00:01
This question is asking about the mechanism of intrinsic as well as the extrinsic pathway of apoptosis.
00:08
The first one is intrinsic pathway.
00:13
It is also called as mitochondrial dependent pathway or it is also called as receptor non -mediated pathway.
00:23
And the steps that are involved in this pathway are represented as follows.
00:27
When there occurs the severe double standard dna breaks inside the cell, say this is the double standard dna break, then these damages are sensed by atm -atr pathway, which is actually a kinase -dependent pathway, and these pathways leads to the activation of chk 1 or 2, that is the checkpoint kinase 1 or 2.
00:52
These kinages then phosphorylate the p -53 protein, and upon phosphorylation, the p -53 protein gets activated.
01:02
The p -53 protein will act as the transcription factors, and so they causes the transcription of p -21 proteins, as well as some of the pro -aboptotic factors.
01:16
The p -21 proteins are actually the inhibitors of g1 cycling e -cdk2 complex.
01:27
And so this will lead to g1 arrest.
01:31
On the other hand, some of the examples of pro -apoptotic factors include spuma, noxa, back and backs.
01:42
Now these back and backs pro -apoptotic factors heterodimerize on the outer mitochondrial membrane.
01:50
And this will lead to the creation of a pore which is called as vdac, that is the voltage dependent.
01:56
An ionic channel on the mitochondrial membrane.
02:01
Through this vdac channel there occurs the influx of ions inside the mitochondria and this influx of ions further causes the efflux of cytocrine c from mac of the mitochondria, which is actually mitochondrial, apoptosis induced channel.
02:23
Now the cytochrome c enters into the cytosol where it binds to another factor named as apaf1, which is the aboptotic protease, activator factor 1 and their binding is catalyzed by atp hydrolysis.
02:39
This atp hydrolysis causes the oligomerization of apap1 in the cytosol and this oligomerization leads to the formation of apoptosome complex.
02:51
This apoptosome complex causes the proteolytic cleavage and thereby the activation of pro -caspase 9 into caspase 9 and this caspase 9 further causes the activation of pro -caspase 3 or 7 into caspace 3 or 7.
03:18
Now the caspace 3 or 7 will act as dnas, that is it causes the fragmentation of dna, it also causes nuclear fragmentation...