Question

Which of the following statements are correct regarding protein synthesis in eukaryotes?
A. 3'-Cap of mRNA present.
B. Ribosomes of 80S type dissociate into 40S and 60S subunits.
C. Translation is not simultaneous with transcription.
D. Initiation codon of mRNA is recognised by anticodon of Met-tRNA.
Choose the correct answer from the options given below:

• A. A, C and D only
• B. A, B and C only
• C. B, C and D only
• D. A, B, C, D

Hint:

Remember the key differences between prokaryotic and eukaryotic protein synthesis: \textbf{Eukaryotes:} 80S ribosomes (60S+40S), 5' cap & 3' tail, monocistronic mRNA, transcription in nucleus, translation in cytoplasm (separate), initiator is Met-tRNA. \textbf{Prokaryotes:} 70S ribosomes (50S+30S), no cap/tail, polycistronic mRNA, transcription and translation are coupled, initiator is fMet-tRNA.

Answer 1

The Correct Option is C

Step 1: Concept Overview:
The question requires identifying accurate statements regarding eukaryotic protein synthesis (translation). This necessitates understanding the key differences between eukaryotic and prokaryotic translation.
Step 2: Detailed Analysis:
Evaluation of each statement follows:

A. 3'-Cap of mRNA present. This is incorrect. Eukaryotic mRNA undergoes post-transcriptional modification, including a 7-methylguanosine cap added to the 5' end, not the 3' end. The 3' end typically features a poly-A tail.

B. Ribosomes of 80S type dissociate into 40S and 60S subunits. This is correct. Eukaryotic cells possess 80S ribosomes, composed of 40S and 60S subunits. (Svedberg units are not additive).

C. Translation is not simultaneous with transcription. This is correct. In eukaryotes, transcription occurs in the nucleus, and translation in the cytoplasm. This spatial and temporal separation (and mRNA processing requirements) prevents coupling of the two processes, unlike in prokaryotes where they occur concurrently in the cytoplasm.

D. Initiation codon of mRNA is recognised by anticodon of Met-tRNA. This is correct. The eukaryotic start codon, AUG, is recognized by the anticodon of a special initiator tRNA carrying Methionine (Met).

Step 3: Conclusion:
Statements B, C, and D are correct; statement A is incorrect. Therefore, the correct answer is the option including only B, C, and D.