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GUIDED READING 10.3 (GEISLER) Name ___________________________ Class ________ Date: _____________ 1. How are cancer cells different _______________________________________? 2. Not all cells move through the cell cycle _______________________________________. In the human body, most muscle cells and nerve cells ______________________________________ ______________once they have developed. 3. In contrast, the cells of the ______________________________________________, and cells in the bone marrow that make blood cells, __________________________________ __________ throughout life. 4. Cells in a Petri dish will _______________________________________ until they come _______________________________________with other cells. 5. What would happen if the cells _______________________________________? 6. If cells are removed from the _______________________________________, however, the cells bordering the open space will begin dividing _____________________________ __________the empty space. These experiments show that the controls on cell growth and cell division can be _______________________________________. 7. Scientists can observe the effects of _______________________________________ in the laboratory by placing some cells in a Petri dish ________________________________________. 8. Most cells will grow until they form a thin layer _________________________________________ the dish, as shown in Figure 10-7. Then, the cells stop growing. 9. When cells come into contact with other cells, they _____________________________________ __________. 10. When an injury such as a cut in the skin or a break in a bone occurs, cells at the edges of the injury are _______________________________________ rapidly. This action produces new cells, starting _______________________________________. Cell Cycle Regulators 11. There are two types of regulatory proteins: those that occur _____________________________ __________ and those that occur outside the cell. 12. For many years, biologists searched for a substance that might ___________________________ __________________ —something that would "tell" cells when it was ______________________ ___________________ their chromosomes, or enter another phase of the cycle. 13. _______________________________________, including Tim Hunt of Great Britain and Mark Kirschner of the _______________________________________, discovered that cells in mitosis contained a protein that when injected into ___________________________________________, would cause a mitotic spindle to form. GUIDED READING 10.3 (GEISLER) Name ___________________________ Class ________ Date: _____________ 14. They decided to call this protein ________________ because it ________________________ _______________ the cell cycle. 15. More recently, dozens of _______________________________________ have been discovered that also help to regulate the cell cycle. 16. _______________________________________ allow the cell cycle to proceed only when certain processes have happened inside the cell. 17. _______________________________________ to events outside the cell are called external regulators. 18. External regulators direct cells to_______________________________________ the cell cycle. _______________________________________ among the most important external regulators. Molecules found on the surfaces _______________________________________ often have an opposite effect, causing cells to _______________________________________ their cell cycles. 19. Proteins that respond to events inside the cell are called _________________________________ ____________________. 20. Another regulatory protein prevents a cell _______________________________________ until all its chromosomes are attached to _______________________________________. 21. A _______________________________________ is removed from a cell in mitosis. The sample is injected _______________________________________ in G2 of interphase. As a result, the second cell enters mitosis. Uncontrolled Cell Growth 22. What causes the _______________________________________ that characterizes cancer? The various forms of cancer have many causes, including _________________________________ _____________________________________________. 23. _______________________________________, have one thing in common: The control over the cell cycle _______________________________________. 24. _______________________________________ do not respond to the signals that regulate the _______________________________________. 25. Why is cell growth ________________________________________________? The principal reason may be that the consequences of _______________________________________ in a multicellular organism are very severe. 26. _______________________________________ do not respond to the signals that regulate the _______________________________________. As a result, they divide uncontrollably and form masses of cells called tumors that can damage the surrounding tissues. GUIDED READING 10.3 (GEISLER) Name ___________________________ Class ________ Date: _____________ 27. An astonishing number of cancer cells have a _______________________________________, which normally halts the cell cycle until all chromosomes ______________________________ ______________. _______________________________________ p53 genes cause the cells to lose the information needed to respond to signals that would ________________ ______________ _________________________________. Stem Cells: Promises and Problems 28. _______________________________________, every cell was produced by mitosis from a small number of cells _______________________________________. 29. Stem cells are _______________________________________ that have the potential to differentiate—to become specialized in _______________________________________ —into a wide variety of cell types. 30. Stem cells in the _____________________________________________________, produce more than a dozen types of blood cells, replacing those lost ___________________________________ ___________________________________________. Stem Cells in Medicine 31. _____________________________________________________________________________ solution to this problem. Recently, researchers have found that___________________________ ________________ can reverse the effects of brain injuries in mice. There is hope that the same __________________________________________ and that stem cells might be used to reverse ______________________________________________________________________________. 32. It also may be possible to use stem cells to _______________________________________, to replace heart valves, and to reverse _______________________________________. 33. For example, the body is not able to produce new neurons to repair ___________________ ___________________________________________________, such as those that cause paralysis. Because of this, at present, there is no way for doctors __________________________ ________________________________________________ to people who are paralyzed. Sources of Stem Cells 34. However, _______________________________________ cells are taken from human embryos these techniques raise _____________________________________________________________. Because of such issues, _______________________________________________ is highly controversial. 35. Researchers have found that ________________________________________________________ ______ cells sometimes can be grown from adult, _______________________________________. GUIDED READING 10.3 (GEISLER) Name ___________________________ Class ________ Date: _____________ 10-3 Section Assessment (REQUIRED; please write all answers in complete sentences.) 1. 2. 3. 4. 5. What chemicals regulate the cell cycle? How do they work? What happens when cells do not respond to the signals that normally regulate their growth? How do cells respond to contact with other cells? Why can cancer be considered a disease of the cell cycle? Critical Thinking/Formulating Hypotheses: Write a hypothesis about what you think would happen if cyclin were injected into a cell that was in mitosis. Designing an Anticancer Drug (Alternative Assessment; extra credit if completed) Imagine that you are developing a drug that will inhibit the growth of cancer cells. Use your knowledge of the cell cycle to describe how the drug would target and prevent the multiplication of cancer cells. Use the Internet to compare your anticancer drug with those currently in use.