00:01
You're provided with a purified sample of circular plasmid, which has been determined to have exactly two cut sites for enzyme ecor1.
00:11
Now you digested the plasmid with ecor1 and analyzed 10 nanograms of cut or uncut dna.
00:19
So as you can see, u stands for uncut dna and d stands for the cut or digested dna.
00:27
And then you go through agarose gel electrophoresis.
00:31
And then on the right side of the gel, you have a dna ladder, which is right here.
00:37
So basically you see five bands.
00:40
Each band you know that the size corresponding to the position it runs on the gel.
00:46
So based on the simulated gel results show what is the length of the original uncut plasmid.
00:52
So you can see that uncut sample runs as 2000 base pair.
00:57
However, the undigested circular plasmid doesn't run as a circle in the gel.
01:06
Instead, it runs as a supercoil.
01:12
Basically it looks like this.
01:17
So then due to the shape of supercoil, the size of the plasmid will not be accurately reflected on the gel.
01:27
So the actual size of the plasmid is going to be bigger than 2000 base pair.
01:34
Because supercoil is the most stable structure, the circular dna is going to run in the gel.
01:43
So due to its conformation, its mobility or migration pattern is a little bit different from its original size...