Question 1

In E. coli translation, _____ aids with binding of the fMet-tRNA to the 30S subunit while _____ blocks the A site.

Accepted Answer

A)   IF-1; IF-2
B)   IF-1; IF-3
C)   IF-2; IF-1
D)   IF-2; IF-3
E)   IF-3; IF-1 C

Question 2

Which of the following represents a DNA mutation in the template strand that would convert serine to cysteine?

Accepted Answer

A)   5'-GCT-3' to 5'-GCA-3'
B)   5'-AGC-3' to 5'-TGC-3'
C)   5'-AGC-3' to 5'-UGC-3'
D)   5'-AGU-3' to 5'-UGU-3'
E)   5'-TCG-3' to 5'-TCC-3' A

Question 3

Erythromycin

Accepted Answer

A)   is specific for bacteria because it binds preferentially to the 50S ribosomal subunit, which is prokaryote-specific
B)   is specific for bacteria because it binds preferentially to the 40S ribosomal subunit, which is prokaryote-specific
C)   causes early termination of bacterial protein translation because it is an analog of release factor 3
D)   causes early termination of bacterial protein translation because it is an analog of EF-Tu and translocation ceases
E)   is not naturally-occurring A

Question 4

Class I and Class II aminoacyl-tRNA synthetases differ in
I. their major structures
II. the general size of aa that fits their active sites
III. exposure of their active sites
IV. fidelity in proofreading

Accepted Answer

A)   I only
B)   I and III
C)   I, III and IV
D)   II, III and IV
E)   I, II and III

Question 5

Polypeptide synthesis proceeds from the _____ to the _____.

Accepted Answer

A)   entrance site; exit site
B)   50S subunit; 30S subunit
C)   C-terminus; N-terminus
D)   N-terminus; C-terminus
E)   peptidyl site; aminoacyl site

Question 6

The first elongation event is

Accepted Answer

A)   the formation of the first peptide bond, when the amino N of amino acid 2 attacks the carboxyl C of methionine
B)   the formation of the first peptide bond, when the amino N of methionine attacks the carboxyl C of amino acid 2
C)   binding of eIF-2 or IF-2 to amino acid 2
D)   translocation of the ribosome to place empty tRNAmet into the E site
E)   binding of EF-G to tRNA-amino acid 2

Question 7

Which of the following aids in protein folding by completely sequestering a polypeptide from its environment?

Accepted Answer

A)   ubiquitin
B)   trigger factor
C)   chaperonin
D)   heat shock protein
E)   signal recognition particle

Question 8

What two elements of translation are paired by a Shine-Dalgarno sequence?

Accepted Answer

A)   initial tRNA with the initiation codon
B)   initial tRNA with the ribosomal A site
C)   mRNA with 23S rRNA of the ribosome
D)   mRNA with 16S rRNA of the ribosome
E)   mRNA with initial tRNA

Question 9

Chaperones such as GroEL and GroES generally bind to what regions of a polypeptide?

Accepted Answer

A)   hydrophobic regions
B)   acidic regions
C)   basic regions
D)   both acidic and basic regions
E)   neutral polar regions

Question 10

In eukaryotic cells, when a protein is to be translocated to the endoplasmic reticulum, what must occur for complete translation to occur?

Accepted Answer

A)   the N-terminus binds SRP which delivers the ribosome and growing peptide to the ER
B)   the N-terminus binds SRP which is then partially cleaved by a signal peptidase
C)   the ribosome must be translocated into the ER prior to initiation of translation
D)   the ribosome must be bound to the ER before translation begins
E)   a chaperone protein embedded in the ER membrane binds the N-terminus

Question 11

The 5' region of mRNA assists with its proper ribosomal placement during initiation of translation. In prokaryotes, the ____ is important for this purpose, while in eukaryotes, the ___ is used.

Accepted Answer

The answer of The 5' region of mRNA assists with...

Question 12

Which of the following describes the general three-dimensional structure of a tRNA?

Accepted Answer

A)   a cloverleaf shape with the anticodon and acceptor stem on "leaves" that are opposite each other
B)   an L shape with the anticodon at one end of the L and the acceptor stem at the other
C)   a large loop with the anticodon and 3' end in very close proximity to each other
D)   an elongated cylinder shape with the anticodon and acceptor stem at opposite ends
E)   since all tRNAs have very different three-dimensional structures, it is difficult to describe a general shape

Question 13

Describe the central dogma of molecular biology (to do this draw a diagram of the central dogma and describe all the arrows).

Accepted Answer

The answer of Describe the central dogma of molecular biology...

Question 14

Translation termination

Accepted Answer

A)   in prokaryotes requires a single release factor RF-1, which is also a GTPase
B)   in eukaryotes requires a single release factor eRF-1
C)   in eukaryotes requires one of three release factors: RF-1, RF-2 or RF-3
D)   none of the above

Question 15

What is the similarity between the amino acids that have only one codon each?

Accepted Answer

A)   they are aromatic amino acids
B)   they are the sulfur containing amino acids
C)   they are neutral polar amino acids
D)   they occur very infrequently in proteins
E)   none of the above

Question 16

The selectivity of aminoacyl-tRNA synthetases can be explained by

Accepted Answer

A)   the strength of even weak interactions of the amino acid within its catalytic binding site
B)   the topography of the enzymes' proofreading sites
C)   recognition of the anticodon loop only
D)   specific cations found in the catalytic binding site
E)   Both (
A)   and (
B)   are correct

Question 17

During the charging of a tRNA, what intermediate is formed?

Accepted Answer

A)   aminoacyl-adenylate
B)   aminoacyl-tRNA
C)   aminoacyl-ADP
D)   tRNA-adenylate
E)   none of the above

Question 18

Hydrolysis of GTP by EF-Tu is thermodynamically required for _____.

Accepted Answer

A)   proofreading
B)   transpeptidation
C)   translocation
D)   aminoacyl-tRNA binding to the ribosomal A site
E)   none of the above

Question 19

Which is NOT true of protein translation?

Accepted Answer

A)   About 10% of cell proteins are completely synthesized and reside in the cytosol.
B)   A single mRNA in the cytosol may have multiple ribosomes translating it at the same time.
C)   Ribosomes that reside permanently on the rough ER translate only proteins destined for secretion from the cell.
D)   Nascent proteins with a signal peptide at their amino terminus bind a signal recognition particle that binds an ER receptor.
E)   Polysomes are multiple ribosomes translating the same mRNA.

Question 20

Use the structure below to answer the following questions 
-The amino acid would be attached to this structure at

Accepted Answer

A)   1
B)   2
C)   3
D)   4
E)   5

Exam 16: Protein

In E. coli translation, _ aids with binding of the fMet-tRNA to the 30S subunit while _ blocks the A site.