Cell division occurs through two main processes - mitosis and meiosis. Mitosis produces two identical daughter cells and is used for growth, development, and asexual reproduction in eukaryotic cells. It involves four stages: prophase, metaphase, anaphase and telophase. Meiosis produces gametes with half the number of chromosomes and occurs in sexual reproduction. There are checkpoints in the cell cycle to ensure cells do not divide if damaged or unhealthy. Loss of these controls can lead to uncontrolled cell growth and potentially cancer.

1. Cell Division

2. Cell Division
● Cell Theory…..All cells come from
preexisting cells: Parents and daughters
● Prokaryote vs. Eukaryote
● What are the major differences for these
cells?

3. Binary Fission
A type of cell reproduction for prokaryotic cells
DNA is copied and two identical cells are
formed.
Type of asexual reproduction

4. Meiosis
Mitosis

5. Meiosis
Cell division that occurs in egg and sperm.
Result in half the number of chromosomes:
Haploid
Produces Gametes

6. Mitosis
In eukaryotic cells
Occurs in
organisms
undergoing growth,
development,
repair or asexual
reproduction.

7. Cell Cycle
● A repeating set of
events in the life of a
cell
● Cell division is one
phase of this cycle
● Interphase is the time
between these divisions

8. Interphase
Three parts:
1. Cell growth (G1
)
2. DNA is copied (S)*** Important for division!
3. Growth and preparation for cell division (G2
)
* Special G0
phase: nervous system cells: when
one reaches maturity these cells seldom divide
again. Brain damage.

9. Stages of Mitosis
Prophase
Metaphase
Anaphase
Telophase

10. Prophase
● When DNA is formed into chromosomes -
two identical chromatids connected by the
centromere
● Nucleolus and nuclear membranes start to
disappear
● Centrosomes appear and special
microtubules called spindle fibers form.

11. Prophase
● In animal cells, centromeres
will also have centrioles,
which look like barrels
● The spindle fibers radiating
from the centrioles will
eventually attach to the
centromere on the
chromosome

12. Metaphase
The chromosomes line
up in the middle of the
cell with the spindle
fibers attaching to the
centromere of each
chromosome

13. Anaphase
When the fibers
retract splitting the
chromosomes in half
at the centromere
taking one copy of the
genetic material or
chromatid with it.

14. Telophase
Fibers start to
disappear, nuclear
membrane starts to
reform,
chromosomes loosen
up into their
chromatin state.

15. Control
● Through a series of checkpoints, specialized
proteins will decide whether a cell should
divide or not
● There are three check points, one at G1, G2,
and at Mitosis

16. Mitosis Checkpoint
If the cell passes through this checkpoint,
proteins will signal for the cell to enter back
into G1 phase

17. Loss of Control
What happens when the cell losses this control?
What happens when a cell that is not healthy
undergoes cell division?
How is this control lost?

18. Ibex
Penguin
Polar Bears