Question 1

Which of the following statements best describes the direction of RNA synthesis during transcription?

Accepted Answer

RNA is synthesized in the 5' → 3' direction using the template strand.

Question 2

In bacteria, what is the role of the sigma factor during transcription initiation?

Accepted Answer

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

Question 3

Which sequence is typically found about 10 bases upstream of the transcription start site in bacterial promoters?

Accepted Answer

TATAAT

Question 4

What is the main difference between transcription termination in bacteria and eukaryotes?

Accepted Answer

Bacteria use a hairpin structure, while eukaryotes use a poly(A) signal followed by RNA cleavage.

Question 5

Which of the following best explains why eukaryotic mRNA must be processed before translation?

Accepted Answer

Eukaryotic mRNA contains introns that must be removed, and it requires a 5' cap and a 3' poly(A) tail for stability and translation.

Question 6

A mutation in the gene encoding a spliceosome component would most likely result in which of the following?

Accepted Answer

Retention of introns in the mature mRNA, potentially leading to nonfunctional proteins.

Question 7

Which of the following best describes the function of the 5' cap added to eukaryotic mRNA?

Accepted Answer

It enables ribosomes to bind to the mRNA and protects the mRNA from degradation.

Question 8

During translation, which site in the ribosome does the incoming aminoacyl-tRNA first bind to?

Accepted Answer

A site

Question 9

Which of the following statements about tRNA is correct?

Accepted Answer

Each tRNA has an anticodon that base-pairs with a codon on mRNA and an amino acid attached at the 3' end.

Question 10

A scientist discovers a cell with 61 different codons but only 40 types of tRNA. Which concept explains this observation?

Accepted Answer

The wobble hypothesis, where the third base of the codon can form nonstandard base pairs.

Question 11

Which of the following best describes the role of aminoacyl-tRNA synthetase?

Accepted Answer

It attaches the correct amino acid to its corresponding tRNA using ATP.

Question 12

In bacteria, what would be the most likely consequence of a mutation that disrupts the -10 box in a promoter?

Accepted Answer

Sigma factor would not recognize the promoter, and transcription initiation would be impaired.

Question 13

Which of the following is a key difference between gene expression in prokaryotes and eukaryotes?

Accepted Answer

In eukaryotes, transcription occurs in the nucleus and translation occurs in the cytoplasm.

Question 14

A mutation changes a single base in the coding region of a gene, resulting in a different amino acid in the protein. Which term best describes this type of mutation?

Accepted Answer

Missense mutation

Question 15

Which of the following best explains why proteins produced by different alleles of the same gene may differ in function?

Accepted Answer

Different alleles have different DNA sequences, which can lead to changes in the amino acid sequence of the protein.

Question 16

During translation elongation, what is the correct order of events?

Accepted Answer

Arrival of aminoacyl-tRNA, peptide bond formation, translocation

Question 17

Which of the following post-translational modifications can alter the activity of a protein?

Accepted Answer

Addition of a phosphate group by an enzyme

Question 18

A patient has a genetic disorder caused by a defect in molecular chaperones. Which cellular process is most likely to be directly affected?

Accepted Answer

Protein folding

Question 19

Which of the following best describes the flow of genetic information in a eukaryotic cell?

Accepted Answer

$$DNA \rightarrow mRNA \rightarrow Protein$$

Question 20

Which of the following is true about the ribosome's catalytic activity during translation?

Accepted Answer

The ribosome is a ribozyme because its active site is made of rRNA, which catalyzes peptide bond formation.

Transcription and Translation: Gene Expression in Bacteria and Eukaryotes

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