1. KEY CONCEPT Cell cycle regulation is necessary for healthy growth.

2. Internal and external factors regulate cell division.
External factors include physical and chemical signals.
Cell to cell contact is one type of physical signal.
Most mammal cells form a single layer in a culture dish and stop dividing once they touch other cells.
Growth factors are one type of chemical signal. They are proteins that stimulate cell division. They can affect a variety of cells or only specific cells.
Hormones are also chemical signals.

3. Two of the most important internal factors are kinases and cyclins.
Kinases- change the activity of other molecules by adding a phosphate group.
Cyclins- are rapidly made and destroyed at different points in the cell cycle.
External factors can trigger internal factors, which affect the cell cycle.

4. 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

5. Cancer is not one disease- there are many different types of cancer- all with different mechanisms.
Cancer is an accumulation of mutations in the genes that control cell division.
Can cancer be passed on to offspring?

6. Cell division is uncontrolled in cancer.
Cancer cells form disorganized clumps called tumors.
Benign tumors – not all tumors are cancerous. An abnormal mass of normal cells, they remain clustered and can be removed. They can cause health problems based on their location in the body.
Malignant tumors – masses of cancer cells, metastasize, or break away, and can form more tumors.
cancer cell
bloodstream
normal cell

7. Cancer cells do not carry out necessary functions.
Grow despite cell-cell contact or lack of growth factors.
Cancer cells come from normal cells with damage to genes involved in cell-cycle regulation.

8. Carcinogens are substances known to promote cancer.
Examples- tobacco smoke, air pollutants, radiation, mutated genes carried by viruses.
Standard cancer treatments typically kill both cancerous and healthy cells.
Examples- surgery, high energy radiation, chemotherapy.
Chemotherapy- antimitotic drugs- affect mitotic spindle, anti telomerases, aim- to be specific to cancer

9. Concept Check 9.4
1. List two differences between benign tumors and malignant tumors. 2. How might drugs that interfere with mitosis be effective in treating cancer? 3. How is cancer related to cell reproduction?