Biology - DNA replication help please?

Hi, so i was reading the CGP AQA textbook and it says that 'the active site of DNA polymerase is only complementary to the 3' end of the newly forming DNA strand - so the enzyme can only add nucleotides to the new strand at the 3' end. This means that the new strand is made in a 5' to 3' direction and that DNA polymerase moves down the template strand in a 3' to 5' direction'
Shouldn't it say that DNA polymerase is complementary to the 3' end of the template strand? If i'm wrong, then could someone explain it to me please? Thank you :smile:

Reply 1

TSR Jessica

19

Sorry you've not had any responses about this. :frown:

Are you sure you've posted in the right place? :smile:

Here's a link to our subject forum which should help get you more responses if you post there. :redface:

You can also find the Exam Thread list for A-levels here and GCSE here. :dumbells:

Just quoting in Puddles the Monkey so she can move the thread if needed :h:

Spoiler

Reply 2

Asklepios

19

Original post by Jade Li

Hi, so i was reading the CGP AQA textbook and it says that 'the active site of DNA polymerase is only complementary to the 3' end of the newly forming DNA strand - so the enzyme can only add nucleotides to the new strand at the 3' end. This means that the new strand is made in a 5' to 3' direction and that DNA polymerase moves down the template strand in a 3' to 5' direction'
Shouldn't it say that DNA polymerase is complementary to the 3' end of the template strand? If i'm wrong, then could someone explain it to me please? Thank you :smile:

The active site is where the substrates bind. In the case of DNA polymerase, the substrates are the free 3' end and free nucleotide.

Yes the polymerase molecule also has other domains which facilitate translocation along the DNA strand, but don't worry about that for A-level.

Biology - DNA replication help please?

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