00:01
Hello everyone, in this question we have been, we have to talk about the cell cycle, that is the interphase mitosis and cytokinesis.
00:12
So here we have been said, explain why it is essential that genome of cell be copied before a cell divides into two.
00:22
So here basically the dna replication takes place in the s phase and it must accurately duplicate its genetic information encoded in the dna in order for its progeny to function and survive.
00:46
So this is a complex problem because of the great length of dna molecules.
00:51
So each human chromosome consists of long double spiral or helix, each strand of which consists of more than 100 million nucleotides.
01:00
So accurate dna replication is crucial to ensure that the daughter cells here get the exact copy of this genetic information for synthesizing the protein because one cell will be divided into two daughter cells.
01:16
So if it is deployed in numbers, these daughter cells also needs to be deployed in number in mitosis.
01:23
So therefore, if the genetic information will not be double, then the cells here will not receive the equal number of the information.
01:32
So accuracy is achieved by a proofreading ability of the dna polymerase itself.
01:37
So dna replicates in a semi -conservative manner.
01:40
So each chromosome is formed of two sister chromatids joined at centromere or primary constriction.
01:47
Then we have been asked that what happens to the cell in cytokinesis and then in the question 2 we have been asked about the certain mechanism that takes place in the cell division.
02:02
So first is the spindle apparatus assemble.
02:06
So spindle apparatus assembles during the pro -phase in which the chromatin also starts to condense and the spindle fiber starts to assemble so that in metaphase it can align the chromosome during the at the equatorial plate.
02:22
Then it says spindle apparatus disassembles.
02:25
So it happens in telophase because now almost the cell cycle is completed.
02:29
So that is why the nuclear membrane starts to form and the spindle fiber starts to disassemble.
02:35
Then it says chromosome condensation.
02:38
So as we have already discussed, it happens in pro -phase.
02:41
Then in the next question, it says that the chromosome decondense.
02:46
So this here takes place in telophase.
02:49
So this is complete opposite of the pro -phase and then it says nuclear envelope fragments.
02:57
So that also takes place in pro -phase.
02:59
So before beginning the cell division, the nuclear membrane and organelles starts to disappear.
03:05
Then it says that nuclear envelope reforms.
03:09
So that takes place in the telophase.
03:12
Then it says that chromosome line up at the midpoint of the cell cycle...