1. Chapter 5 Regular Biology
Cell Cycle and Mitosis
Chapter 5
Regular Biology

2. How Big are YOUR Cells?
Some cells like a RBC average in size of 8um in diameter
Nerve cells can reach lengths of 1 m but have small diameters
The cell with the largest diameter is the yoke of the ostrich egg measuring 8 cm

4. Why are cells limited to size?
The cells that make up a multi-cellular organism come in a wide variety of sizes and shapes
There are 3 REASONS Cell’s have limitations

5. 1. Diffusion Limits Cell Size
Although diffusion is a fast and efficient process over short distances, it becomes slow and inefficient as the distances become larger.
Because of the slow rate of diffusion, organisms can’t be just one giant-sized cell

6. 2. DNA Limits Cell Size
The cell cannot survive unless there is enough DNA to support the protein needs of the cell
In many large cells, more than one nucleus is present
Large amounts of DNA in many nuclei ensure that cell activities are carried out quickly and efficiently.

7. 3. Surface Area-to-Volume Ratio Limits Cell Size
As a cell’s size increases, its volume increases much faster than its surface area
If cell size doubled, the cell would require eight times more nutrients and would have eight times more waste to excrete
The surface area, however, would increase by a factor of only four

8. This problem would cause the cell to either starve to death or be poisoned from the buildup of waste products
2 mm
1 mm
4 mm
1 mm
2 mm
4 mm
1 mm
Surface area = 6 mm2 Volume = 1 mm3
2 mm
Surface area = 24 mm2 Volume = 8 mm3
4 mm

9. Cell Reproduction Remember in the Cell Theory states:
1. All cells come from preexisting cells
Cell division is the process by which new cells are produced from one cell
Cell division results in two cells that are identical to the original, parent cell.

10. As we go over this…
Right now…cells in your body are growing, dividing, and dying
Old are being shed & replaced, cuts & bruises are healing.

11. Discovery of Chromosomes
Chromosomes structures, which contain DNA and become darkly colored when stained, are and are carriers of the genetic material that is copied and passed from generation to generation of cells

12. Parts of the Chromosome
Centromere
Sister chromatids

13. DNA plus proteins is called chromatin.
One half of a duplicated chromosome is a chromatid.
Sister chromatids are held together at the centromere.
Telomeres protect DNA and do not include genes.
chromatid
telomere
centromere

14. Sister Chromatid
Sister Chromatids are pieces of identical DNA that are crucial in the process of cell replication and division.

15. Chromatin to Chromosomes
DNA wraps around proteins (histones) that condense it.
DNA double helix
DNA and histones
Chromatin
Supercoiled DNA

16. Centromere Sister chromatids Supercoil within chromosome Chromosome
Continued coiling within supercoil
Histone H1
Nucleosome
DNA

17. The Cell Cycle
The Cell Cycle is a regular pattern of growth, DNA replication, and cell divisions

18. The Cell Cycle
The events that occur during the cell cycle are a continuous process
2 major Groups Make the Cell Cycle
1. Interphase
2. Mitosis
Interphase

19. Centrioles replicate; cell prepares for division
Interphase
Not a true phase of mitosis, but prepares the cell for division
Interphase, the busiest phase of the cell cycle, is divided into three parts.
DNA synthesis and replication
Centrioles replicate; cell prepares for division
Interphase
Rapid growth and metabolic activity

20. Interphase Interphase prepares the cell to divide.
Parent cell
centrioles
spindle
fibers
Pair of
Centrioles -
centrosome
nucleus with
DNA-chromatin
Interphase prepares the cell to divide.
During interphase, the DNA is duplicated.

21. During Interphase Period of Growth for the cell by protein synthesis
G stands for GAP
1. Gap 1 or G1
2. S or Synthesis
3. Gap 2 or G2

22. The main stages Interphase
G1- cell growth and normal functions
S- DNA synthesis-copies DNA
G2- additional growth

23. Cells divide at different rates.
The rate of cell division varies with the need for those types of cells.
Some cells are unlikely to divide (G0)-nerve cells.

24. Interphase: the resting stage
Interphase Video Clip

25. Prophase, Metaphase, Anaphase & Telophase
Mitosis
Mitosis is the division of the nucleus or genetic material of a cell.
Mitosis is followed by the division of the cytoplasm: Cytokinesis
Steps of Mitosis
Prophase, Metaphase, Anaphase & Telophase
Plant More Apple Trees!

26. Mitosis Clip HMH VIDEO:

27. Prophase The longest phase of mitosis Double Chromosomes appear
Centrioles move to Opposite Poles
Spindle fibers appear
Chromosomes attach to spindle fibers by the Centromere
Nuclear membrane & nucleolus break down
Nucleus, Nuclear Envelope & Nucleolus disappear

28. Prophase

29. Prophase

30. Prophase: The First Stage of Mitosis
PROPHASE VIDEO CLIP

31. Metaphase
Double chromosomes (paired chromatids) attach to the spindle fibers by their Centromere and line up at the equator (middle of the cell)

32. Metaphase

33. Metaphase: The Second Stage of Mitosis
METAPHASE: VIDEO CLIP

34. Anaphase
Chromatids separate at the Centromere and begin to migrate to opposite poles
Centromeres lead the way
Chromatids cluster together when they reach the poles

35. Anaphase

36. Anaphase

37. Anaphase: The Third Stage of Mitosis
ANAPHASE: VIDEO CLIP

38. Telophase Chromosomes form Chromatin Nuclei forms around chromatin
Nucleus, Nucleolus, Nuclear Envelope & Nuclear Membrane re-appear
Cytoplasm divides

39. Telophase

40. Cytokinesis Division of the cytoplasm Begins in Telophase
A cleavage furrow forms in animal cells at the equator
A cell plate forms in plant cells and will become the cell wall

41. Cytokinesis differs in animal and plant cells.
In animal cells, the membrane pinches closed.
In plant cells, a cell plate forms.

42. Telophase: 2 New Daughter Cells

43. Telophase: The Last Phase of Mitosis
TELOPHASE VIDEO CLIP

44. Regulation of the cell cycle

45. Internal & External Factors
Both external & internal factors regulate the cell cycle
External Factors: come from outside the cell
Internal Factors: come from inside the cell

46. External Factors
External factors include physical and chemical signals.
Example: cell to cell contact
Most mammal cells form a single layer in a culture dish and stop dividing once they touch other cells.

47. Internal Factors External Factors can trigger internal factors
The most important factors are
1. Kinases: moves phosphate groups from one molecule to specific molecules
2. Cyclin: controls Kinase
Occasionally, cells lose control of the cell cycle

48. Apoptosis is programmed cell death.
a normal feature of healthy organisms
caused by a cell’s production of self-destructive enzymes
occurs in development of infants
webbed fingers

49. Loss of Control
Cancer is a malignant growth resulting from uncontrolled cell division
Cancer cells do not carry out necessary functions
Cancer cells come from normal cells with damage to genes involved in cell-cycle regulation.

50. Cancer cells form disorganized clumps called tumors.
Benign tumors remain clustered and can be removed.
Malignant tumors break away (metastasize), and can form more tumors.
cancer cell
bloodstream
normal cell

51. Cancer Therapy

52. Cancer
Cancer is the leading cause of death in the US exceeded by heart disease
Can affect any tissue in the body
Lung and Breast Cancer rate among the highest
Death Rate of Cancer

53. Most common: Breast, Lung, Prostate, Colon & Skin
Liver Cancer

54. The causes of Cancer 1. Inherited errors in specific genes
- Breast cancer
2. Exposure to radiation or chemicals
- Skin cancer
3. Some carried by viruses
- Cervical cancer
4. Environmental factors
- pollution, tobacco

55. Organisms reproduce by cell division
Asexual reproduction

56. Binary fission is similar in function to mitosis.
Asexual reproduction is the creation of offspring from a single parent.
Binary fission produces two daughter cells genetically identical to the parent cell.
Binary fission occurs in prokaryotes.
parent cell
DNA
duplicates
cell begins
to divide
daughter
cells

57. Some eukaryotes reproduce through mitosis.
Budding forms a new organism from a small projection growing on the surface of the parent.
bud
Hydra
Yeast

58. Fragmentation is the splitting of the parent into pieces that each grow into a new organism.
Vegetative reproduction forms a new plant from the modification of a stem or underground structure on the parent plant.