Q: If the DNA template strand has the sequence $$5'\text{-}ACATCAATAACT\text{-}3'$$, what is the corresponding mRNA sequence produced during transcription?

$$5'\text{-}UGUAGUUAUUGA\text{-}3'$$

Question 1

Which of the following statements best explains why the genetic code is described as 'degenerate'?

Accepted Answer

A given amino acid can be specified by more than one codon.

Question 2

A mutation changes a codon from AAA to UAA in the middle of an mRNA sequence. What is the most likely effect on the resulting protein?

Accepted Answer

The protein will be shorter due to premature termination.

Question 3

Which of the following codons serves as the universal start codon for translation in most organisms?

Accepted Answer

$$\mathrm{AUG}$$

Question 4

If the DNA template strand has the sequence $$5'	ext{-}ACATCAATAACT	ext{-}3'$$, what is the corresponding mRNA sequence produced during transcription?

Accepted Answer

$$5'	ext{-}UGUAGUUAUUGA	ext{-}3'$$

Question 5

Which of the following is NOT a function of the promoter region in bacterial transcription?

Accepted Answer

Signals where transcription ends

Question 6

A frameshift mutation occurs due to the insertion of two nucleotides in a coding region. What is the most likely consequence?

Accepted Answer

All codons downstream of the insertion are altered, potentially changing the entire protein sequence.

Question 7

Which of the following best describes the 'wobble hypothesis' in tRNA-codon pairing?

Accepted Answer

The third base of the codon can form non-standard base pairs with the first base of the tRNA anticodon.

Question 8

In the context of overlapping genes, what is a potential disadvantage for an organism?

Accepted Answer

A single mutation can affect multiple proteins encoded by overlapping reading frames.

Question 9

Which of the following statements about transcription in bacteria is TRUE?

Accepted Answer

The sigma factor provides specificity for promoter recognition.

Question 10

A bacterial gene is not being transcribed, but sequencing reveals no mutations in the coding region. Which is the most likely explanation?

Accepted Answer

A mutation in the promoter region prevents RNA polymerase binding.

Question 11

Which of the following codons is a stop codon in the standard genetic code?

Accepted Answer

$$\mathrm{UAA}$$

Question 12

What is the main reason that the genetic code is considered 'nearly universal'?

Accepted Answer

Most organisms use the same codon assignments, with a few exceptions in mitochondria and some protists.

Question 13

Which of the following best describes the relationship between the coding DNA strand and the mRNA produced during transcription?

Accepted Answer

They are identical except that mRNA contains uracil (U) instead of thymine (T).

Question 14

Which of the following is a feature of intrinsic (Rho-independent) transcription termination in bacteria?

Accepted Answer

It involves the formation of a GC-rich hairpin structure in the RNA followed by a string of uracils.

Question 15

A viral mRNA sequence is 5'-UUAAUGCAUACCUAUGCAGACCCUUGGAAUGGCCCACUUGGACU-3'. If overlapping genes are possible, how many different polypeptide sequences can be produced from this mRNA?

Accepted Answer

3

Question 16

Which of the following best explains why the genetic code is described as 'comma-less'?

Accepted Answer

Once translation begins, codons are read continuously without breaks until a stop codon is reached.

Question 17

Which of the following is a consensus sequence found in bacterial promoters that is important for RNA polymerase binding?

Accepted Answer

$$\mathrm{TATAAT} (-10 $$region, Pribnow box)

Question 18

Which of the following statements about the directionality of transcription is correct?

Accepted Answer

RNA is synthesized in the 5' to 3' direction.

Question 19

Which of the following is a direct result of a nonsense mutation in a gene?

Accepted Answer

A stop codon is introduced, resulting in a truncated protein.

Question 20

Which of the following is true about coupled transcription and translation in bacteria?

Accepted Answer

Ribosomes can begin translating mRNA while it is still being synthesized.

Genetic Code and Transcription: Structure, Function, and Mechanisms

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