Question

Transcription in prokaryotes

Answer 1

trancription is a process by which DNA is changed into RNA by DNA DEPENDENT RNA POLYMERASE..in eukaryotes trandcription occur in nucleus of cell bt in prokaryotes there is no nucleus therefore process occur in cytoplasm of cell..prokaryotes posses only 1 type of RNA polymerase which form all type of RNA..even prokaryotes also dont have mechanism of splicing..

Answer 2

ANSWER

✏ In prokaryotes such as bacteria there is a single DNA dependent, RNA polymerase that catalyses transcription of all types of RNA, mRNA, tRNA and rRNA.

✏ The process of transcription involves following steps;

I) INITIATION :-

✏ On specific signal the RNA polymerase binds to promote and initiates transcription.

✏ The promoter region in a cistron is recognised by sigma subunit of the RNA polymerase in prokaryotes and many transcription factors in eukaryotes.

II) ELONGATION :-

✏ The RNA polymerase uses ribonucleoside triphosphate as substrates and polymerase in a template dependent manner following the rule of complementarity.

✏ RNA polymerase moves along the transcription unit and causes unwinding and opening the helix and continuous elongation of RNA.

✏ The sigma factor of the RNA polymerase separate on the initiation of RNA chain.

✏ The remaining part of the RNA polymerase referred as core enzyme moves along the DNA template causing elongation of RNA chain at the rate of 30 nucleotides per seconds.

✏ Elongation takes place in 5’ – 3’ direction.

III) TERMINATION :-

✏ One the RNA poly merase reaches to the terminator the RNA fall off and also the enzymes.

✏ Termination factor P factor (rho) is required for RNA chain.