Question

1. Describe the action of RNA polymerase inside a cell. Could a RNA virus use a human host cell’s RNA polymerase to make copies of viral RNA from a viral RNA template? Why or why not?

Answer 1

A. RNA Polymerase: It is a enzyme which engagged in the process of transcription where the RNA is synthesized from the DNA template.

The action of the RNA Polymerase is divided in three phases-

• Initiation: After binding to the DNA, the RNA polymerase switches from a closed complicated to an open complex. This change entails the separation of the DNA strands to shape an unwound segment of DNA of about 13 bp, known as the "transcription bubble". Supercoiling performs an crucial component in polymerase interest due to the unwinding and rewinding of DNA. Because regions of DNA in the front of RNAP are unwound, there are compensatory superb supercoils. Regions at the back of RNAP are rewound and bad supercoils are present.
• Elongation: The 17-bp transcriptional complicated has an 8-bp DNA-RNA hybrid, that is, eight base-pairs involve the RNA transcript sure to the DNA template strand.As transcription progresses, ribonucleotides are introduced to the 3' stop of the RNA transcript and the RNAP complicated actions along the DNA. The feature elongation prices in prokaryotes and eukaryotes are about 10–100 neucleotides/sec.
• Termination: Termination of RNA transcription can be rho-established or rho-impartial. The former is based at the rho issue, which destablizes the DNA-RNA heteroduplex and reasons RNA release.[20] The latter, additionally referred to as intrinsic termination, is based on a palindromic region of DNA. Transcribing the vicinity reasons the formation of a "hairpin" shape from the RNA transcription looping and binding upon itself. This hairpin structure is regularly rich in G-C base-pairs, making it greater solid than the DNA-RNA hybrid itself. As a end result, the eight bp DNA-RNA hybrid inside the transcription complex shifts to a 4 bp hybrid. These ultimate 4 base pairs are weak A-U base pairs, and the complete RNA transcript will fall off the DNA.

B. No the RNA virus does not use the host cell RNA polymerase.

The RNA virus genome carry its own PNA polymerase in its genome,because the host RNA polymerase enzyme can not transcript the dsRNA (virus RNA gemone) as the mRNA.So the virus carry its own RNA Polymerase which is present inside the viral capsid to synthesize mRNA and replicate its genome.