Circular DNA, RNA Genes and Viruses

[@quazisharminbonny368]

Your lectures are really really helpful.Love it.

[@lucasvcm]

I saw that in human's liver cells and yeast's cells also exists circular DNA, and they are both eucariotic. Where else can I find circular DNA, since being procariotic is not a rule?

[@day4640]

Thank you Andrey!!

[@oristo42_3]

Hello, I would love it if you display the board for first three seconds before the lecture starts. It is hard to write them down on my notes when your body is blocking half of the board. But, your videos helped me a lot. Thank you.

[@katdeng8587]

at step 3, you mentioned that newly formed cDNA strands are complimentary to each other, thus they could anneal together. How could they be complimentary to each other?

[@godslove7301]

Kat Deng the viral RNA strands are complementary and so when Reverse transcriptase enzyme transcribes both strands the DNA transcripts complementary as the RNA strands where they were transcribed from are complementary.

[@bark.2122]

2 copies of viral RNA.. as I understand, copies mean they have the same sequence of nucleotides..but doesn't mean they are complementary... being the case, they cannot anneal.....so how the 2 single strands of the viral DNA are annealed ? Thank you ❤️.

[@Procrastinerd]

Does helicase separate the blue, reverse-transcribed strand shown in Step 3 of the diagram?

[@AKLECTURES]

Silent Language Helicase s a general name for the group of enzymes that catalyze the unwinding of DNA or RNA molecules. DNA helicases unwind DNA and RNA helicases unwind RNA. So my bet is yes, a type of helicase unwinds that hybrid molecule.

[@Procrastinerd]

AK LECTURES Thanks. The quality of your lectures is top-tier.

[@AKLECTURES]

Silent Language Thank you :-) takes a lot of work so I appreciate that!

[@abhinavbanerjee9649]

The case of reverse transcription is unique. The reverse transcriptase enzyme has an RNase H activity that specifically cleaves RNA in a RNA-DNA hybrid. The protein manages to first, form the cDNA of the viral RNA and then cleave the RNA at places so that DNA polymerase can actually fill the gaps and form the double stranded viral DNA that is then integrated into the host genome. It is also known that due to catalytic isolation between the RNA polymerase active site and the RNase H active site, the protein flips in orientation to perform either of the functions, thus binding in two unique orientations onto the RNA-DNA hybrid.

[@casualcasual1234]

@@abhinavbanerjee9649 To confirm, may I ask can I say that after reverse transcription is done, the reverse transcriptase can simply flip and expose the RNase H domain and bind to the viral mRNA and cleave it?

[@junczhang]

thanks!

[@farhanaifnt9670]

Retrovirus is able to replicate because of reverse transcriptase enzyme, right? so where the enzyme come from? is it from the virus or from the host cell?

[@AKLECTURES]

Nur Farhana New viruses that are being synthesized inside the host cell use that cells machinery to synthesize new enzymes, including reverse transcriptase.

[@day4640]

+AK LECTURES (Andrey K) so we dont have in our normal cells the ''reverse transcriptase? sooooo if this is like this, the pharmaceutic industry why the hell dont focus on destroying this f* enzyme!!! Pharmaceutic Mafia!!

[@drvir]

Are you guys talking about my reverse transcription? Aww I am so famous!

[@abhinavbanerjee9649]

The enzyme is surprisingly carried inside the viral capsid. Both the reverse transcriptase enzyme and the integrase enzyme are carried within the viral capsid. The virus isn't dependent on the host to perform the action but my best guess is that the reverse transcriptase enzyme is activated only after fusion of the HIV particle to its host cell. The reverse transcriptase for new virus particles are then made within the host cell from mRNAs generated from the integrated viral genome.

[@ApteraEV2024]

Again, 7yrs late to the Party....better late than never....((