The document discusses the cell cycle and cell division. It describes the stages of mitosis including interphase, prophase, metaphase, anaphase, telophase and cytokinesis. Chromosomes, kinetochores, spindle fibers and checkpoints are involved in regulating the accurate division of genetic material. Meiosis is also covered, which involves two cell divisions and a reduction in chromosome number important for sexual reproduction and genetic variation. Abnormal cell division can lead to cancer if cells escape normal cell cycle controls.

1. Cell Division
The Cell Cycle and Meiosis

2. Somatic Cellular Reproduction:
The Cell Cycle and Mitosis

3. Cells that make up the “body”.
Somatic Cells

4. Why do Somatic Cells Divide
Reproduction
Growth
Repair
Development
Surface : Volume
Maintain chromosome number

5. Structures that contain the genetic material
Chromosomes

6. Chromosomes
Composed of chromatin and proteins

7. Each Chromosome (after the S phase) contains
two identical parts called “sister chromatids”
attached at a centromere (referred to as
“double stranded”)

8. • Interphase and Mitosis
• The cycle of growth and division in all cells
The Cell Cycle

9. Interphase

10. Prophase

11. Metaphase

12. • Either of two
submicroscopic
attachment points for
chromosomal
microtubules, present on
each centromere during
the process of cell
division
Kinetochore

13. Mitotic Spindle
made of
microtubules

15. • Several microtubules
joined together create
structures known as
spindle fibers which
guide chromosomes
during mitosis.
Spindle
Fibers
Spindle Fibers
Spindle Fibers

16. Anaphase

17. Telophase

18. Cytokinesis

19. Identify the Stages of Mitosis
1 2 3
4 5

20. Cell Cycle
Regulation
Checkpoints during each
phase
Signals registered at the
checkpoints report the
status of various cellular
conditions (e.g., Is the
environment favorable? Is
the cell big enough? Is all
DNA replicated?

21. Molecular protein clocks that regulate the
activities of the cell cycle in a particular
order
Levels controlled by genes:
Proto-Onco Genes Stimulate
Tumor Supressor Genes Inhibit (p53 is a
common example)
p53 is a protein that functions to block the
cell cycle if the DNA is damaged. If the
damage is severe this protein can cause
apoptosis (cell death).
Cyclin Dependent Kinases

22. Cell Growth and Division
Also Regulated By
External Factors:
Density
Growth Factors

23. Cancer
Cancer cells do
not respond
normally to the
body's control
mechanisms.
They divide
excessively,
invade other
tissues and, if
unchecked, can
kill the whole
organism.
Abnormal cells
which have
escaped normal
cell-cycle
controls are the
products of
mutated or
transformed
normal cells.
A p53 mutation
is the most
frequent
mutation
leading to
cancer because
it prevents
apoptosis.

24. Malignant Tumors and Metastasis

25. Meiosis

26. Why Meiosis?
Sexual
reproduction
Reduction of
chromosome
number
Genetic
recombination

27. Prophase I

28. Metaphase I

29. Anaphase I

30. Telophase I

31. Meiosis I

32. Prophase II

33. Metaphase II

34. Anaphase II

35. Telophase II

36. Meiosis II

37. Crossing-Over

38. Nondisjunction