Question

Choose the correct statements :

(i) Polycistronic mRNA is generally found in eukaryotes.

(ii) The RNA polymerase II transcribes precursor of mRNA, the hnRNA.

(iii) The process of translation of mRNA begins when the mRNA encounters the large subunit of ribosomes.

(iv) Stop codons do not have any tRNAs.

• A. (i) and (ii)
• B. (ii) and (iii)
• C. (ii) and (iv)
• D. (i), (ii) and (iv)

Hint:

Polycistronic mRNA is prokaryotic and translation starts at the small subunit, so only (ii) and (iv) are true.

Answer 1

The Correct Option is C

Step 1: Check statement (i):
A polycistronic mRNA carries the code for more than one polypeptide. Such mRNA is found in bacteria (prokaryotes).
Eukaryotic mRNA is monocistronic. So (i) is FALSE.

Step 2: Check statement (ii):
In eukaryotes RNA polymerase II makes the precursor of mRNA, called hnRNA (heterogeneous nuclear RNA). It is then processed. So (ii) is TRUE.

Step 3: Check statement (iii):
Translation starts when the mRNA binds to the small subunit of the ribosome. The large subunit joins after the initiator tRNA is in place.
So (iii) is FALSE.

Step 4: Check statement (iv):
The stop codons UAA, UAG and UGA do not code for any amino acid, and no tRNA matches them. Release factors read them instead. So (iv) is TRUE.

Step 5: Choose the option:
Only (ii) and (iv) are correct. This is option (C). Options (A), (B) and (D) each contain a false statement.

Final Answer:
Statements (ii) and (iv) are correct, so the answer is option (C).