Question 1

Use the following to answer questions 
Refer to the following sequence:
5' ...GGAGCUCGUUGUAUU... 3'
-This sequence is RNA because:

Accepted Answer

RNA contains uracil (U) instead of thymine (T), which is present in DNA.

Question 2

The wild-type sequence of a protein is ... asp-ile-cys-trp.… The sequence of a mutant form of the protein is ... asp-ile-tyr-trp.... Write all possible DNA sequences for the wild-type and mutant alleles of the gene for this protein; underline the changed nucleotide in the mutant allele.

Accepted Answer

The answer of The wild-type sequence of a protein is...

Question 3

Use the following to answer questions 
Refer to the following sequence:
5' ...GGAGCUCGUUGUAUU... 3'
-The sequence 5' ...GGAGCUCGUUGUAUU... 3'is changed to 5'… GGAGACUCGUUGUAUU… 3'. What would be the effect on the amino acid sequence?

Accepted Answer

The answer of Use the following to answer questions 
Refer...

Question 4

An mRNA has the stop codon 5' UAA 3'. What tRNA anticodon will bind to it?

Accepted Answer

Stop codons do not have corresponding tRNA anticodons because they signal the termination of protein synthesis.

Question 5

Which of the following statements does NOT describe the events in prokaryotic translation elongation?

Accepted Answer

The Shine-Dalgarno sequence is involved in the initiation of translation, not elongation.

Question 6

Use the following to answer questions 
An auxotrophic E. coli strain requires adenine to grow because of a mutation in a gene for an adenine synthesis enzyme. The following shows part of the wild-type and mutant alleles of the gene, including the start codon. The bottom strand is the template for transcription. $$\begin{array} { c c } 
\text { ade } 1 ^ { + } \text {wild-type allele } & \text { ade1 } ^ { - } \text {mutant allele } \
\text { 5'...TTATGGGCAAGATCCCA...3' } &  \text { 5'....TTA TGGGCTAGATCCCA...3' } \
\text { 3'...AATACCCGTTCTAGGGT...5' } & \text { 3'...AATATGGGCTAGATCCCA...3' }
\end{array}$$
-How does this mutation change the mRNA?

Accepted Answer

The mutation changes the third codon in the mRNA from AAG (lysine) to UAG (stop).

Question 7

Prokaryotic ribosomes are inhibited by antibiotics like tetracyclines. As eukaryotes, humans are unaffected by these antibiotics. However, ribosomes within human mitochondria more closely resemble prokaryotic ribosomes than eukaryotic ribosomes. Why aren't tetracyclines more toxic to humans if they can, in theory, inhibit mitochondrial ribosomes?

Accepted Answer

The answer of Prokaryotic ribosomes are inhibited by antibiotics like...

Question 8

Which of the following events is NOT part of prokaryotic translation initiation?

Accepted Answer

A peptide bond is formed during elongation, not initiation.

Question 9

Use the following to answer questions 
Refer to the following sequence:
5' ...GGAGCUCGUUGUAUU... 3'
-Which amino acids does this sequence code for, if the reading frame is as shown, starting from the correct end?

Accepted Answer

The sequence "GGAGCUCGUUGUAUU" translates to glycine (Gly), alanine (Ala), arginine (Arg), cysteine (Cys), and isoleucine (Ile) in the genetic code.

Question 10

Use the following to answer questions An auxotrophic E. coli strain requires adenine to grow because of a mutation in a gene for an adenine synthesis enzyme. The following shows part of the wild-type and mutant alleles of the gene, including the start codon. The bottom strand is the template for transcription. $$\begin{array} { c c } \text { ade } 1 ^ { + } \text {wild-type allele } & \text { ade1 } ^ { - } \text {mutant allele } \ \text { 5'...TTATGGGCAAGATCCCA...3' } & \text { 5'....TTA TGGGCTAGATCCCA...3' } \ \text { 3'...AATACCCGTTCTAGGGT...5' } & \text { 3'...AATATGGGCTAGATCCCA...3' } \end{array}$$ -E. coli strains that have both the original ade1^- mutant allele shown above and a mutant allele for a gene that encodes a lysine tRNA are able to make some normal ade1 enzyme. The mutant lysine tRNA allele makes a tRNA that has one base that is different from the wild-type tRNA. Which of the following statements would help explain how the lysine tRNA mutation allows synthesis of the normal ade1 enzyme? (Select all that apply.)

Accepted Answer

The mutation in the lysine tRNA gene likely changes the anticodon so that it can pair with the UAG stop codon, allowing the incorporation of lysine and bypassing the premature stop signal in the mutant allele.

Question 11

A yeast strain was exposed to chemical mutagen. As expected, exposure to mutagen resulted in a DNA sequence change in an essential gene you examined. Yet this mutation did not result in any lethal phenotype. Which of the following answers would BEST explain this apparent discrepancy?

Accepted Answer

The answer of A yeast strain was exposed to chemical...

Question 12

Write the anticodon, with correct polarity, of all tRNAs that will bind to the mRNA codon 5' UCG 3', considering wobble-base pairing rules.

Accepted Answer

The answer of Write the anticodon, with correct polarity, of...

Question 13

Describe the events in prokaryotic translation elongation.

Accepted Answer

The answer of Describe the events in prokaryotic translation elongation....

Question 14

List three differences between prokaryotic and eukaryotic translation.

Accepted Answer

The answer of List three differences between prokaryotic and eukaryotic...

Question 15

Use the following to answer questions 
An auxotrophic E. coli strain requires adenine to grow because of a mutation in a gene for an adenine synthesis enzyme. The following shows part of the wild-type and mutant alleles of the gene, including the start codon. The bottom strand is the template for transcription. $$\begin{array} { c c } 
\text { ade } 1 ^ { + } \text {wild-type allele } & \text { ade1 } ^ { - } \text {mutant allele } \
\text { 5'...TTATGGGCAAGATCCCA...3' } &  \text { 5'....TTA TGGGCTAGATCCCA...3' } \
\text { 3'...AATACCCGTTCTAGGGT...5' } & \text { 3'...AATATGGGCTAGATCCCA...3' }
\end{array}$$
-How does the mutation affect the enzyme?

Accepted Answer

The answer of Use the following to answer questions 
An...

Question 16

Describe the events in prokaryotic translation initiation.

Accepted Answer

The answer of Describe the events in prokaryotic translation initiation....

Question 17

E. coli only has a single tryptophan tRNA gene. Why, given this arrangement, might it be difficult to identify mutants that alter the anticodon of this tRNA gene?

Accepted Answer

The answer of E. coli only has a single tryptophan...

Question 18

Use the following to answer questions 
Refer to the following sequence:
5' ...GGAGCUCGUUGUAUU... 3'
-The nucleotide sequence 5'...GGAGCUCGUUGUAUU... 3' is changed to 5'GGAGACUCGUUGUAUU 3'. Why does or why doesn't the amino acid sequence change?

Accepted Answer

The answer of Use the following to answer questions 
Refer...

Question 19

Use the following to answer questions An auxotrophic E. coli strain requires adenine to grow because of a mutation in a gene for an adenine synthesis enzyme. The following shows part of the wild-type and mutant alleles of the gene, including the start codon. The bottom strand is the template for transcription. $$\begin{array} { c c } \text { ade } 1 ^ { + } \text {wild-type allele } & \text { ade1 } ^ { - } \text {mutant allele } \ \text { 5'...TTATGGGCAAGATCCCA...3' } & \text { 5'....TTA TGGGCTAGATCCCA...3' } \ \text { 3'...AATACCCGTTCTAGGGT...5' } & \text { 3'...AATATGGGCTAGATCCCA...3' } \end{array}$$ -E. coli strains that have both the original ade1^- mutant allele shown above and a mutant allele for a gene that encodes a lysine tRNA are able to make some normal ade1 enzyme. The mutant lysine tRNA allele makes a tRNA that has one base that is different from the wild-type tRNA. Why might the mutant lysine tRNA allele affect overall cell growth?

Accepted Answer

The mutant tRNA^lysine can recognize the UAG stop codon as a lysine codon, allowing translation to continue and produce a full-length protein instead of terminating prematurely.

Question 20

Which of the following mRNA codons will bind to the tRNA anticodon 5' GCU 3', considering wobble-base pairing rules.

Accepted Answer

The answer of Which of the following mRNA codons will...

Quiz 15: The Genetic Code and Translation

Use the following to answer questions Refer to the following sequence: 5' ...GGAGCUCGUUGUAUU... 3' -This sequence is RNA because: