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 DEVELOPMENT10.3 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 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.

1. Interpret Graphs How long does cyclin production last during a typical cell cycle in clams

2. Infer During which part of the cell cycle dose cyclin production begin and how quickly is it destroyed

3. Predict Suppose that the regulators that control cyclin production are no longer produced. What are two possible outcomes