Question 1

Which of the following statements correctly describes a key difference between prokaryotic and eukaryotic mRNA?

Accepted Answer

Prokaryotic mRNAs can be polycistronic, encoding multiple proteins per transcript, while eukaryotic mRNAs are typically monocistronic.

Question 2

A mutation changes a codon from $$	ext{UAC} ($$tyrosine) to $$	ext{UAA} ($$stop). What type of mutation is this?

Accepted Answer

Nonsense mutation

Question 3

Which enzyme is responsible for attaching the correct amino acid to its corresponding tRNA?

Accepted Answer

Aminoacyl tRNA synthetase

Question 4

Given the mRNA sequence $$5'	ext{AUG GCU UGA}\ 3'$$, what is the resulting peptide sequence?

Accepted Answer

Met-Ala-Stop

Question 5

A patient with Huntington's disease has increased CAG repeats in the huntingtin gene. What is the molecular consequence of this mutation?

Accepted Answer

Production of a huntingtin protein with an expanded polyglutamine tract

Question 6

Which of the following best describes a frameshift mutation?

Accepted Answer

A mutation caused by the insertion or deletion of nucleotides not in multiples of three, altering the reading frame

Question 7

During translation initiation in eukaryotes, which of the following is TRUE?

Accepted Answer

The initiator tRNA carries methionine and binds to the start codon $$	ext{AUG}.$$

Question 8

Which of the following mutations is most likely to be observed when sequencing the DNA polymerase gene from 1000 humans?

Accepted Answer

Silent mutation

Question 9

A forward mutation is defined as:

Accepted Answer

A mutation that converts a wild-type allele to a mutant allele

Question 10

Which of the following is a function of the untranslated regions (UTRs) in mRNA?

Accepted Answer

They regulate mRNA stability and translation efficiency.

Question 11

If a mutation in a gene is reverted by a second mutation elsewhere in the same gene, this is called:

Accepted Answer

Intragenic reversion

Question 12

Which of the following best explains why codons consist of three nucleotides?

Accepted Answer

Because two nucleotides per codon would not provide enough combinations to encode all 20 amino acids.

Question 13

Which of the following is TRUE regarding translation in prokaryotes?

Accepted Answer

Translation can begin before transcription is complete.

Question 14

A missense mutation in a gene results in which of the following?

Accepted Answer

A change in the DNA sequence that results in a different amino acid being incorporated into the protein

Question 15

Which of the following scenarios best illustrates a second-site reversion?

Accepted Answer

A mutation in gene A is compensated by a mutation in gene B, restoring the wild-type phenotype.

Question 16

Which of the following is the correct order of events during translation?

Accepted Answer

Initiation, elongation, termination

Question 17

A DNA sequence $$5'	ext{ATG GAA TGA}\ 3' is $$transcribed and translated. What is the resulting peptide sequence?

Accepted Answer

Met-Glu-Stop

Question 18

Which of the following statements about tRNA is correct?

Accepted Answer

tRNA pairs its anticodon with the mRNA codon and delivers the corresponding amino acid.

Question 19

A mutation deletes two nucleotides from the coding region of a gene. What is the most likely effect on the protein product?

Accepted Answer

The reading frame will be shifted, resulting in a completely altered amino acid sequence downstream of the mutation.

Gene Expression & Translation of mRNA: Key Concepts in Genetics

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