this presentation has detailed information on cell cycle. it includes steps as well as how the proteins take part in cell cycle.
i have also added information on some experiments that were carried out.
happy studying :)
HMCS Max Bernays Pre-Deployment Brief (May 2024).pptx
cell cycle in detail (interphase )
1.
2. Cell cycle
• The cell cycle or cell division is the series of
events that takes place in cell leading to its
division and duplication that produces 2
daughter cells
• Cell cycle is divided into 2 main phases
a) Interphase: which prepares cell for division
b) M phase: where division actually takes place
3.
4.
5.
6. Interphase
• It is most important part during the cell cycle
because once you prepare all things necessary
for cell cycle you cannot go back, so for
making the cell cycle happen it needs to have
many different proteins and chemicals inside
7. • Studies of frog oocytes
• Oocytes are arrested in the G2 phase of the cell cycle
until hormonal stimulation triggers their entry into
the M phase of meiosis
• In 1971, researchers Yoshio Masui and Clement
Markert, as well as Dennis Smith and Robert Ecker
found that oocytes arrested in G2 could be induced to
enter M phase by microinjection of cytoplasm from
oocytes that had been hormonally stimulated.
• This cytoplasmic factor was enough for the oocytes to
pass from G2 to M phase
• This was called as Maturation promoting factor
8. Further studies showed, however, that the
activity of MPF is not restricted to the entry of
oocytes into meiosis. To the contrary, MPF is also
present in somatic cells, where it induces entry
into M phase of the mitotic cycle. Rather than
being specific to oocytes, MPF thus appeared to
act as a general regulator of the transition from
G2 to M.
9. • The second approach to understanding cell cycle
regulation was the genetic analysis of yeasts, pioneered
by Lee Hartwell and his colleagues in the early 1970s
• Studying the budding yeast Saccharomyces cerevisiae,
these investigators identified temperature-sensitive
mutants that were defective in cell cycle progression.
• They underwent cell arrest
• For eg. Cdc28 protein is required for passage through
this critical regulatory point in G1
• A similar collection of cell cycle mutants was isolated in
the fission yeast Schizosaccharomyces pombe by Paul
Nurse and his collaborators.
10. cdc2 and cdc28 encodes a protein kinase—the first
indication of the prominent role of
protein phosphorylation in regulating the cell cycle.
Second, a human gene related to cdc2 was identified
and shown to function in yeasts, providing a dramatic
demonstration of the cell cycle regulators
11. • The third line of investigation was study of
protein synthesis in sea urchins
• Studies with protein synthesis inhibitors had
revealed that entry into M phase of these
embryonic cell cycles requires new protein
synthesis.
• In 1983, Tim Hunt and his colleagues identified
two proteins that display a periodic pattern of
accumulation and degradation in sea urchin and
clam embryos.
12. • These proteins accumulate
throughout interphase and are then rapidly
degraded toward the end of each mitosis
• Hunt called these proteins cyclins (the two
proteins were designated cyclin A and cyclin B)
and suggested that they might function to
induce mitosis, with their periodic
accumulation and destruction controlling
entry and exit from M phase.
13. Direct support for such a role of cyclins was provided in
1986, when Joan Ruderman and her colleagues showed
that microinjection of cyclin A into frog oocytes is
sufficient to trigger the G2 to M transition.
16. E2F protein
• It is an important protein because it
eventually leads the cell to go through G1 S
phase and finally enter there
• Not only cyclin but E2F is also important
• How is cyclin controlling things ?
• E2F is called transcription activation protein
