When Good Cells Go Bad Cell Cycle Control & Cancer

The Cell Cycle

Not all cells in the body go through the cell cycle at the same rate –Muscle and nerve cells never go through mitosis after they mature. –Liver cells go through mitosis about once a year. –Skin cells go through mitosis every few hours.

Rate of Cell Division Contact inhibition is turned off or on as needed. Example, if a bone breaks the cells near the break will begin to divide until the break is filled.

Cyclins and Growth Factors Proteins that regulate timing of cell cycle –Make sure cell cycle does not proceed until all previous steps have been completed. Cyclins – cell cycle does not continue until previous steps are complete

Cell Cycle Control G 1 checkpoint – Has the correct signal to divide been given?

Cell Cycle Control G 2 checkpoint – Is the cell ready to divide?

Cell Cycle Control M checkpoint – Are chromatids aligned at equator?

Cyclins and Growth Factors Proteins that regulate timing of cell cycle –Make sure cell cycle does not proceed until all previous steps have been completed. Cyclins – cell cycle does not continue until previous steps are complete –Respond to events in the body to speed or slow cell division. Growth factors – stimulate mitosis for wound healing

Apoptosis Programmed cell death (cell suicide” –When a cell is old, damaged, or no longer needed, it systematically dismantles itself.

Cancer Cancer – a cell that divides inappropriately Mutations in DNA that control cell cycle Accumulations of multiple mutations transform normal cell to cancer cell –Each cancer cell has 6 – 8 mutations in genes that: Control the cell cycle Control cell death Allow cell to obtain nutrients and move throughout the boyd

Cancer Oncogenes – genes that encourage cell division (gas pedal) Tumor-suppressor genes – genes that inhibit cell division (brakes) In cancer cells, these genes are mutated. (Gas pedal gets stuck and brakes don’t work.)

How Cancer Grows Interactive Activity 02_int_howcancergrw/ 02_int_howcancergrw/ Answer the following questions: 1.What are some ways cancer cells develop abnormally? 2.What are some ways that cancer cells differ from normal cells? 3.How does the body respond to cancer cells?