1. The Cell Cycle and Cell Death
SNC2D

2. Cell Reproduction
Mitosis in animal cells looks very like mitosis in plant cells:

3. Interphase
The cell prepares for cell division by growing (producing new proteins and organelles) and by synthesizing copies of its DNA (the chromatin).

4. Prophase
During the first phase of mitosis, the chromatin condenses into chromosomes and the nuclear structure disintegrates. A framework called the mitotic spindle forms.

5. Metaphase
Next the chromosomes line up in the middle of the cell.

6. Metaphase Next the chromosomes line up in the middle of the cell.
In an animal cell, at the end of the spindle fibres at the poles are the centrioles.

7. Anaphase
The chromosomes separate and are pulled to opposite ends of the cell.

8. Telophase and Cytokinesis
In the last stage of mitosis, the cell divides the cytoplasm into two portions. The final separation of the cytoplasm into two distinct cells is called cytokinesis.

9. Rate of Mitosis
Different parts of an organism experience different rates of mitosis (e.g. an onion root tip is where growth occurs and therefore the cells divide frequently, every 12 – 36 hours).

10. Rate of Mitosis
In humans, skin cells (that brush off) or intestinal cells (that are broken down by the digestive process) have high rates of mitosis, whereas red blood cells may last for months.
human skin cells

11. Apoptosis
The regulated death of a cell that is no longer useful (e.g. white blood cells post-infection) or has lost its ability to function efficiently is called apoptosis.

12. Apoptosis
The regulated death of a cell that is no longer useful (e.g. white blood cells post-infection) or has lost its ability to function efficiently is called apoptosis.

13. Apoptosis
The material of the cell is recycled by the body.

14. Cancer
What happens when damage to a cell impairs its ability to commit apoptosis and it divides and divides and divides?
cancer

15. Exponential Growth
Consider what happens if 1 cell out of starts dividing uncontrollably.
The remaining 999 will die as often as they are replaced.
That 1 cell . . .

16. Exponential Growth # of divisions normal cells cancer cells 0 999 1 1 1 2 3 4 5 6 7 8 9 10

17. Exponential Growth # of divisions normal cells cancer cells 0 999 1 2 3 4 5 6 7 8 9 10

18. Exponential Growth # of divisions normal cells cancer cells 0 999 1
3 Keep going 4 5 6 7 8 9 10

19. Exponential Growth # of divisions normal cells cancer cells 0 999 1

20. The Beginning of Cancerous Growth
National Cancer Institute
Understanding Cancer and Related Topics
Understanding Cancer
Cancers grow more quickly
where cells divide frequently.
Cancerous growths are called tumours.
Underlying tissue
NCI Web site:

21. Invasion and Metastasis Understanding Cancer and Related Topics
National Cancer Institute
Understanding Cancer and Related Topics
Understanding Cancer
Cancer cells can invade surrounding tissues and blood vessels.
NCI Web site:

22. Invasion and Metastasis Understanding Cancer and Related Topics
National Cancer Institute
Understanding Cancer and Related Topics
Understanding Cancer
Cancer cells can invade surrounding tissues and blood vessels.
They can also be transported by the circulatory system to other parts of the body (metastasis).
Cancer cells then grow at the new locations.
NCI Web site:

23. Malignant versus Benign Tumors Understanding Cancer and Related Topics
National Cancer Institute
Understanding Cancer and Related Topics
Understanding Cancer
Malignant cells invade neighboring tissues, enter blood vessels, and metastasize to different sites.
Benign tumor cells grow only locally and cannot spread by invasion or metastasis.
Time
NCI Web site:

24. Why Cancer Is Dangerous Understanding Cancer and Related Topics
National Cancer Institute
Understanding Cancer and Related Topics
Understanding Cancer
Melanoma (skin cancer) cells can travel through the circulatory system.
The cancer that spreads to the liver would be called metastatic melanoma, not liver cancer.
Liver
Melanoma (initial tumor)
NCI Web site:

25. Cancer Detection and Diagnosis Understanding Cancer and Related Topics
National Cancer Institute
Understanding Cancer and Related Topics
Understanding Cancer
Cancerous tumours can be detected by medical imaging
(x-ray, ultrasound, and MRI scans).
NCI Web site:

26. Cervical Cancer Screening Understanding Cancer and Related Topics
National Cancer Institute
Understanding Cancer and Related Topics
Understanding Cancer
Normal
Pap smear
But even earlier stages of cancer can be detected by screening cells.
Normal Pap smear
Abnormal Pap smear
Abnormal
Pap smear
NCI Web site:

27. Cervical Cancer Screening Understanding Cancer and Related Topics
National Cancer Institute
Understanding Cancer and Related Topics
Understanding Cancer
Normal
Pap smear
But even earlier stages of cancer can be detected by screening cells.
Biopsies similarly look at cells inside suspected tumours.
Normal Pap smear
Abnormal Pap smear
Abnormal
Pap smear
NCI Web site:

28. Cancer Cells Look Different Understanding Cancer and Related Topics
National Cancer Institute
Understanding Cancer and Related Topics
Understanding Cancer
NCI Web site:

29. Understanding Cancer and Related Topics
Hyperplasia
National Cancer Institute
Understanding Cancer and Related Topics
Understanding Cancer
Sometimes screening detects an excessive rate of cell division called hyperplasia – the cells are still normal and the process is reversible.
An example of hyperplasia would be a callus on your hand.
Normal
Hyperplasia
NCI Web site:

30. Understanding Cancer and Related Topics
Dysplasia
National Cancer Institute
Understanding Cancer and Related Topics
Understanding Cancer
Also detectable is dysplasia: excessive growth and abnormal tissue arrangement.
Normal
Hyperplasia
Mild dysplasia
NCI Web site:

31. Carcinoma in situ (severe dysplasia)
National Cancer Institute
Understanding Cancer and Related Topics
Understanding Cancer
Normal
Hyperplasia
Mild dysplasia
Carcinoma in situ (severe dysplasia)
Dysplasia is often monitored to make sure it doesn’t develop into a metastatic cancer.
Cancer (invasive)
NCI Web site:

32. Understanding Cancer and Related Topics
National Cancer Institute
Understanding Cancer and Related Topics
Understanding Cancer
Some viruses or bacteria
Some chemicals
Radiation
Heredity
Diet
Hormones
What Causes the Cell Damage that Leads to Cancer?
NCI Web site:

33. Population-Based Studies
We can determine possible causes of cancer by looking at the incidence in different populations:

34. Incidence in Populations
The higher incidence of colon cancer in Japanese families that have moved to the U.S. suggests that it’s behavioural and/or environmental factors are what is changing the risk.

35. Understanding Cancer and Related Topics
National Cancer Institute
Understanding Cancer and Related Topics
Understanding Cancer
Look For Correlations
Correlation Between Meat Consumption and Colon Cancer Rates in Different Countries 40 30
Number of Cases (per 100,000 people) 20 10 80
100
200
300
Grams (per person per day)
NCI Web site:

36. Some chemicals can damage cells
National Cancer Institute
Understanding Cancer and Related Topics
Understanding Cancer
Some Cancer-Causing Chemicals in Tobacco Smoke
Some chemicals can damage cells
NCI Web site:

37. How Can We Show the Risk?

38. And Skin Cancer is Correlated with UV Exposure

39. Viruses Some viruses are also linked to certain cancers
(e.g. human papillomavirus to cervical cancer).
Virus inserts and changes genes for cell growth

40. Textbook Questions
p. 36 #1 – 5
p. 37 #1 – 5, 7, 8, 10