Question 1

Which of the following best describes the central dogma of molecular biology as depicted in the first image?

Accepted Answer

DNA is transcribed into RNA, which is then translated into protein.

Question 2

During transcription, which enzyme is responsible for synthesizing RNA from a DNA template?

Accepted Answer

RNA polymerase

Question 3

In eukaryotic cells, what modification is added to the 5′ end of pre-mRNA during RNA processing?

Accepted Answer

A modified guanine nucleotide (5′ cap)

Question 4

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

Accepted Answer

There are 64 possible codons, but only 20 amino acids.

Question 5

What is the function of tRNA during translation?

Accepted Answer

It brings amino acids to the ribosome and matches them to the mRNA codon.

Question 6

Which site on the ribosome holds the tRNA carrying the growing polypeptide chain?

Accepted Answer

P site

Question 7

A mutation causes a single nucleotide change in the DNA sequence, resulting in a codon change from UAU to UAA. What is the likely consequence for the protein product?

Accepted Answer

Premature termination of translation

Question 8

In prokaryotes, why can translation begin before transcription is finished?

Accepted Answer

Transcription and translation both occur in the cytoplasm.

Question 9

Which of the following is NOT a function of the 5′ cap and poly-A tail added to eukaryotic mRNA?

Accepted Answer

Directly catalyzing peptide bond formation

Question 10

Which process removes introns from pre-mRNA and joins exons together?

Accepted Answer

RNA splicing

Question 11

A ribozyme is best described as:

Accepted Answer

A catalytic RNA molecule

Question 12

Which of the following best explains why the genetic code is described as 'redundant' but not 'ambiguous'?

Accepted Answer

Multiple codons can specify the same amino acid, but each codon specifies only one amino acid.

Question 13

During the elongation phase of translation, what is the correct order of sites that a tRNA moves through in the ribosome?

Accepted Answer

A site → P site → E site

Question 14

Which of the following sequences is complementary to the DNA template strand 5′-ATGCGT-3′ during transcription?

Accepted Answer

3′-UACGCA-5′

Question 15

Which of the following events occurs during the termination phase of translation?

Accepted Answer

A stop codon is recognized and a release factor binds to the A site.

Question 16

A scientist mutates the TATA box in a eukaryotic promoter. What is the most likely effect on transcription?

Accepted Answer

Transcription factors will not bind properly, reducing transcription initiation.

Question 17

Which of the following best describes the difference between prokaryotic and eukaryotic gene expression?

Accepted Answer

In eukaryotes, RNA processing occurs before translation.

Question 18

If a eukaryotic cell fails to add a poly-A tail to its mRNA, what is the most likely consequence?

Accepted Answer

The mRNA will be more susceptible to degradation.

Question 19

Which of the following is true regarding the directionality of transcription?

Accepted Answer

RNA is synthesized in the 5′ to 3′ direction.

Question 20

A patient has a mutation that prevents the removal of introns from pre-mRNA. What is the most likely result?

Accepted Answer

The mature mRNA will contain non-coding sequences, possibly resulting in a nonfunctional protein.

Gene Expression: From Gene to Protein – Transcription and Translation

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