Roxanita
Forum Senior
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Q.- Topoisomerases are a class of enzymes involved in:
a) DNA transcription and replication.
b) Translation of mRNA.
c) Splicing of mRNA.
d) Proofreading of DNA during replication
e) Exising mismatched base pairs during DNA repair.
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| Idiopathic
Forum Guru
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Topoisomerases are responsible for nicking DNA during transcription/translation, in order to avoid supercoiling, correct? (A)
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| suvi21
Forum Junior
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A; however I'm not quite sure about its role in transcription :roll:
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| rida
Forum Guru
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A definetely, idiopathic, according to kaplan, they are involved in transcription and replication, are you sure also in translation??
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| Roxanita
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Very good guys 
Rp: a)
Topoisomerase is a class of enzyme that is critical to the normal function of living cells. They are involved in unwinding the DNA to allow transcription and replication to occur.
The DNA topology is adjusted by making temporary cuts in the DNA which allows unwinding of the DNA; this makes it possible for the transcription and replication enzyme complexes to function by moving down the DNA strand. Normally, these cuts are then re-ligated.
A group of Anti-tumor chemotherapy compounds such as: Camptothecin and Topotecan, target Topoisomerases. These inhibitors lock the Enzyme DNA-Complex at the stage after the cut is made and before the DNA is ligated. This prevents the DNA and Topoisomerase from continuing in the Replication or Transcription pathway.
Camptothecin is an alkaloid and is the first known naturally produced inhibitor of DNA topoisomerase I; it is used in the treatment of a wide variety of cancers.
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"We all basically have 2 choices in life: Let things stay the way they are or work to make them better"
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| suvi21
Forum Junior
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Sorry, I also meant not sure in translation (don't see their need)???
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