PowerPoint Presentation On RNA Polymerase Enzyme

PPT On RNA Polymerase Enzyme

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RNA Polymerase Enzyme Presentation Transcript:

1. 1. The DNA replicates its information in a process that involves many enzymes: replication. 2. The DNA codes for the production of messenger RNA (mRNA) during transcription. 3. In eucaryotic cells, the mRNA is processed (essentially by splicing) and migrates from the nucleus to the cytoplasm. 4. Messenger RNA carries coded information to ribosomes. The ribosomes "read" this information and use it for protein synthesis. This process is called translation. Proteins do not code for the production of protein, RNA or DNA. They are involved in almost all biological activities, structural or enzymatic.

2. Transcription
Transcription is the process by which a single stranded RNA is formed from a single strand of DNA. The process involves : Uncoiling of the 2 strands of DNA in a specific region. It exposes the bases of the DNA strands. One strand of DNA remains dormant & the other one acts as the template for the formation of the new RNA strand. The building blocks the free nucleotides align themselves & form the complementary RNA according to the base pairing rule. The reaction is catalyzed by the enzyme RNA Polymerase. RNA polymerase catalyzes the formation of phosphodiesterase bonds between nucleotides (using tri-phosphate nucleotides). RNA polymerase moves stepwise along the DNA extending the RNA chain as it goes. As RNA polymerase moves it unwinds the next part of the helix, the helix behind closes & the mRNA is displaced

3. RNA polymerase
(RNAP or RNApol) is an enzyme that makes a RNA copy of a DNA or RNA template. In cells, RNAP is needed for constructing RNA chains from DNA genes, a process called transcription. RNA polymerase enzymes are essential to life and are found in all organisms and many viruses. In chemical terms, RNAP is a nucleotidyl transferase that polymerizes ribonucleotides at the 3' end of an RNA transcript.

4. History RNA Polymerase
or RNAP was discovered independently by Sam Weiss & Jerard Hurwitz in 1960. In 2006, the Nobel Prize in Chemistry was awarded to Roger Kornberg for creating detailed molecular images of RNA polymerase during various stages of transcription.

5. Structure Of RNA Polymerase
RNA polymerase in Prokaryotes (Bacteria) : In bacteria, the same enzyme catalyzes the synthesis of mRNA RNAP is a relatively large molecule. The core enzyme has 5 subunits (~400 kDa):α2: the two α subunits assemble the enzyme and recognize regulatory factors. Each subunit has two domains: αCTD (C-Terminal domain) binds the UP element of the extended promoter, and αNTD (N-terminal domain) binds the rest of the polymerase. β: this has the polymerase activity (catalyzes the synthesis of RNA) which includes chain initiation and elongation. β': binds to DNA (nonspecifically). ω: restores denatured RNA polymerase to its functional form in vitro.

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