Question 1

Which of the following best describes the central dogma of molecular biology?

Accepted Answer

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

Question 2

A mutation in the gene encoding for an enzyme in a metabolic pathway prevents the synthesis of arginine in Neurospora. Which experimental result would support the 'one gene–one enzyme' hypothesis?

Accepted Answer

Each mutant strain is unable to grow on minimal medium unless supplemented with a specific intermediate or arginine.

Question 3

During transcription in eukaryotes, what is the role of the TATA box?

Accepted Answer

It is a promoter sequence that helps form the transcription initiation complex.

Question 4

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

Accepted Answer

The genetic code is redundant but not ambiguous.

Question 5

If a codon in mRNA is 5'-AUG-3', what amino acid does it code for?

Accepted Answer

Methionine

Question 6

What is the function of spliceosomes during RNA processing?

Accepted Answer

They remove introns and join exons in pre-mRNA.

Question 7

Which property of ribozymes challenged the previous belief about biological catalysts?

Accepted Answer

Ribozymes are RNA molecules that can catalyze reactions.

Question 8

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

Accepted Answer

Nonsense mutation

Question 9

Which of the following best explains why a single nucleotide substitution may not always result in a phenotypic change?

Accepted Answer

The genetic code is redundant, so some substitutions do not change the amino acid sequence.

Question 10

What is the main function of tRNA during translation?

Accepted Answer

To bring specific amino acids to the ribosome and match them to the mRNA codon.

Question 11

Which of the following is a consequence of alternative RNA splicing?

Accepted Answer

A single gene can code for multiple polypeptides.

Question 12

A frameshift mutation is most likely to result from which of the following?

Accepted Answer

An insertion or deletion of nucleotides not in multiples of three.

Question 13

Which of the following best describes the role of the signal-recognition particle (SRP) in protein targeting?

Accepted Answer

It directs the ribosome to the endoplasmic reticulum for protein synthesis.

Question 14

Which of the following is a post-translational modification that can alter protein function?

Accepted Answer

Phosphorylation

Question 15

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

Accepted Answer

There is no nuclear envelope separating the processes.

Question 16

Which of the following equations correctly represents the number of possible codons given four nucleotide bases and codons of length three?

Accepted Answer

$$4^3 = 64$

Question 17

A patient with sickle cell anemia has a mutation in the β-globin gene. What type of mutation is responsible for this disease?

Accepted Answer

Missense mutation

Question 18

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

Accepted Answer

The same codons specify the same amino acids in almost all organisms.

Question 19

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

Accepted Answer

They code for amino acids in the final protein.

Question 20

A scientist introduces a gene from a firefly into a plant, and the plant begins to glow. What does this experiment demonstrate about the genetic code?

Accepted Answer

The genetic code is universal and can be read by different species.

CH17 - Gene Expression: From DNA to Protein and Mutations

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