Quiz: Genetic Translation and Protein Synthesis — 10 questions

1. What is the role of RNA polymerase during gene expression?

A. It reads stop codons and ends translation

B. It carries amino acids to the ribosome

C. It folds the new polypeptide into its final shape

D. It synthesizes mRNA during transcription

Answer: (D)

Explanation

RNA polymerase is the enzyme that builds mRNA in transcription. tRNA carries amino acids, and stop-codon recognition belongs to translation, not RNA polymerase.

2. What is transcription?

A. The release of a polypeptide at a stop codon

B. The conversion of protein into RNA

C. The pairing of anticodons with amino acids

D. The nuclear synthesis of mRNA from a DNA template strand

Answer: (D)

Explanation

Transcription is the nuclear step that produces mRNA from a DNA template strand. The other options describe translation or unrelated processes.

3. What happens during translation initiation?

A. Peptide bonds stop forming

B. The ribosome begins at the start codon on mRNA

C. The polypeptide is released at a stop codon

D. The protein folds before the ribosome binds

Answer: (B)

Explanation

Initiation is the start of translation at the start codon, which is AUG. Termination and folding occur later, not at initiation.

4. How do polyribosomes increase protein production?

A. By stopping translation after the first peptide bond

B. By allowing multiple ribosomes to translate the same mRNA at the same time

C. By converting mRNA back into DNA

D. By making each ribosome read only one codon

Answer: (B)

Explanation

Polyribosomes are complexes of many ribosomes translating the same mRNA simultaneously, which boosts protein output. They do not reverse transcription or halt translation.

5. Which codon serves as the translation start codon and codes for methionine?

A. UGG

B. AUG

C. UAA

D. UAG

Answer: (B)

Explanation

AUG is the start codon and it codes methionine. UAA and UAG are stop codons, while UGG codes tryptophan.

6. What best describes a gene in relation to DNA?

A. A specific sequence of nucleotides located on a DNA molecule

B. A protein that stores hereditary information

C. A short RNA molecule that carries amino acids to the ribosome

D. A base found only in RNA molecules

Answer: (A)

Explanation

A gene is defined as a specific nucleotide sequence on DNA. The other choices describe RNA-related features or proteins, not genes.

7. What does a codon specify?

A. A ribose-containing sugar

B. An amino acid or a stop signal

C. A ribosome subunit

D. A DNA repair enzyme

Answer: (B)

Explanation

A codon is a triplet of bases on mRNA that specifies an amino acid or a stop signal. The other choices are unrelated to codons.

8. What is the main function of tRNA in translation?

A. To catalyze the folding of proteins after translation ends

B. To copy DNA into mRNA

C. To form the small ribosomal subunit

D. To match mRNA codons and deliver the corresponding amino acids

Answer: (D)

Explanation

tRNA uses its complementary anticodon to recognize mRNA codons and brings the matching amino acid. The other choices describe different molecules or processes.

9. Which feature distinguishes RNA from DNA in this material?

A. It is the nuclear support of inherited traits

B. It contains uracil and ribose

C. It is located only in the nucleus

D. It is made of deoxyribose and thymine

Answer: (B)

Explanation

RNA is described as containing ribose and uracil. DNA is the nuclear support of inherited traits, so the other choices describe DNA or are incorrect.

10. What occurs after translation terminates at a stop codon?

A. The polypeptide is released and folds into its three-dimensional structure

B. The mRNA is converted into DNA

C. The tRNA remains permanently attached to the ribosome

D. The ribosome adds another amino acid and continues

Answer: (A)

Explanation

When a stop codon is reached, the polypeptide is released and then folds into its functional three-dimensional form. Translation does not continue past a stop codon.