Unit 5: Cell Growth and Development 5.3 Control of the Cell Cycle
Not all cells move through the cell cycle at the same rate. Example: Most nerve cells do not divide once they are developed Example: Blood cells may complete a cycle every few hours Not all cells move through the cell cycle at the same rate.
The cell cycle is controlled by cyclins and other proteins Internal regulatory proteins: Proteins that allow the cell cycle to proceed only when certain events have occurred within the cell Cyclin: A type of protein that regulates the cell cycle Regulatory Proteins
The cell cycle is controlled by cyclins and other proteins External regulatory proteins: Proteins that respond to events outside the cell to speed up or slow down the cell cycle Growth factors: A type of protein that stimulates growth and division of cells during embryonic development and wound healing Regulatory Proteins
Cell growth and division is controlled by proteins and 3 checkpoints Cell Growth (G1) Checkpoint: If the cell is healthy and large enough, it will divide. If conditions are not favorable, it will not divide DNA Synthesis (G2) Checkpoint: DNA replication is checked by DNA repair enzymes Once checked, cell will prepare for mitosis Mitosis Checkpoint: Triggers the exit of Mitosis and the entering of G1 (Growth Stage 1). Cell growth and division is controlled by proteins and 3 checkpoints
As new cells are produced, many others must die As new cells are produced, many others must die. This happens in two ways: By accident, due to damage or injury to a cell “Programmed” to die
Apoptosis: A series of controlled steps leading to the self- destruction of a cell that has been programmed to die. Apoptosis plays a key role in development by shaping the structure of tissues and organs in plants and animals.
The human hand is shaped the way it is because cells between the fingers die by apoptosis during tissue development Example
Cancer Uncontrolled cell growth Caused by defects in the genes
Cancer and the Cell Cycle Discussion Questions Explain the factors that control normal cell division. Explain what happens when normal cell division is disrupted. Compare and contrast the terms carcinogen and mutagen. Use the terms TUMOR SUPPRESOR GENES, PROTONCO GENES, and MUTATION to explain how the cell cycle relates to cancer. Cancer and the Cell Cycle Discussion Questions