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DNA replication - DNA polymerase and ligase

I am confused about the two enzymes polymerase and ligase.

So, which one of them join nucleotides together, create the phosphodiester bond, link together two DNA strands, and other actions involved in DNA replication? Do they have other roles in DNA replication?

And are these actions from the 3` direction to the 5` direction or the other way round?

Somehow, I think the Edexcel textbook is quite unclear.. and as a private candidate, I turned to google some information, but there are quite a lot of confusing versions of the information of the two enzymes :s
so i really need some help :frown:
Thank you!
Original post by kesun
I am confused about the two enzymes polymerase and ligase.

So, which one of them join nucleotides together, create the phosphodiester bond, link together two DNA strands, and other actions involved in DNA replication? Do they have other roles in DNA replication?

And are these actions from the 3` direction to the 5` direction or the other way round?

Somehow, I think the Edexcel textbook is quite unclear.. and as a private candidate, I turned to google some information, but there are quite a lot of confusing versions of the information of the two enzymes :s
so i really need some help :frown:
Thank you!

Well, to explain this, I hope you are familiar with the concept of Okazaki fragments and the process of replication in the lagging strand.
Well, once these fragments have bound, they are "sealed" in their place by a special type of ligase called DNA ligase, which makes a phosphodiester bond between the adjacent fragments.

Polymerase is an enzyme used mostly in replication (DNA polymerase) and transcription (RNA polymerases). It will perform various functions. Just take one example of DNA polymerase 1. It has a forward (5'-3') activity adding nucelotides--this requires a primer. It has a reverse (3'-5') exonuclease proofreading activity.

I hope this helps :smile:
Reply 2
Avatar for kesun
kesun
OP
thank you for your help :wink:
and i found a video on youtube, http://www.youtube.com/watch?v=1L8Xb6j7A4w
which is quite helpful too :smile:
Original post by kesun
thank you for your help :wink:
and i found a video on youtube, http://www.youtube.com/watch?v=1L8Xb6j7A4w
which is quite helpful too :smile:

No problemo :smile:
That is good :smile:

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