Question 1

Which of the following statements best describes the degeneracy of the genetic code?

Accepted Answer

Most amino acids are specified by more than one codon.

Question 2

A mutation changes a codon from UAU (tyrosine) to UAA in a gene. What is the most likely consequence of this mutation?

Accepted Answer

Translation will terminate prematurely, producing a truncated protein.

Question 3

Which of the following is TRUE regarding the initiation of transcription in eukaryotes?

Accepted Answer

General transcription factors are required for RNA polymerase II to bind to the promoter.

Question 4

Which codon serves as the universal start codon for translation, and what amino acid does it encode?

Accepted Answer

AUG; methionine

Question 5

A researcher observes that a single mRNA molecule can produce two different polypeptides depending on the initiation site. What genetic phenomenon does this illustrate?

Accepted Answer

Overlapping genes

Question 6

Which of the following best explains the wobble hypothesis?

Accepted Answer

The third base of the codon can form non-standard base pairs with the anticodon, allowing some tRNAs to recognize multiple codons.

Question 7

Which of the following is a function of introns in eukaryotic genes?

Accepted Answer

They allow for alternative splicing, increasing protein diversity.

Question 8

In human mitochondria, the codon UGA is interpreted differently than in the universal genetic code. What does UGA code for in human mitochondria?

Accepted Answer

It codes for tryptophan.

Question 9

Which of the following best describes the role of the sigma (σ) factor in bacterial transcription?

Accepted Answer

It recognizes and binds to promoter sequences, guiding RNA polymerase to the correct initiation site.

Question 10

A mutation in the DNA changes a codon from UGG (tryptophan) to UGA. What type of mutation is this, and what is its likely effect?

Accepted Answer

Nonsense mutation; results in premature termination of translation

Question 11

Which of the following posttranscriptional modifications occurs in eukaryotic mRNA but not in prokaryotic mRNA?

Accepted Answer

Addition of a 7-methylguanosine cap at the 5' end

Question 12

Which of the following equations correctly represents the number of possible codons given four different RNA bases and a triplet code?

Accepted Answer

$$4^3 = 64$

Question 13

A gene contains the following sequence: 5'-TACGGT-3'. What is the sequence of the mRNA transcribed from this DNA template?

Accepted Answer

5'-AUGCCA-3'

Question 14

Which of the following statements about RNA polymerase is FALSE?

Accepted Answer

RNA polymerase requires a primer to initiate synthesis.

Question 15

Which of the following best describes the function of spliceosomes in eukaryotic cells?

Accepted Answer

They remove introns from pre-mRNA and join exons together.

Question 16

A patient has a genetic disorder caused by a mutation that disrupts the polyadenylation signal (AAUAAA) in a gene. What is the most likely effect on the mRNA produced from this gene?

Accepted Answer

The mRNA will not be properly cleaved and polyadenylated, leading to instability and rapid degradation.

Question 17

Which of the following is an example of a cis-acting DNA element involved in transcription regulation?

Accepted Answer

Enhancer

Question 18

Which process can result in the production of different proteins from the same gene in eukaryotes?

Accepted Answer

Alternative splicing

Question 19

Which of the following best describes substitution editing during RNA editing?

Accepted Answer

The identity of individual nucleotide bases is altered after transcription.

Question 20

Which of the following statements about the universality of the genetic code is correct?

Accepted Answer

The genetic code is nearly universal, but some exceptions exist in mitochondrial DNA.

Chapter 12: The Genetic Code and Transcription – Study Notes

Guida di studio - Domande di pratica

Study guide - Flashcard