00:01
All right.
00:01
So in this problem, we're looking at dna replication.
00:05
And right now we have two identical chromosomes that show double -stranded dna.
00:15
So chromosome number one has a sequence of g -c -t -t.
00:24
I'm drawing it like this to show like a chromosome.
00:28
C -c -a -a -c -c -c -a -c -a.
00:34
A, and that is in the 5 prime to 3 prime direction.
00:45
And then the other side of this chromosome has to have the complementary nucleotides.
00:51
So we have c, g, a, a, g, g, g, t, that's 5 prime.
01:04
That's 3 prime up there.
01:06
Then we have two of them.
01:08
So they're going to look exactly the same.
01:10
G, c, t, t, c, c, c, a, and then just copy that.
01:23
A, a, g, g, g, t, 5 prime, 3 prime, 3 prime, 3 prime.
01:39
During replication, these chromosomes split down the middle and basically pair with free -floating nucleotides in the cell.
01:51
So if i have two chromosomes now, if i were to double this, that would then create four total chromosomes.
02:01
If you don't trust me, i can at least, i'll show this to you once, so we don't have to be super redundant.
02:06
But if i were to copy this chromosome here, you can imagine that the chromosome is going to split down the middle with an end time called dna helicase.
02:24
We've got more room now.
02:31
And you know what? we'll do it on the other side as well.
02:33
So here's the other chromosome, g -c -t, t, c, c, c, a.
02:44
And then across from that, there is a c -g.
02:52
G, g, t, t.
02:58
The directions of these chromosomes matter, these five primes and three primes, because that indicates which way the synthesis of a new molecule would occur.
03:15
You might not remember this, but the sugar in the backbone of dna, deoxyribose in dna and ribose and rna.
03:25
They label the different carbons on that sugar.
03:30
On one strand of dna, the 5 prime carbon is pointed closer to the edge and then down at the bottom end of the dna strand, the 3 prime carbon points closer to that end.
03:42
And new strands of dna are always synthesized in the 5 prime to 3 prime direction, meaning that in this strand right here, the 5 prime end would be opposite and the three prime end would be up here, and that can be a continuous synthesis...
