Q: A prokaryotic gene is transcribed from the following DNA template strand: $$3'\text{-}TAC\,GGC\,TTA\,GCC\,5'. $$What is the sequence of the resulting mRNA?

$$5'\text{-}AUG\,CCG\,AAU\,CGG\,3'$$

Q: If a gene is located on the DNA strand running $$5'\text{-}ATG\,GCC\,TAA\,3'$$, which strand will serve as the template for transcription?

The strand running $$3'\text{-}TAC\,CGG\,ATT\,5'$$

Question 1

Which property of the genetic code allows for silent mutations, where a change in the DNA sequence does not alter the amino acid sequence of the protein?

Accepted Answer

The code is degenerate

Question 2

A mutation changes the DNA sequence from $$5'	ext{-}ATG\,GAA\,TGC\,TAA\,3' to$$ $$5'	ext{-}ATG\,GAA\,TGC\,CAA\,3'. $$What is the most likely effect on the resulting protein?

Accepted Answer

The protein will have an amino acid substitution at the last position

Question 3

Which experiment led to the 'one gene-one enzyme' hypothesis?

Accepted Answer

Beadle and Tatum's Neurospora experiment

Question 4

If a single base is inserted into a coding sequence, what is the most likely outcome?

Accepted Answer

A frameshift mutation will occur

Question 5

Which of the following best describes the role of the sigma ($$\sigma) $$factor in prokaryotic transcription?

Accepted Answer

It recognizes and binds to the promoter region

Question 6

A prokaryotic gene is transcribed from the following DNA template strand: $$3'	ext{-}TAC\,GGC\,TTA\,GCC\,5'. $$What is the sequence of the resulting mRNA?

Accepted Answer

$$5'	ext{-}AUG\,CCG\,AAU\,CGG\,3'$$

Question 7

Which of the following is true about rho-independent transcription termination in prokaryotes?

Accepted Answer

It involves a GC-rich stem-loop followed by a uracil-rich sequence

Question 8

A mutation in the Pribnow box (–10 region) of a bacterial promoter would most likely result in:

Accepted Answer

Decreased initiation of transcription

Question 9

Which of the following statements about the central dogma of genetics is correct?

Accepted Answer

RNA is translated into protein

Question 10

If a gene is located on the DNA strand running $$5'	ext{-}ATG\,GCC\,TAA\,3'$$, which strand will serve as the template for transcription?

Accepted Answer

The strand running $$3'	ext{-}TAC\,CGG\,ATT\,5'$$

Question 11

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

Accepted Answer

Each codon specifies only one amino acid

Question 12

A bacterial mRNA is described as polycistronic. What does this mean?

Accepted Answer

It encodes multiple polypeptides from a single mRNA

Question 13

Which of the following is a direct result of a single base-pair deletion in a coding region?

Accepted Answer

A frameshift mutation

Question 14

What is the main difference between the RNA polymerase core enzyme and the holoenzyme in prokaryotes?

Accepted Answer

The holoenzyme includes the sigma ($$\sigma) $$factor for promoter recognition

Question 15

Which of the following sequences is most likely to be found at the –10 region (Pribnow box) of a prokaryotic promoter?

Accepted Answer

$$TATAAT$$

Question 16

A suppressor mutation restores the reading frame after a frameshift. Which scenario best illustrates this?

Accepted Answer

A single base insertion followed by a single base deletion nearby

Question 17

Which of the following is NOT a property of the genetic code?

Accepted Answer

It is overlapping

Question 18

During prokaryotic transcription, which direction is the RNA strand synthesized?

Accepted Answer

$$5' \rightarrow 3'$$

Question 19

Which of the following best describes rho-dependent termination of transcription in prokaryotes?

Accepted Answer

It requires the rho protein to unwind the RNA-DNA hybrid

Question 20

A mutation in the gene encoding the sigma ($$\sigma) $$factor would most likely result in which of the following?

Accepted Answer

Inability of RNA polymerase to recognize promoters

Chapter 12: The Genetic Code and Prokaryotic Transcription – Study Notes

Guida di studio - Domande di pratica

Study guide - Flashcard