00:02
So in the lab, you're given a sample of a non -dna you want to characterize it.
00:06
First of all, you ran a specter potometry to make sure that it's pure and it has enough concentration to be seen, and then you run an aggroce gel to estimate its size.
00:17
Since you forgot to add ethylchid bromide into the gel, before casting, loading, so you had to post -standing when the gel atrophyset is over.
00:25
But at the end of the lab, when you compare your results with your fellow student results, you realize that you have different results.
00:31
Their results suggested that the dna molecule is a lot smaller than yours.
00:36
So means the dna runs at a lower position on the gel than yours.
00:40
So how can you explain this difference? assuming that there's no dna degradation happens.
00:45
So first of all, what is theethium bromide? ethidium bromide is a dna intercalidors.
00:49
We use that to stain our dna, so the dna can be visualized under uv light.
00:55
So as you can see, i draw a double helix structure of dna.
00:58
The rat molecules are thetium bromide.
01:00
So during gel running, these ethydean bromide insert itself into the dna between the base pair.
01:07
So then when the electrophoresis is over, you put the gel underneath the uv light, you will able to see where the dna is.
01:15
But this is the benefit of ethydine bromide, but it has its downside.
01:19
So when ethyden bromide is added into the gel, a lot of ethythine bromide molecules were inserted into the dna.
01:27
This actually changed the dna mobility in the agarose gel by modifying its shape...