Yash Gupta B.Tech Biotechnology Bundelkhand University Jhansi

1. Cell cycle and
its regulation
PRESENTED BY
YASH GUPTA
B.TECH BIOTECHNOLOGY

2. CELL CYCLE Term cell cycle was
proposed by Howard
and Pelc.
 Cell cycle is the cyclic
representation of events
of cell division.
 Cell cycle is the name
we give the procedure
through which cells
recreate and make two
new cells. Cell cycle has
various stages called
G1, S, G2, and M .

3. STAGES OF CELL CYCLE
I. Interphase
1. G1 Phase
2. S Phase
3. G2 Phase
II. M- Phase
Karyokinesis
A. Prophase
B. Metaphase
C. Anaphase
D. Telophase
Cytokinesis
A. Cell Plate Formation (in plants)
B. Cell Furrow Formation (in animals)

4. G1 > S > G2 > M
DURATION OF VARIOUS STAGES OF CELL
 One turn of cell cycle is
usually completed in 24
hours, in embryogenic
cells.
 But time period is never
constant because
different cell of
different species takes
different time period for
cell cycle.

5. INTERPHASEInterphase is the
longest stage in the
eukaryote cell cycle.
Metabolically most
active phase but
Cytologically resting
phase.
G1 is metabolically and
biochemically most
active phase.
G1 > S > G2

6. ● Also called phase of cell
differentiation.
● It is the resting phase.
● In these cells Cyclin D is in
decreased concentration.
● Quiscence of cell can be
reversible or irreversible.
G0 PHASE

7. G1 Phase
-It is the Ist growth
after cell division.
Events are:
●Biosynthesis of
dNTPs(dATP, dGTP ,
dTTP)
●Biosynthesis of
amino acids.
●Synthesis of cyclin
proteins.
●Active Gene
Expression.
●Synthesis of ATP and
GTP.
●Transcription

8. S Phase
- S Phase is called
Synthesis Phase.
Events are :
● DNA doubling.
●Histones Synthesis.
●Centriole Synthesis.

9. G2 Phase
- It is the Second
growth phase.
Events are :
●Repair of DNA
damage which have
occurred during
●DNA replication.
●Histone DNA
packaging to form
chromatin.
●Repression of gene
activity begins.

10. MITOSIS
◙ It was first discovered by Strassburger in onion root tips.
◙ only occurs in Eukaryotes.
◙ Division of nucleus occurs, one parent cell divides into two daughter cells
and both are identical to each other (genetically homogenous).
◙ The chromosome number and karyotype of the cell remains constant.
◙ Does not occurs in some cells such as Brain Cells.

11. MEIOSIS
▲It was first reported by Farmer and Moore in anther of anion flower
bud.
▲It is the process in which two meiotic divisions occurs and parent cell
divides two times thus giving rise to four daughter cells—
Meiosis I and Meiosis II
▲Original cell is diploid (2n).
▲Meiosis I is called Reductional Division or Heterotypic Division.
▲Meiosis I is called Equational Division or Homotypic Division.

12. REPLICATION OF CELL

13. REGULATION OF CELL CYCLE
The whole course of cell cycle is tightly
regulated by the protein layers:
◊ Cyclin proteins (Regulatory proteins for
cell cycles)
◊ Cyclin dependent kinases
(CDK)(catalytic proteins of cell cycle)
◊ Structural Maintenance Chromosomal
Proteins (SMC) (non-histone proteins)
◊ Anaphase Promoting Complex (APC)

14. THANK YOU