Question 1

Which property of the genetic code allows for multiple codons to encode the same amino acid?

Accepted Answer

Degeneracy

Question 2

A mutation changes the DNA sequence from $$5'-ATG-GAA-TGC-3' to$$ $$5'-ATG-GAA-TTGC-3'. $$What type of mutation has occurred, and what is the likely effect on the reading frame?

Accepted Answer

An insertion mutation; the reading frame is shifted

Question 3

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

Accepted Answer

Beadle and Tatum's experiment with Neurospora

Question 4

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

Accepted Answer

A frameshift mutation, altering all downstream amino acids

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 to initiate transcription

Question 6

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

Accepted Answer

$$TATAAT$$

Question 7

What is the main difference between rho-dependent and rho-independent transcription termination in prokaryotes?

Accepted Answer

Rho-dependent termination requires a protein factor, while rho-independent relies on a stem-loop structure and uracil-rich sequence

Question 8

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

Accepted Answer

Failure to initiate transcription at the correct promoter

Question 9

Given the DNA template strand $$3'-TAC-GGT-CAA-TGC-5'$$, what is the corresponding mRNA sequence?

Accepted Answer

$$5'-AUG-CCA-GUU-ACG-3'$$

Question 10

Which of the following statements about the genetic code is FALSE?

Accepted Answer

Each amino acid is specified by only one codon

Question 11

In prokaryotic transcription, which strand of DNA is used as the template for RNA synthesis?

Accepted Answer

The strand oriented 3' to 5' relative to the gene

Question 12

Which of the following best explains why insertion of three base pairs into a gene does not alter the reading frame?

Accepted Answer

Three bases correspond to one codon, so the reading frame is preserved

Question 13

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

Accepted Answer

It encodes multiple polypeptides from a single mRNA

Question 14

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

Accepted Answer

A premature stop codon is introduced, truncating the protein

Question 15

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

Accepted Answer

5' to 3'

Question 16

Which of the following best describes the outcome of the Beadle and Tatum experiment with Neurospora?

Accepted Answer

It demonstrated that each gene encodes a specific enzyme

Question 17

A mutation changes a codon from $$UUA to$$ $$UAA. $$What is the consequence of this mutation?

Accepted Answer

A stop codon is introduced, leading to premature termination

Question 18

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

Accepted Answer

It is overlapping

Question 19

What is the function of the core enzyme of prokaryotic RNA polymerase?

Accepted Answer

It synthesizes RNA but cannot initiate transcription without the sigma factor

The Genetic Code and Prokaryotic Transcription: Study Notes

Guida di studio - Domande di pratica

Study guide - Flashcard