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Share an overview of cancer projects within small groups to understand cell cycle regulation, cancer formation, symptoms, treatments, and environmental factors affecting telomeres. Learn about the discovery of cyclins, regulatory proteins, apoptosis, and how cancer cells disrupt normal cell growth. Explore common causes of cancer and treatments including surgery, radiation, and chemotherapy.
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Present Cancer Projects to small groups • Share an overview then fill in the graphic organizer • What is it? • How do you get it? • Who it affects? • Symptoms and Treatments
Learning Objectives • Refine model of the cell cycle to include its 3 specific checkpoints, chemical control signals, and growth factors • Explain how uncontrolled cell cycles result in cancer. • Understand and address the various stages of cancer, as well as terms such as apoptosis and telomeres.
Healing a Bone new bone cells • Cells at the edge of an injury are stimulated to divide rapidly. • As an injury heals, the rate of cell division slows.
The Discovery of Cyclins Scientists found a protein in a cell undergoing mitosis. They injected the protein into a non-dividing cell. A mitotic spindle started to form. Cyclins: proteins that regulate the cell cycle What does regulate mean? It seemed to “tell” the cells when it was time to divide, duplicate chromosomes or begin to enter a new phase of the cell cycle.
Regulatory Proteins Internal regulators: respond to events inside the cell let cell cycle proceed only when certain steps have already happened EX: Mitosis would not happen until all chromosomes are duplicated.
Regulatory Proteins External regulators: respond to events outside the cell EX: If you get cut, external regulators tell the cell to speed up the cell cycle so new cells can help fill in the gap where you got cut. As the cells begin to fill in the cut, regulators tell the cell cycle to slow down and return to normal processing. growth factors: wound healing and embryonic development
Programmed to die? Some cells die due to damage or injury but others are programmed to die. Apoptosis is what we call programed cell death. This can happen differently in various organisms to meet specific needs.
Cancer: Uncontrolled Cell Growth Cancer cells don’t respond to normal regulatory signals. Cell cycle is disrupted. Cells grow and divide uncontrollably. Some cancers do not respond to external regulators telling them to slow down when they are duplicating. Some cancers do not respond to internal regulators that make sure the cell has properly prepared to divide.
Cancer Formation: A Closer Look A cell begins to divide abnormally. Cells produce a tumor and start to displace normal cells and tissues. Cancer cells move to other parts of the body.
What Causes Cancer? In all cancers, control over has broken down. Cancer results from a defect in genes that control cell growth and division. the cell cycle
Cancer in Common • Many cancer cells have a defect in their p53 gene. This gene halts the cell cycle if chromosomes have not been properly replicated.
Telomeres • Telomeres are the caps at the end of each strand of DNA that protect our chromosomes, like the plastic tips at the end of shoelaces. • Telomeres are an essential part of human cells that affect how our cells age.
Telomeres Affected by Environmental Factors • Eventually, telomeres get too short to do their job, causing our cells to age and stop functioning properly. • Therefore, telomeres act as the aging clock in every cell. • Recent research has found that telomeres are shortened as we age, but telomeres can also be shortened by stress, smoking, obesity, lack of exercise and a poor diet • Research is focusing on pre-mature shortening of telomeres and its link to cancer
Treatments for Cancer Surgery to remove localized tumor Radiation to destroy cancer cell DNA Chemotherapy to kill cancer cells or slow their growth
Probe 1: • Why does a cell need a “check point” system to make sure things occur in the proper order? Describe why it is important.
Probe 2 • Describe a situation when a cell does not respond to an internal regulator and what problem it could cause.
Probe 3 • How are the growth of a tumor and the repair of a scrape on your knee similar? How are they different.
Homework • Page 288 Analyzing Data # 1, 2, 3 • Page 301 # 34, 35, 38, 39