00:01
Hello students, here the question is about the semi -conservative model of dna replication or the experiment of messensen's style.
00:10
So the question is that a line of mouse cells has grown for many generations in a medium with 15n and cells in g1 are then switched to a new medium that contains 14n.
00:17
We have to identify or the draw a pair of homologous chromosomes from these cells at the following stages showing the two strands of dna molecule found in the chromosome.
00:26
So here when mouse cells are grown in a medium containing 15n, the nitrogen isotope 15 is incorporated in the nucleotide as seen in the diagram.
00:38
So these results in both the standards of dna being labeled in dna.
00:42
So this is both 15n and 15n.
00:48
There are two strands is 15n and 15n.
00:51
Next in the g1 phase the cells are switched to a medium containing 14n which is a lighter nitrogen isotope as the cells divide and replicate their dna.
01:00
So the dna strands will gradually be replaced with the 14n instead of 15n.
01:10
So this is a red, the red is 14n and this is the conservative, the semi -conservative...