synthesis is

Which statement is false concerning aminoacyl-tRNA synthetase?

If there is more globin than heme present in a reticulocyte, globin synthesis is stopped by

Introduction to Biochemistry

Water

Amino Acids and the Primary Structures of Proteins

Proteins: Three-Dimensional Structure and Function

Properties of Enzymes

Mechanisms of Enzymes

Coenzymes and Vitamins

Carbohydrates

Lipids and Membranes

Introduction to Metabolism

Glycolysis

Gluconeogenesis, the Pentose Phosphate Pathway, and Glycogen Metabolism

The Citric Acid Cycle

Electron Transport and Oxidative Phosphorylation

Photosynthesis

Lipid Metabolism

Amino Acid Metabolism

Nucleotide Metabolism

Nucleic Acids

Dna Replication, Repair, and Recombination

Transcription and Rna Processing

Recombinant Dna Technology

Filters

The anticodon of tRNA^alacan bind to three different codons for alanine GCU, GCC and GCA) because