Question 1

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

Accepted Answer

Multiple codons can code for the same amino acid.

Question 2

A mutation changes the DNA sequence from GAA to GTA in the gene encoding hemoglobin. What is the consequence of this mutation at the protein level?

Accepted Answer

A missense mutation occurs, resulting in valine replacing glutamic acid.

Question 3

Which of the following statements about the wobble position in tRNA is correct?

Accepted Answer

The wobble position allows tRNA to recognize multiple codons due to flexible base pairing at the third position.

Question 4

In the context of codon usage bias, which organism shows the highest preference for the CGU codon for arginine?

Accepted Answer

E. coli

Question 5

Which of the following best describes the difference between monocistronic and polycistronic mRNA?

Accepted Answer

Monocistronic mRNA encodes a single polypeptide, while polycistronic mRNA encodes several polypeptides.

Question 6

Which of the following is the correct sequence of events during translation initiation in eukaryotes?

Accepted Answer

Initiator tRNA binds to the small ribosomal subunit, then mRNA binds, then the large subunit joins

Question 7

Which of the following is NOT a posttranslational modification commonly found in proteins?

Accepted Answer

Replication

Question 8

A polyribosome (polysome) is best described as:

Accepted Answer

A cluster of ribosomes simultaneously translating the same mRNA molecule.

Question 9

Which of the following equations correctly represents the number of possible codons in the triplet genetic code?

Accepted Answer

$$4 	imes 4 	imes 4 = 64$$

Question 10

During translation elongation, which site on the ribosome is responsible for peptide bond formation?

Accepted Answer

P site

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 hydrolysis.

Question 12

Which of the following mutations would most likely result in a truncated, nonfunctional protein?

Accepted Answer

Nonsense mutation

Question 13

If a ribosome initiates translation at the wrong reading frame, what is the most likely outcome?

Accepted Answer

A completely different polypeptide sequence will be produced.

Question 14

Which of the following is true regarding the energy requirements for polypeptide elongation?

Accepted Answer

Elongation involves hydrolysis of at least four high-energy phosphoanhydride bonds per amino acid added.

Question 15

Which of the following is a function of the 5' cap and 3' poly(A) tail in eukaryotic mRNA?

Accepted Answer

They stabilize the mRNA and facilitate translation initiation.

Question 16

Which of the following best describes the fate of eukaryotic mRNA lacking a stop codon?

Accepted Answer

The ribosome stalls and an RNA-degrading enzyme degrades the defective mRNA.

Question 17

Which of the following is a real-world example of a missense mutation causing disease?

Accepted Answer

A mutation in hemoglobin leading to sickle-cell anemia.

Question 18

Which of the following is true about the universality of the genetic code?

Accepted Answer

The genetic code is nearly universal, with some exceptions in mitochondria and certain bacteria.

Question 19

Which of the following best describes the role of molecular chaperones in protein synthesis?

Accepted Answer

They facilitate proper folding of polypeptides and repair misfolded proteins.

Question 20

Which of the following is a consequence of codon usage bias in biotechnology applications?

Accepted Answer

It can affect the efficiency of protein production in recombinant organisms.

Gene Expression II: The Genetic Code and Protein Synthesis (Translation)

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