Wednesday, March 7, 2012

What constitutes the leading strand in DNA replication?

My actual question is this: If you block DNA Ligase in E. Coli, then will synthesis of the leading strand still be completed? My contention is that no, it is not, because the RNA primer that was layed down to start that synthesis will not be ligated to the rest of the strand, so there will be a short fragment there in the leading strand. What do you think?What constitutes the leading strand in DNA replication?
DNA ligase is only active on the LAGGING strand, in order to connect the Okazuki fragments. The leading strand, going from 5' to 3', is produced in one long strand (mRNA, section by section when the appropriate replication forks are open.

If you block DNA ligase, you only affect the Lagging strand, so your contention is false. However, you will disrupt translation, because the the 3' to 5' strand will not be completed. Since DNA is conserved (1 strand of old, 1 strand of new, for EACH organism), you will still be able to make 1 set (just not both).What constitutes the leading strand in DNA replication?
But you make no mention of my specific issue. There will be ONE gap one the leading strand, where the initial primer meets the rest of the leading strand. The question concerns whether that one gap constitutes an incomplete strand, which you have not addressed.

Report Abuse

No comments:

Post a Comment