Question 1

Which of the following best explains why transcription and translation can occur simultaneously in prokaryotic cells, but not in eukaryotic cells?

Accepted Answer

Prokaryotic cells lack a nuclear envelope, allowing ribosomes to access mRNA as it is being transcribed.

Question 2

A DNA sequence has the following template strand: 3'-TACGGTACG-5'. What is the corresponding mRNA sequence produced during transcription?

Accepted Answer

5'-AUGCCAUGC-3'

Question 3

Using the genetic code, what amino acid sequence is produced from the mRNA sequence 5'-AUGGCCUAA-3'?

Accepted Answer

Methionine-Alanine-Stop

Question 4

Which of the following is a function of the 5' cap added to eukaryotic mRNA during RNA processing?

Accepted Answer

Facilitates ribosome binding to the mRNA

Question 5

A mutation changes a codon from UAU (tyrosine) to UAA (stop). What type of mutation is this?

Accepted Answer

Nonsense mutation

Question 6

Which enzyme is responsible for attaching the correct amino acid to its corresponding tRNA?

Accepted Answer

Aminoacyl-tRNA synthetase

Question 7

What is the effect of a frameshift mutation caused by the insertion of a single nucleotide within the coding region of a gene?

Accepted Answer

It alters the reading frame, potentially changing every amino acid downstream of the mutation.

Question 8

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

Accepted Answer

It is redundant, meaning multiple codons can code for the same amino acid.

Question 9

During translation, which site on the ribosome holds the tRNA carrying the growing polypeptide chain?

Accepted Answer

P site

Question 10

A tobacco plant is engineered to express a firefly gene, resulting in bioluminescence. What does this demonstrate about the genetic code?

Accepted Answer

The genetic code is nearly universal among organisms.

Question 11

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

Accepted Answer

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

Question 12

What is the consequence of a silent mutation in a gene?

Accepted Answer

The amino acid sequence of the protein remains unchanged.

Question 13

Which of the following modifications occurs to the 3' end of a eukaryotic pre-mRNA during RNA processing?

Accepted Answer

Addition of a poly-A tail

Question 14

If a gene is transcribed simultaneously by several RNA polymerases, what is the likely outcome?

Accepted Answer

Multiple mRNA transcripts are produced, increasing protein synthesis.

Question 15

Which of the following is NOT a post-translational modification?

Accepted Answer

Addition of a poly-A tail

Question 16

A mutation changes the DNA sequence from 5'-ATG-3' to 5'-ATA-3'. What is the effect on the protein, using the triplet code?

Accepted Answer

Methionine is replaced by isoleucine, resulting in a missense mutation.

Question 17

Which of the following best describes the process of alternative RNA splicing?

Accepted Answer

Different combinations of exons are joined together, allowing a single gene to code for multiple polypeptides.

Question 18

Which of the following is true about the directionality of transcription and translation?

Accepted Answer

Transcription and translation both proceed in the 5' to 3' direction.

Question 19

A polypeptide destined for secretion from a eukaryotic cell is synthesized by ribosomes attached to which cellular structure?

Accepted Answer

Endoplasmic reticulum

Gene Expression: From Gene to Protein (Transcription, Translation, and Mutations)

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