abitpissy
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#1
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#1
Kind of confused, here in my textbook it says DNA polymerase assemble nucleotides from the 5' -3' direction.

I don't understand how that could happen if DNA Polymerase can only attach in the 3' because of the hydroxyl group.

So surely it would move along the strand, where it initially attached from the 3'-5' attaching nucleotides?
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alkyone
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So polymerase binds to the 5' end. And it moves towards the 3' end. If we say for the sake of this explanation that 5' is left and 3' is right... It is moving from left to right but can only add nucleotides to the right side of the strand.
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abitpissy
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(Original post by alkyone)
So polymerase binds to the 5' end. And it moves towards the 3' end. If we say for the sake of this explanation that 5' is left and 3' is right... It is moving from left to right but can only add nucleotides to the right side of the strand.
Right so it attaches at the 5' and not the 3'?
( so where does the hydroxyl group come in?)
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Muz_333
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Quick google illustrates this better than I can.

https://en.wikipedia.org/wiki/FileNA_polymerase.svg

The polymerase, as explained above, moves left to right. As in 5' to 3'.
However the nucleotides are added at the 3' end of the polymerase then the polymerase travels past this.

Edit:
Basically, think of the end on the right of the polymerase as the 3' where it actively adding bases while chugging along. So while it's moving from the 5' to the 3', the right of the polymerase is always considered the the 3' end, where the bases are added.
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abitpissy
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(Original post by Muz_333)
Quick google illustrates this better than I can.

https://en.wikipedia.org/wiki/FileNA_polymerase.svg

The polymerase, as explained above, moves left to right. As in 5' to 3'.
However the nucleotides are added at the 3' end of the polymerase then the polymerase travels past this.

Ohh okay, so it attached at the 3' and just traveled by it. It starts to assemble nucleotides from the 5' end towards the 3'?
Thanks
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Muz_333
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(Original post by Questioness)
Ohh okay, so it attached at the 3' and just traveled by it. It starts to assemble nucleotides from the 5' end towards the 3'?
Thanks
Yup, thankfully even in my drunken state you understand what I'm trying to say.

The polymerase is always travelling 5' to 3' while adding the bases to the end of the strand, which is the 3'.
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Gambit_RD2B_GR
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Hello, In order to understand better how it adds nucleotides in the growing strand try and visualize the enzyme as a zipper that pries open in half the growing strand and walks on the dna template while adding nucleotides in the complementary bases along the '3 growing strand which is always from left to right.

Have a look at this below to visualize the process. Good luck on your exams!

http://sites.fas.harvard.edu/~biotex...plication1.swf
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