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Reverse transcription. Ahmed Yossre To Dr. Noha Khalifa. Agenda. Introduction Function in viruses The process of reverse transcription Steps of creating viral DNA How does Integrase enzyme works ?. Introduction. What is Reverse transcription ?
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Reverse transcription Ahmed Yossre To Dr. Noha Khalifa
Agenda • Introduction • Function in viruses • The process of reverse transcription • Steps of creating viral DNA • How does Integrase enzyme works ?
Introduction What is Reverse transcription ? The process of DNA transcription but in the opposite direction by the reverse transcriptase. It was discovered by Howard Temin & David Baltimore at the University of Wisconsin–Madison.
Function in Viruses • Viruses uses the enzyme to integrate their viral RNA into the host cell • Some viruses make thier RNA works as a DNA complementary strand
The process of reverse transcription • The genomes of retroviruses consists of 2 molecules of single strand RNA with a 5’Cap and 3’polyadenylated tail. • Ex. Of retroviruses: • HIV virus • HTLV virus: The process of creating a double-stranded viral DNA takes place in the cytosol in a series of steps:
Steps of creating a Viral DNA • Step I: • The tRNA hybridizes to a complementary part of the viral genome called “Primary Binding site” • Step II: • The complementary DNA then binds with the Non-coding regions and the R region of the viral RNA
Steps of creating a Viral DNA • Step III: • The RNAse H degrades the 5’ end of the RNA which removes the non-Coding and R regions. • Step IV: • The Primer starts synthesizing DNA from the 3’ end of the viral genome and adds it to the R-region of the RNA strand
Steps of creating a Viral DNA • Step V: • The cDNA is extended and the rest of majority of the viral RNA is degraded • Step VI: • After synthesizing the complete strand a new strand is being synthesized from the viral RNA
Steps of creating a Viral DNA • Step VII: • The Primer Binding Site of the first strand then jumbs to hybrid to the second Primer Binding Site. • Step VIII: • Both strands are then incorporated and integrated with the Integrase enzyme
How does Integrase works ? • 1st : It binds with the nucleus membrane and open a hole into it . • 2nd : It takes the new viral DNA and go with it into the nucleus. • With the help of other enzymes it binds the viral DNA with the DNA.
References • Wikipedia #1 • Wikipedia #2 • Aids.about.com • Bioproductsmd.com • Google.com
Thank You Ahmed Yossre
