Deck 18: The Mechanism of Translation II: Elongation and Termination

Question 1

Pyrrolysine and ____________ are examples of unusual amino acids that can be incorporated into proteins using stop codons.

Answer 1

selenocysteine

Question 2

During translation elongation each translocation step moves the mRNA _______ through the ribosome.

Answer 2

one codon ( three nucleotides

Question 3

Which of the following molecules does not resemble a tRNA molecule?

A)tmRNA
B)RRF
C)puromycin
D)suppressor tRNA
E)EF-Tu

Answer 3

E

Question 4

tmRNA resembles tRNA except for the fact that it lacks a(n)_________ and a _____ loop.

Question 5

Which of the following are the three naturally occurring stop codons?

A)UAG,UAA,UGG
B)UGA,UGG,UAG
C)UAA,AUU,GUU
D)UAG,UAA,UGA
E)UAA,UUA,GGA

Question 6

Place the steps of translation elongation in the correct order.(1)Peptidyl transferase forms a peptide bond between the peptide in the P site and the newly arrived aminoacyl-tRNA in the A site.(2)EF-G,with GTP,translocates peptidyl-tRNA to the P site.(3)EF-Tu,with GTP,binds an aminoacyl-tRNA to the ribosomal A site.

A)3,1,2
B)3,2,1
C)1,2,3
D)1,3,2
E)2,3,1

Question 7

Which of the following statements is not true concerning the genetic code?

A)It is an overlapping code.
B)It is a "comma-less" code.
C)It is an almost universal code.
D)It is capable of wobble base pairing.
E)It is a triplet code.

Question 8

The hydrolysis of _________ is necessary for the release of EF-G from the ribosome,which significantly accelerates translocation.

Question 9

Which of the following antibiotics does not inhibit protein synthesis by binding to the ribosome?

A)chloroamphenicol
B)streptomycin
C)tetracycline
D)erythromycin
E)ampicillin

Question 10

Peptidyl transferase activity is located in the _________ subunit of the ribosome.

Question 11

Proteins are synthesized in the __________ to ____________ direction by the ribosome.

Question 12

Which of the following characteristics is not a characteristic of a G protein?

A)They bind GMP for activation.
B)They have intrinsic GTPase activity.
C)Binding of GTP activates their function.
D)Cleavage of bound GTP to GDP inactivates them.
E)They cycle between three conformational states.

Question 13

Misfolding of nascent proteins can occur when inappropriate _______________ regions of the protein interact with each other.

Question 14

There are only 64 codons in the genetic code.

Question 15

The antibiotic puromycin resembles a(n)___________ and can bind to the A site of the ribosome.

Question 16

EF-Tu is an important protein in cells whose function is to

A)properly fold proteins.
B)ensure proper ribosome assembly.
C)escort aminoacyl-tRNA to the ribosome.
D)protect rRNA from degradation by RNases.
E)stabilize mRNA within the ribosome.

Question 17

The genetic code is composed of codons where each codon contains ____________ bases and encodes for ___________ amino acid.

Question 18

Misfolded proteins can be toxic to cells and lead to serious disease in humans.Which of the following diseases is caused by a misfolded protein?

A)sickle cell anemia
B)bovine spongiform encephalitis
C)diabetes
D)Burkitts Lymphoma
E)HIV-AIDS

Question 19

Amber mutation suppressors are _____________ molecules.

Question 20

The correct folding of proteins in the cell is accomplished with the help of __________ __________.

Question 21

Amber mutations are mutations that create termination codons in the middle of an mRNA causing premature translation termination.

Question 22

EF-Tu is one of the most abundant proteins in the cell.

Question 23

A transversion is a mutation in the genetic code that changes a purine to a pyrimidine.

Question 24

Mitochondrial mRNAs contain codons that don't conform to the universal genetic code.

Question 25

tmRNA is involved in rescuing the ribosome from non-stop translation.

Question 26

Ribosome recycling factor (RRF)is another RNA molecule that resembles tRNA.

Question 27

Wobble base pairing can occur between tRNA and the third base in the mRNA codon.

Question 28

The E site of the ribosome plays a critical role in the entrance of tRNA into the ribosome.

Question 29

Peptidyl transferase activity can be inhibited in prokaryotic cells by penicillin.

Question 30

Translation termination release factors are tRNA molecules that have anticodons complimentary to the three stop codons.

Question 31

Noller,Mankin,and colleagues,using KSP particle data and reconstitution experiments,concluded that the minimal component necessary for peptidyl transferase activity is the 23S rRNA.

Question 32

Both prokaryotes and eukaryotes rely on tmRNA to deal with aberrant termination.