1 Review Name the two types of proteins that regulate the cell cycle and how do they work Form a Hypothesis Write a hypothesis about what you think would happen if cyclins were injected into a cell during mitosis. How would you test your hypothesis 2 Compare and Contrast How are the growth of a tumor and the repair of a scrape on your knee similar and how are they different 3 Infer Why do you think it is important that cells have a “control system” to regulate the timing of cell division

Ch 10 Cell Growth and Development 10.3 Regulating the Cell Cycle

Controls on Cell Division Controlled by regulatory proteins both inside and outside the cell Can be turned on and off Cells are stimulated to divide rapidly with a broken bone and slow when healing nears completion.

Cyclins Proteins that regulate the timing of the cell cycle.

Regulatory Proteins Internal regulators External regulators Respond to events inside a cell Allow the cell cycle to proceed only once certain processes have occurred External regulators Respond to events outside the cell Direct cells to speed up or slow down the cell cycle.

Regulatory Proteins Growth factors External regulators that stimulate the growth and division of cells Embryonic development and wound healing.

Apoptosis Programmed cell death Plays a role in development in shaping structures- fingers.

Cancer Uncontrolled cell growth Absorbs nutrients needed by other cells, blocks nerve connections, and prevents organs from functioning.

Tumor Mass of cells from uncontrolled growth Benign tumor Noncancerous, does not spread Malignant tumor Cancerous, invades and destroys surrounding tissue Metastasis Spread of cancer cells.

Causes of Cancer Defects in genes that regulate cell growth and division p53 gene defect is common, doesn’t respond to growth signals Normally many defects or mutations are needed Sources of gene defects Smoking tobacco, radiation exposure, defective genes, and viral infection.

Cancer Treatments Tumors can be removed by surgery Tumors treated with targeted radiation Chemotherapy Use of compounds that kill or slow the growth of cancer cells.

The Rise and Fall of Cyclins Scientists measured cyclin levels in clam eggs as the cells went through the cell cycle. The data is shown on the following slide. Cyclins are continually produced and destroyed. Cyclin production signals cells to enter mitosis and their destruction signal cells to enter interphase.

Interpret Graphs How long does cyclin production last during a typical cell cycle in clams Infer During which part of the cell cycle dose cyclin production begin and how quickly is it destroyed Predict Suppose that the regulators that control cyclin production are no longer produced. What are two possible outcomes