00:01
There, this question is dealing with shargaft's rule.
00:07
And shargaft's rule shows that in a double -stranded dna, the amount of guanine equals the amount of cytosine, and the amount of adenine equals the amount of thymine.
00:31
Well, this makes sense because those are the ones that bond together.
00:38
Those are the nitrogen bases that pair together.
00:41
So if we have our double -stranded dna here, when we look at the nitrogen bases, anytime there's an adenine, it's going to pair with a fymine.
00:56
Or it could be a fymine on this side and adamine on that side.
01:00
But that means that we're going to have an equal amount of c and g, or of c equaling g, and an equal amount of a -equaling t.
01:12
That does not mean that the two of these are equal.
01:15
In other words, we could have a strand where 20 % of our bases are guanine.
01:20
Well, that means 20 % of our bases would also be cytosine.
01:23
So this is just an example.
01:25
This is not always going to happen.
01:28
But this is an example.
01:29
Well, that's 40 % of our total bases.
01:32
That means 60 % of the bases are adenine or thymine, but those have to be equal to each other.
01:38
So that would mean we would have 30 % of each of these.
01:41
So this is going to help us answer our first question.
01:45
Because our first question says, does shargaf's rule imply that equal amounts of guanin and adding are present in dna? so does g equal a? and the answer to that is absolutely not, as we showed here in my example.
02:07
So that is a no.
02:09
Those amounts are not necessarily going to be equal.
02:13
Right.
02:14
Let's look at letter b.
02:15
Does shargaft's rule imply that the sum, of the purine residues equals the sum of the perimity...