1. THE CELL CYCLE

2. All organisms have a life cycle:
birth growth reproduction death

3. Within all organisms, cells are also “born”, grow, reproduce/divide, and die.
CELL TYPE
LIFE SPAN
Lining of the intestine
4-5 days
Skin cell
2 weeks
Red blood cell
4 months
Liver cell
days
Brain cells
100 years
Brain cells do not divide…
you are born with all your brain cells you will ever have!

4. Cell Cycle
- cells are born
- cells grow and work
- cells divide to make new cells
- cells die

5. CANCER: Uncontrolled Cell Growth
a disorder in which body cells lose the ability
to control cell growth and cell division.
Cancer cells do not respond to signals
that regulate their cell cycle;
As a result cells divide uncontrollably.

6. Before a cell divides, it must….
The cell copies its DNA .
At the end of this stage,
the nucleus contains
two complete sets of DNA.

7. During DNA replication…..
C G
&
T A
G C

8. Perform DNA replication
on the following DNA strand:
T G A T T C G T A G C C A A C T A A G C A T C G G T

9. Perform DNA replicationG A C
--- A C T G

10. Perform DNA replicationG A C
--- A T
--- A C T G
--- C G
---
--- T A
---
--- A T
---
--- C
--- G
--- T A
--- G
---
--- C
--- T
--- A

11. Perform DNA replicationG A C
--- A C T G

12. Perform DNA replicationG A C
--- A T
--- A C T G
--- C G
---
--- T A
---
--- A T
---
--- C
--- G
--- T A
--- G
---
--- C
--- T
--- A

13. DNA Replication

14. DNA Replication

15. CELL DIVISION MITOSIS

16. Why do cells undergo mitosis?
To make new cells…
To replace old
or dead cells
To replace cells
destroyed by injury
Skin cells

17. for growth and development.

18. to produce a new individual --- asexual reproduction
the production of genetically
identically offspring from
a single parent…a clone.

19. MITOSIS pmat There are four phases in mitosis: 1. prophase
2. metaphase
3. anaphase
4. telophase
pmat

20. Before mitosis, DNA must be… duplicated
cell
DNA
Replication
cell

21. Prophase
The duplicated chromosomes condense.
cell

22. Metaphase
Chromosomes line up along
the middle of the cell.

23. Anaphase Chromosomes are pulled apart and
move to opposite ends of the cell.

24. Telophase The chromosomes gather at opposite poles
of the cell forming two nuclei.

25. Cytokinesis
The cytoplasm divides,
forming two identical cells.

26. telophase

27. cytokinesis

28. metaphase

29. anaphase

30. interphase

31. prophase

32. MEIOSIS

33. Why do cells undergo meiosis?
To make egg and sperm for sexual reproduction
gametes
Eggs are made in the ________
ovaries
Sperm are made in the _______
testes

34. Body Cells vs Gametes 46 chromosomes 23 chromosomes Homologous pairs
Mom & Dad pairs
Homologous pairs
Unpaired chromosomes
Diploid cell
Haploid cell

35. A Body cell
A diploid cell
Homologous pairs

36. A sex cell
A Gamete --- _________
A haploid cell
Half the chromosomes

37. MEIOSIS 1 4 2n diploid cell haploid cell (gametes) n n n n 24
chromosomes 12
chromosomes

38. Interphase Meiosis I Meiosis II DNA Replication
Homologous
chromosomes
separate
DNA/Chromosomes duplicate
Sister chromatids separate

39. MEIOSIS There are eight phases in meiosis: 1. prophase I
2. metaphase I
3. anaphase I
4. telophase I
Meiosis I
5. prophase II
6. metaphase II
7. anaphase II
8. telophase II
Meiosis II

40. 1. Prophase I
Crossing-over
Homologous chromosomes
pair up

41. 2. Metaphase I
middle

42. 3. Anaphase I
Homologous
chromosomes
separate
middle

43. 4. Telophase I
cytokinesis

44. 5. Prophase II

45. 6. Metaphase II
middle

46. 7. Anaphase II
middle

47. 8. Telophase II End result: Four haploid cell (n)
Each of the four cells is
genetically different
from each other and
from the parent cell.

49. & Asexual reproduction
MITOSIS vs MEIOSIS
Makes body cells
& Asexual reproduction
Makes gametes
(egg & sperm) 24 12 12 24 24 24 12 12
1 cell
2 cell
1 cell
4 cell 24
chromosomes 24
chromosomes 24
chromosomes 12
chromosomes
Asexual reproduction
produces identical offspring
…no genetic diversity
Sexual reproduction produces
genetical different offspring
…large genetic diversity