Full transcript
0:01[Music]
0:06cell cycle the cell cycle has three
0:10states which are quiescent interphase
0:13and mitosis and five phases G not g1 s
0:18g2 and M the quiescent state also known
0:24as a senescence state comprises of the G
0:27naught phase examples neurons cardiac
0:30muscle and RBC's interface state
0:34consists of g1 s and g2 phases and the
0:40mitosis state consists of the M phase
0:43prophase metaphase anaphase telophase
0:46occur during this phase the three major
0:50cell cycle checkpoints are the end of g1
0:54the end of g2 and during metaphase of
0:58the M phase progression through
1:02checkpoints is regulated by cycling's
1:05cyclin dependent kinases and tumor
1:08suppressors during the g1 phase cell
1:12cycle progression is controlled by a
1:14variety of different cellular mechanisms
1:17such as tumor suppressors genes that
1:21code for transcription factors proteins
1:24that detect DNA damage enzymes that
1:27allow the cell to progress to the S
1:29phase and signaling molecules that
1:31activate those enzymes the gene e to F
1:36regulates expression of transcription
1:38genes and cyclin dependent kinase to
1:41cyclin e and cyclin a if there is
1:46significant DNA damage p53 stimulates
1:50production of p21 p21 binds and inhibits
1:54all cyclin-cdk complexes which leads to
1:58arrest of cell cycle until the DNA
2:01damage is repaired and p21 levels drop
2:05the tumor suppressor retinoblastoma
2:07protein inhibits e to F expression
2:12cyclin D cdk4
2:14and cyclin d c d k6 complexes
2:17phosphorylate bread
2:19blastoma protein that leads to
2:21inactivation of retinoblastoma protein
2:23and expression of e to F the expression
2:28of e to F then leads to the expression
2:32of transcription genes and formation of
2:34cyclin e cdk2
2:36therefore the cell is pushed into the S
2:39phase cell cycle regulation in s and M
2:44phase cyclin a cdk2 is required for DNA
2:49synthesis cyclin a cdk1
2:52and cyclin b cdk1 promote the events of
2:55mitosis towards the end of mitosis the
2:59anaphase promoting complex causes
3:02ubiquitination and destruction of cyclin
3:05a cdk1 and cyclin b cdk1 that leads to
3:10termination of m phase with anaphase
3:14telophase and cytokinesis the most
3:18radiosensitive phases are the g2 phase
3:21and mitosis the least radiosensitive
3:24phase is the latter part of the S phase