Question

There are three (3) types of RNA in prokaryotic cells. What are the types and how are these molecules synthesized? Compare and contrast RNA synthesis in prokaryotes to that of eukaryotes.

Answer 1

The tree types of RNA

Messenger RNA (mRNA )which  encodes amino acid sequence of a polypeptide.

Transfer RNA (tRNA ) responsible for bringing amino acids to add to the growing polypeptide.

Ribosomal RNA (rRNA ) Structural components of ribosomes

These molecules are synthesized by the Prokaryotic RNA polymerase through the process of transcription. Prokaryotic polymerase is a multi-sub unit protein having two α sub units , a β and a β′ sub unit and a σ sub unit altogether forming a core enzyme.

In eukaryotes RNA synthesis or transcription is achieved by 3 types of RNA polymerases. RNA pol I transcribes rRNAs RNA pol II transcribes mRNAs and RNA pol III transcribes tRNA, 5srRNA and few other non coding RNAs. And in eukaryotes mRNA is transcribed as a premature RNA which undergoes 5' capping , addition of poly A tail as well as intron removal to form a mature mRNA. This post transcriptional modification is not there in prokaryotes.