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led0zeppelin1977 (November 30, 1999 at 12:00 am)
its got guidance, once there is an input of atp, its all really guided by relative charge and steric hindrance
nurbsenvi (November 30, 1999 at 12:00 am)
How the hell does this happen without some sort of guidance? that's insane.
micoantonio (November 30, 1999 at 12:00 am)
THANKS. Now I get it
xEternalx (November 30, 1999 at 12:00 am)
Hey ForeverADreamer89, thanks. it helped.
ForeverADreamer89 (November 30, 1999 at 12:00 am)
Hope this helps:)
ForeverADreamer89 (November 30, 1999 at 12:00 am)
The leading strand of DNA is made up of nucleic acids arranged in the 5' to 3' direction (phosphate group to hydroxyl of another nucleic acid). The lagging strand runs in the opposite direction because it runs parallel and is made up of bases (A,T,G,C) opposite to those on the leading strand. The enzyme DNA polymerase only works in the 5' to 3' direction, and so has trouble working on the lagging strand, which runs in the 3' to 5" direction & needs RNA primase to add many primers to guide it.
ForeverADreamer89 (November 30, 1999 at 12:00 am)
On the leading strand, only one sequence of RNA primers has to be installed so DNA polymerase to join onto it and then continually synthesize an entire new strand of DNA, working in the 5' to 3' direction. The lagging strand is of course arranged in the 3' to 5' direction, and so in order for DNA polymerase enzyme to work, many RNA primer sequences need to be installed to guide it's action, resulting in lots of little new DNA sections that need to be joined later (Okazaki fragments).
xEternalx (November 30, 1999 at 12:00 am)
Another question, why does the primase have to install RNA segments in different parts of the lagging strand as shown in the video. (the RNA segment were represented with green colour strands)?
xEternalx (November 30, 1999 at 12:00 am)
do you know why the lagging strand imposes a problem during transcription and that an RNA primase has to be used ?
ForeverADreamer89 (November 30, 1999 at 12:00 am)
The 5' end of the nucleotide is the phosphate group (something to do with the arrangement of carbons), the 3' end of the nucleotide is on the other side where the hydorxyl group is (in other words, nucleotides link up via a phosphate joining a hydroxyl of another nucleotide in the chain).
Don't worry, that stumped me for years, until half way through my first year of a medical degree actually! |
