Question 1

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

Accepted Answer

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

Question 2

A mutation changes the DNA sequence from $$5'	ext{-}AGGCTTACG-3' to$$ $$5'	ext{-}AGGCTTATG-3'. $$The resulting mRNA is $$5'	ext{-}AGGCUUAUG-3'. If $$the original codon coded for tyrosine (Tyr), but the mutated codon codes for the same amino acid, what type of mutation is this?

Accepted Answer

Silent mutation

Question 3

Which of the following is a direct result of a frameshift mutation?

Accepted Answer

The reading frame of the mRNA is altered, changing all downstream amino acids.

Question 4

In prokaryotic transcription, what is the primary role of the sigma ($$\sigma) $$factor?

Accepted Answer

To recognize and bind to the promoter region of DNA

Question 5

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

Accepted Answer

$$	ext{TATAAT}$$

Question 6

Which of the following best describes polycistronic mRNA?

Accepted Answer

An mRNA that contains multiple genes, each with its own start and stop codon

Question 7

Which of the following is NOT a post-transcriptional modification in eukaryotes?

Accepted Answer

Addition of a sigma factor

Question 8

A eukaryotic gene contains the following elements: enhancer, TATA box, exons, and introns. Which element is a cis-acting DNA sequence that increases transcription efficiency?

Accepted Answer

Enhancer

Question 9

Alternative splicing allows a single gene to:

Accepted Answer

Produce multiple different mRNA transcripts and thus different proteins

Question 10

Which of the following best describes the function of the CRISPR-Cas9 system in genome editing?

Accepted Answer

It introduces double-stranded breaks at specific DNA sequences, allowing for targeted gene modification.

Question 11

A patient with sickle cell disease undergoes CRISPR-Cas9 therapy. Which specific genetic change is made to correct the disease?

Accepted Answer

A thymine (T) is replaced with an adenine (A) in the $$\beta-$$globin gene.

Question 12

Which repair pathway is most likely used after a CRISPR-Cas9-induced double-stranded break if a donor template is provided?

Accepted Answer

Homology-directed repair (HDR)

Question 13

Which of the following is a trans-acting factor in eukaryotic transcription?

Accepted Answer

Transcription factor protein

Question 14

A nonsense mutation in a gene results in:

Accepted Answer

A premature stop codon, truncating the protein

Question 15

Which of the following equations correctly predicts the probability of a specific 6-nucleotide sequence occurring in a random DNA sequence?

Accepted Answer

$$P = (1/4)^6$

Question 16

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

Accepted Answer

Once translation begins, codons are read continuously without breaks.

Question 17

Which of the following is a key difference between prokaryotic and eukaryotic transcription?

Accepted Answer

Eukaryotic transcription requires chromatin remodeling, while prokaryotic transcription does not.

Question 18

Which of the following is the correct order of events in eukaryotic mRNA processing?

Accepted Answer

Capping, splicing, polyadenylation

Question 19

A mutation in the TATA box of a eukaryotic gene would most likely affect:

Accepted Answer

The binding of RNA polymerase II and initiation of transcription

Genetic Code, Transcription, and CRISPR-Cas Genome Editing: Study Notes for Genetics Students

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