Question

All of the following are involved in prokaryote protein synthesis except

• A. lntrons are removed from the mRNA transcript.
• B. RNA polymerase copies DNA into RNA nucleotides to produce mRNA
• C. Translation occurs simultaneously with transcription.
• D. Transcription and translation occur in the cytoplasm.
• E. All of the above events occur in prokaryote protein synthesis.

Answer 1

The correct option is A lntrons are removed from the mRNA transcript.

A. The primary transcript from a typical eukaryotic gene contains introns as well as exons. Exons are the coding regions whereas introns are non coding regions. Introns are removed from the primary transcript or pre mRNA by a process called RNA splicing.

B. RNA molecules are synthesised by an enzyme called RNA polymerase which uses a segment of a single strand of DNA as a template strand to produce a strand of RNA, complementary to base sequence to the template DNA. The RNA formed is messenger RNA or mRNA.

C. In prokaryotes, transcription and translation occur simultaneously in the cytoplasm because there is no nucleus in prokaryotes and as the RNA is produced from transcription, translation of RNA starts simultaneously.

D. Prokaryotes do not have a nucleus like eukaryotes where RNA is synthesised from transcription in the nucleus and then it is transported to the cytoplasm for translation. Hence both transcription and translation occur simultaneously in the cytoplasm in prokaryotes.

Hence, all the statements except statement A, hold true for the protein synthesis in prokaryotes.

So, the correct answer is 'lntrons are removed from the mRNA transcript'.