function of polymerase and neuclease

[wasifa]

please inform the function of polymerase and neuclease. why there is mismatces in dna coding if there is uracil in dna?

[thedarkshade]

please inform the function of polymerase and neuclease. why there is mismatces in dna coding if there is uracil in dna?

Polymerase and nuclease are some of the key substances in the replication process, where some other key substances are helicase, topoisomerase, endonucleaze and ekzonuclease. Nuclease breaks apart the hydrogen bonds existing between nitrogen bases (A T G C). Within nuclease there is a very important protein (SSB) which makes impossible for the nucleotid chains to come together again and forming so the "DNA fork". Topoisomerase eliminates the spiral shape of DNA. Endonucleases and ekzonucleases break phosphodiester bonds, endo from the inside and ekzo form the outside. And polymerase adds complementary bases to the two semi-conservativ chains formed as a result of replication.

 

And BTW, DNA does not have uracil, it has thymine instead. RNA does have uracil, and the difference between thymine and uracil (IIRC) stands in a methil group, I'm not sure though. Some bio-expert could help here!

[ecoli]

Cytosine spontaneously deaminates into uracil, so that's the main reason why DNA contains thymine instead. That way, you can be sure that any uracil incorporated into DNA is a mistake. This is fixed via the base excision repair (BER) mechanism.

 

Just to add onto what darkshade said, in english (I know you're not a native speaker) it's exonuclease (as opposed to ekzo-).

 

Also, there are many different types of polymerases and nucleases, so you'll have to be more specific.

[thedarkshade]

Just to add onto what darkshade said, in english (I know you're not a native speaker) it's exonuclease (as opposed to ekzo-).

I got that red underlining all the time but I simply ignored it. Not that I had no time but just didn't try to get the right word.

 

Thanks for correcting;)

 

edit: there is another identical thread here by the same user but with 0 replies. Some mod please delete it!