00:03
So you're looking at a gel electrophoresis result and on lane one is the dna ladder.
00:07
It shows you the band and the size and where it runs on the gel.
00:11
Lane two is a dna sample cut by a single restriction enzyme from a plasmid.
00:19
So the question says, what will be the size of the original uncut dna fragment, assuming that all the original fragment has been completely digested? so according to our estimate, you have four fragments from lane two.
00:37
So one fragment is around 5 kb.
00:43
That's the longest fragment on the top of the gel.
00:47
The second fragment is between 2 and 3 kb, so it's most likely 2 .4 kb long.
00:58
This is the second from the top.
00:59
The third one is matching with the 2 kb band in the dna ladder.
01:08
So it is most likely a 2 kb band.
01:11
And the last fragment on the bottom, the smallest, is kind of compatible with 0 .5 kb.
01:19
So the question asks you about the size of the original uncut dna.
01:24
So the total size is going to be all the fragments add up together, 5 kb plus 2 .4 kb plus 2 kb plus 0 .5 kb.
01:45
So this is 9 .9 kb in total.
01:53
So this is the size of the uncut dna.
01:57
Now the second question, if the digested dna was a circular plasmid, right side of the figure, which would the restriction map of the corresponding plasmid look like? a, b, or c, or any or all would be possible.
02:14
So you can see that we have plasmid 1, or a we call it.
02:26
A has a pattern of, this is 2 kb and 2 .4.
02:36
Then you have 0 .5 here.
02:43
And then you have a 5 kb on the longer side.
02:49
And if you look at plasmid b, it has a different restriction site.
03:00
Again, you have a 2 kb fragment right here, but you have a different arrangement...