Clozapine
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Hepadna virus carries~
a) DNA dependent RNA polymerase
b) DNA dependent DNA polymerase
c) RNA dependent RNA polymerase
d) RNA dependent DNA polymerase
dont forget to explain.
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| Ancylostoma
Forum Guru
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D. Rna dependent DNa Polymerase. I think its because it sometimes concverts it rna back into dna to create provirus and incorporate into our DNA. This occurs in people who are infected early and become chronic carriers. I know the answer because my friend who took the test at the end of the year got this exact question but instead they asked which virus had a rna dept Dna polymerase. It is a real question guys , memorize it !!
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| Clozapine
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correct. but u might wanna double check the explanation  since it`s HY
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| Ancylostoma
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Yeah I was guessing on the explanation. I cant remember it but I dont really feel like searching and since you know it. Tell me
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| ashfaque
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but its dna dependent dna polymerase as mentioned in first aid so answer should b B
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| Nan
Forum Senior
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Agree. B. See FA. p157
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| Ancylostoma
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how can a reverse transcriptase be a dna dependent polymerase? That just doesnt make anysense to me. If Fa says so its a typo. check this site and you will see Why. http://medgadget.com/archives/2006/06/taking_a_cl...
There is another post if you look through my post history , where clozapine explains it extremely well.
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| residency_2008
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the answer is D RNA dependent DNA poly....it replicates through rna intermediate.
this must be mugged up. this 1 is tricky
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| darkhorse
Forum Elite
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i m not sure guys...it has both rna and dna dependent dna polymerase...see this link
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd...
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| Clozapine
Forum Elite
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Hey guys .... I found this piece of info in Kaplan micro and then tried to get a grasp of the HBV replication from levinson micro review, everywhere they said HBV has an RNA dependent DNA Polymerase .... i also explained what I learnt here
Anyways, just now I did a lil reaseach and I`m totally confused now .... this is from Harrison
HBV is unique because virion DNA expression in infected cells results in the packaging of reverse transcriptase and genomic RNA in the virion. The genomic RNA is then copied into an incomplete double-strand circular DNA genome before the virion matures and is released from the infected cell. On entry of HBV into the cytoplasm of an infected cell, the virion reverse transcriptase/DNA polymerase completes DNA synthesis, and the covalently closed circular genome resides in the nucleus. Viral mRNAs are transcribed from the closed circular viral episome by cellular RNA polymerase II. A capped and polyadenylated, full-genome-length, terminally redundant transcript is packaged into virus core particles in the cytoplasm of infected cells. This RNA associates with the viral reverse transcriptase. The reverse transcriptase converts the full-length, terminally redundant, core-particle, encapsidated RNA genome into partially double-strand DNA. HBV is believed to mature by budding through the cell's plasma membrane, which has been modified by the insertion of viral surface antigen protein.
someone rescue me
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| babydoc4usmle
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it's all too much, but if you delete scientific abra-kadabra you'll see at the end:
partially dsDNA virus-->RNA-->dsDNA
first step is to make mRNA and second is completed by RNA-dep-DNA-polymerase, which has this name per se in Retrovirus (HIV), but in HBV it named DNA polymerase, which still does the same thing: makes 1 strand DNA using mRNA as a template and then completes DNA by duplicating single strand DNA
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| Clozapine
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Thanks babydoc, I think I know how it works but I guess I got confused when I saw it`s also called reverse transcriptase since I cooked the q up .... I thought i even saw a table or something in levinson where they identified the diff. b/w Reverse Transcriptase and HBV RNA-dep DNA polymerase.. anyways
I guess for all practical purpose  it`s RNA dep DNA polymerase ...
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| sixfeet
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i think i've a clue... hiv and hbv boh 've rev transcriptases.. latter is early actin and synthesis dna from genome rna which integrates wid host genome.. hbv on the other hand has a late actin RT, which is synthesises the dna genome from rna intermediate.. it also has a dna dependent dna pol for fillin in the missin portion of dna.. and this one acts early on at the beginin of replictn..
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| shalini.ravi
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so is d the ans ?
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| lq2006
Forum Elite
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Yes, RNA dependent DNA polymerase
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| SmokyWaters
Forum Elite
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I dunno what the answer is but the SAME enzyme carries both RNA dep DNA pol activity as well as DNA dep DNA pol activity as far as I remember...although the SECOND action is RNA dependent DNA pol activity resulting in formation of mRNA....in cytoplasm from partial double staranded closed circular DNA ...DNA dependent DNA pol activity is the FIRST that occurs
but again there is DNA dependent activity that fills in the missing portion of DNA soon after infection of the next cell is carried out ....that occurs in the nuclear
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