1. CHROMOSOMES

2. Chromosomes are composed of DNA, and are found in the nucleus of cells.

3. DNA contains the genetic material, or genes.

4. Genes are lined up on chromosomes like the cars on a freight train.

5. Organisms have tens of thousands of genes that control different traits.
Genes play
an important
role in
determining
how a person’s
body develops
and functions.

6. Human body cells have 46 chromosomes.

7. How does DNA fit inside the nucleus of a cell?
If you took one of your cells and stretched out
the chromosomes and laid them end to end,
the DNA would be about 3 meters long.
How does DNA fit inside the nucleus of a cell?

8. DNA wraps around proteins that help organize and condense it.
The DNA strands are highly coiled.

9. REVIEW!!

10. THE CELL CYCLE

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

12. 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!

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

14. The cell cycle A repeating sequence of cellular growth, DNA replication, and cell division .

15. The cell cycle can be divided into three stages:
Interphase
Mitosis
Cytokinesis

16. During interphase…..
The cell grows.
Cells also increase in size,
and organelles increase in number.

17. During interphase…..
The cell works…and works
The cell carries out its normal functions.
Red blood cells--
Carry oxygen
Muscle cells---
contract to move joints

18. During interphase…..
The cell copies its DNA .
At the end of this stage,
the nucleus contains
two complete sets of DNA.

19. CELL CYCLE
The cell spends
most of its life
in interphase.

20. Interphase is followed by cell division.

21. Cell division involves: Mitosis Cytokinesis.

22. Mitosis occurs first.
CELL
DIVISION

23. 2. Mitosis: The division of the cell nucleus
into two identical nuclei.
one nucleus
two nuclei

24. Mitosis is followed by cytokinesis.
CELL
DIVISION

25. 3. Cytokinesis:
The division of the cytoplasm.

26. REVIEW CELL CYCLE
Cell
Division

27. CELL DIVISION MITOSIS & CYTOKINESIS
Making new cells

28. Why does cell division occur?
To make new cells…
To replace old
or dead cells
To replace cells
destroyed by injury
Skin cells

29. for growth and development.

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

31. This protist is reproducing asexually.

32. YOU are here because of cell division.
The one cell
divided to produce
2, then 4,
then 8, 16, 32, …..
cells
You began life
as one cell
And continued to
divide…
zygote

33. As old cells die, new cells are produced.
New cells are produced by cell division.
One cell divides to form two new cells.
cell
division
one
cell
two
identical
cells

34. How do cells divide? Is this a problem???? What can a cell do???? 2346 23
Is this a problem????
What can a cell do????

35. Before a cell can divide, it must duplicate/copy its DNA.
4 chromosomes 4 4
DNA is
duplicated 8
cell
divides 4
Identical!
New cells identical to original cell.

36. 4 4 8 4 Identical! New cells have same number of
4 chromosomes
4 chromosomes 4 4
DNA is
duplicated 8
cell
divides 4
Identical!
New cells have same number of
chromosomes as the original cell.

37. A cell duplicates its DNA during interphase.4
chromosomes 8
chromosomes
DNA is duplicated

38. During interphase, a cell duplicates its DNA….
4 chromosomes
8 chromosomes
DNA
duplicates
nucleus

39. Interphase….DNA is duplicated
chromosomes
4 chromosomes …..double
nucleus
cell
DNA in chromosomes
DNA is
duplicated
nucleus
cell
chromosomes in cell
4 chromosomes ….single

40. the cell proceeds to divide.
After Interphase,
the cell proceeds to divide.
Cell
division

41. Cell division involves: Mitosis Cytokinesis.

42. MITOSIS pmat There are four phases in mitosis: 1. prophase
Remember me!
There are four phases in mitosis:
1. prophase
2. metaphase
3. anaphase
4. telophase
pmat

43. 1. Prophase DNA condenses into tightly coiled chromosomes.
Duplicated chromosomes
consist of two identical copies.
pro = chromosomes
condensed
cell

44. Condensed duplicated chromosomes
are x - shaped

45. 2. Metaphase Chromosomes line up along the middle/center of the cell.
meta = middle

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

47. 3. Anaphase Chromosomes are pulled apart and
move to opposite ends of the cell.
Ana = Apart
Chromosomes
pull apart

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

49. 4. Telophase The chromosomes have reached opposite ends of the cell
telo = two nuclei
The nuclear
membrane
starts to form.
Two nuclei form.

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

51. Cytokinesis The cytoplasm divides, forming two identical cells.
DNA
The cells can now go about their business.

52. After the cell undergoes mitosis and cytokinesis, the two new cells produced are identical to the original cell.

53. Recap….Making more cells
Organisms are always in need of more cells.
Organisms make more cells by cell division.
Cell division = mitosis cytokinesis

54. Recap…..Mitosis
Mitosis is
Division of the nucleus

55. P M A T Recap…..Mitosis Which are the phases? --- prophase
Remember me!
Which are the phases? P M A T
--- prophase
pro =
chro
- chromosomes condensed
--- metaphase
meta =
middle
- chromosomes in middle
--- anaphase
ana =
apart
- chromosomes move apart
--- telophase
telo =
two
- two nuclei

57. MITOSIS 4
chromosomes
One cell 4
chromosomes
Two cells

58. MITOSIS
produces two cells with the same number
of chromosomes as the original cell
… produces two identical cells

59. Regulating the Cell Cycle
Some cells divide every few hours…cells lining stomach.
Some cells never divide….brain cells
How do cells know when to divide?

60. There are many different proteins that
regulate the cell cycle and cell division.
Proteins…workhorses of the cell!!!

61. Regulating the Cell Cycle
Most cells will divide until they come in contact
with other cells.
Once the cells come in contact with other cells,
the cells stop dividing.
Example: Injury

62. 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.

63. Cancer cells divide forming a mass of cells called a tumor.
Benign tumors do not spread.
Malignant tumors spread and destroy healthy tissue.

64. Cancers are caused by defects in the genes
that regulate the cell cycle and cell division.
The defect or mistake in the gene (DNA) results in the production of a defective protein
that is unable to regulate the cell cycle.
As a result, the cell divides uncontrollably.