DNA Topoismomerase

[adrakdavra]

Advertisement - Members don't see this ad

Hi, Do we have to know about the DNA Topoisomerase Fuction for the MCAT? and what does Topo isomer ase means ?

 

[Saint Fu]

It's probably better to know it, and it's not too complicated. It's basically an enzyme that helps prevent the overwinding of DNA during DNA replication. I don't think you'll have to know the molecular details of how it works.

 

[rjosh33]

Yep, what Saint Fu said. Although topoisomerases function during transcription as well.

 

[mcloaf]

It's quite straightforward; as DNA is pulled apart the part of the helix ahead of the replication fork is subject to increased tension (i.e. for every twist pulled out at the fork, the DNA ahead of the fork has another twist forced into it). At some point the DNA begin to supercoil and you can't unwind it anymore because the tension is too high. Topoisomerase (also called DNA gyrase, though I'm not sure if/what the difference is) simply relieves this tension by cutting a strand of DNA, unwinding a twist in the DNA, and then ligating it back together. There are videos on youtube if you're interested.