Part III - The Eukaryotic Cell Cycle and Cancer

Part III. - The Eukaryotic Cell Cycle and Cancer (The Eukaryotic Cell Cycle and Cancer) DIRECTIONS: Go to Collea’s Corner and click on the: The Eukaryotic Cell Cycle and Cancer Follow the instructions as you proceed through the Click and Learn and answer the questions in the spaces below. Click on the “Background” tab on the right side. 1. Compare and contrast the reasons cell division is important for unicellular and multicellular organisms. Unicellular Multicellular _________________________________________________________________________________ • reproduction • reproduction (meiosis) • repair dead/damaged cells • growth/development _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ 2. Provide an example of why cell division remains important to an adult organism even after it is fully developed. Cell division remains important to an adult organism in order to replace cells _________________________________________________________________________________ that are dead or damaged. _________________________________________________________________________________ 3. What is the role of growth factors? Growth factors are molecular signal that cause cells to begin the cell cycle and _________________________________________________________________________________ divide. _________________________________________________________________________________ 4. Cells divide, differentiate, or die. What is differentiation? Differentiation is when cells specialize in structure and function through the _________________________________________________________________________________ expression of certain genes. _________________________________________________________________________________ 14 5. What is apoptosis? Explain its purpose. Apoptosis is programmed cell death. It purpose is to eliminate unnecessary cells and _________________________________________________________________________________ to kill off abnormal or damaged cells. _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ 6. Organisms maintain the right number of cells by regulating the cell cycle. What are “cell cycle regulators”? Cell cycle regulators are molecular signals that stimulate or halt cell division. _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ Watch the video clip of cell division in the small intestine. 7. Name the general location along the villus where the following processes occur: outside the villi Cell Division: _____________________________________________________________________ _________________________________________________________________________________ crypt ---> lumen Cell Differentiation: _______________________________________________________________ _________________________________________________________________________________ top of villi Apoptosis: ________________________________________________________________________ _________________________________________________________________________________ 15 8. Name one harmless result of too little cell division. hair loss _________________________________________________________________________________ 9. Name one harmless result of too much cell division. warts _________________________________________________________________________________ Click on “Cell Cycle Phases” in the center purple circle on the right and use the “Overview” information in the window on the left to answer the questions below. 10. List, in order, the four events we collectively call the “cell cycle.” Next to each event, write the correlating cell cycle phase name. G1 - First Gap Phase (1) ____________________________________________________________________ S - Synthesis Phase (2) ____________________________________________________________________ G2 - First Gap Phase (3) ____________________________________________________________________ M - Mitosis (4) ____________________________________________________________________ 11. In general, what is the purpose of a checkpoint in the cell cycle? ” The purpose of a checkpoint is to make sure the previous cycle went OK. _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ 12. What is one potential outcome when errors occur in this highly regulated cell cycle process? ” Cancer _________________________________________________________________________________ 16 Click on “Cell Cycle Regulators and Cancer” in the center purple circle on the right. Use the information under “Regulators Overview” in the window on the left to answer the questions below. 13. What type of protein that regulates the cell cycle is encoded by proto-oncogenes? stimulating protein ___________________________________________________ 14. What type of protein that regulates the cell cycle is encoded by tumor suppressor genes? inhibitory protein ___________________________________________________ CDKs: cyclin-dependent kinases 15. The most important cell cycle regulators are the __________________________________________. 16. What is a kinase, and what does it do? Kinases are enzymes that add a phosphate to other proteins in a process called _________________________________________________________________________________ phosphorylation. _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ 17. When are cyclin-dependent kinases (CDKs) present inside the cell during the cell cycle? Cyclin-dependent kinases (CDKs) present inside the cell during the cell cycle when _________________________________________________________________________________ they are bound to cyclins. _________________________________________________________________________________ _________________________________________________________________________________ 18. When are cyclins present inside the cell during the cell cycle? The presence of cyclins inside the cell during the cell cycle depend upon the _________________________________________________________________________________ phase as their concentration fluctuates (goes up and down) depending on the _________________________________________________________________________________ phase. _________________________________________________________________________________ 17 19. CDKs form molecular complexes with cyclins. What do activated CDK-cyclin complexes do? Activated CDK-cyclin complexes stimulate the cell cycle resulting in cell division. _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ (Amoeba Sisters: The Cell Cycle and Cancer) 18 Using the cell cycle diagram and both links in the center purple circle, complete the table below. Use bullet points and focus on major events that occur during each phase, checkpoint, and regulatory process. Complete the entire row before moving on to the next phase. Phase Major Events Checkpoint Events cell increases in size • prepares for DNA replication • G1 • • S DNA replication 2 complete sets of chromosomes • • No DNA damage sufficient resources (nutrients) Regulatory Processes Stimulating The phosphorylation of proteins by CDK-cyclins. Inhibitory (P53 Tumor Supressor) p53: • Halts the phase to allow for DNA repair. • Initiates cell death (apoptosis) if too much DNA damage is detected. Retinoblastoma (Rb): • Halts the phase if growth factor concentration is low. • No errors in DNA replication Stimulating • Increase in cyclin and CDK- cyclin complexes stimulate DNA replication. Inhibitory BRCA1: • Halts the phase to allow for DNA repair. • Initiates cell death (apoptosis) if too much DNA damage is detected. • • G2 cell keeps growing prepares for cell division No DNA damage Chromosome set complete • Enough cell components • • Stimulating: • CDK-cyclin complexes activate mitosis once DNA damage is repaired. Inhibitory P53: • Halts the phase to allow for DNA repair. • Initiates cell death (apoptosis) if too much DNA damage is detected. (p53 Guardian of the Genome) 19 Go to “Cell Cycle Phases” and click on “Interphase.” 20. Interphase alternates with mitosis. What happens during interphase and which phases does it include? During Interphase a cell grows and replicates its DNA. Interphase includes G1, S, _________________________________________________________________________________ and G2. _________________________________________________________________________________ _________________________________________________________________________________ Go to “Cell Cycle Phases” and click on “G0.” 21. The G0 phase is a resting or nondividing stage. What three factors determine whether a cell enters G0? when it receives a signal to differentiate, (1) ________________________________________________________________ when resources are insufficient (2) ________________________________________________________________ stage in development and the type of cell, (3) _______________________________________________________________ 22. Provide an example of a fully differentiated cell that is (a) permanently in G0 and (b) one that can leave G0 to progress through the cell cycle and divide again. neurons and muscle cells (a) ________________________________________________ liver (b) ________________________________________________ Click on “Cell Cycle Regulators and Cancer” in the center purple circle on the right. Then click on the “Cancer Overview” tab in the window to the left (right tab). 23. Cancer is the result of an improperly regulated cell cycle. Name two reasons why cells can form tumors. The two reasons why cells can form tumors are: _________________________________________________________________________________ • an improperly regulated cell cycle - too much cell division • too little cell death _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ 20 24. What causes uncontrolled cell division at the genetic level? At the genetic level, uncontrolled division of cells is caused by mutations affecting _________________________________________________________________________________ proteins that normally regulate the cell cycle. _________________________________________________________________________________ _________________________________________________________________________________ 25. Watch the video clip. At the cellular level in this example, explain what occurs if the APC gene is mutated. If the APC gene is mutated, cells have trouble differentiating and a tumor develops. _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ 26. Normally, proto-oncogenes stimulate the cell cycle. What do mutated proto-oncogenes/oncogenes cause? Proto-oncogenes create proteins that stimulate the cell cycle. Mutated proto_________________________________________________________________________________ oncogenes (oncogenes) increase stimulation of the cell cycle like putting a foot _________________________________________________________________________________ on the accelerator (gas pedal) increases the speed of a car. _________________________________________________________________________________ 27. Normally, tumor suppressor genes inhibit the cell cycle. What do mutated tumor suppressor genes cause? Tumor suppressor genes create proteins that normally INHIBIT the cell cycle. _________________________________________________________________________________ Mutated tumor suppressor genes can cause a loss of inhibition leading to _________________________________________________________________________________ uncontrolled cell division, which is like taking your foot off the brake pedal can _________________________________________________________________________________ also increase the speed of a car. 28. To cause cancer, proto-oncogenes require ( 1 or 2 ) (circle one) allele(s) to be mutated and are gain therefore considered ( dominant / recessive ) (circle one). This results in _____________ of function. 29. To cause cancer, tumor suppressor genes require ( 1 or 2 ) (circle one) allele(s) to be mutated and loss of function. are therefore considered (dominant / recessive) (circle one). This results in __________ 21 30. Watch the video clip. a. Using the gas pedal analogy, explain the impact on the cell cycle of a proto-oncogene versus oncogene. Proto-oncogenes create proteins that stimulate the cell cycle. Mutated _____________________________________________________________________________ proto-oncogenes (oncogenes) increase stimulation of the cell cycle like _____________________________________________________________________________ putting a foot on the accelerator (gas pedal) increases the speed of a car. _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ b. Using the brake pedal analogy, explain the impact on the cell cycle of one mutated tumor suppressor gene allele versus two mutated tumor suppressor gene alleles. Tumor suppressor genes create proteins that normally INHIBIT the cell cycle. ______________________________________________________________________________ Mutated tumor suppressor genes can cause a loss of inhibition leading to ______________________________________________________________________________ uncontrolled cell division, which is like taking your foot off the brake pedal can _____________________________________________________________________________ also increase the speed of a car. _____________________________________________________________________________ One mutation - cell cycle OK _____________________________________________________________________________ Two mutations - cell cycle proceeds inappropriately (too quickly) _____________________________________________________________________________ 22 Now that you have finished the Click and Learn, use your knowledge to answer the following questions. 31. p53 is a tumor suppressor gene, and some scientists refer to it as “the guardian of the genome.” a. Explain its normal role and why scientists would regard it as the “guardian of the genome.” p53 is a tumor suppressor gene that prevents (suppresses) tumor formation _________________________________________________________________________________ by halting cell division to allow for damaged DNA to be repaired or initiating _________________________________________________________________________________ cell death (apoptosis) if too much DNA damage is detected. In these ways, _________________________________________________________________________________ p53 acts as “the guardian of the genome.” _________________________________________________________________________________ b. Explain what happens to the cell cycle if both p53 alleles are mutated. If both p53 alleles are mutated, cell cycle inhibition is lost leading to uncontrolled cell _________________________________________________________________________________ division and tumor formation. _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ 32. Explain why people who inherit one mutated allele of the BRCA1 gene have a higher likelihood of developing cancer. People who inherit one mutated allele of the BRCA1 gene have a higher likelihood _________________________________________________________________________________ of developing cancer because the BRCA1 gene is responsible for helping to repair _________________________________________________________________________________ damages DNA. _________________________________________________________________________________ _________________________________________________________________________________ 33. Predict a potential outcome of a mutated MAD protein. A mutated MAD protein will allow the cell to finish the cell cycle but the daughter cells _________________________________________________________________________________ produced may have too many or too few chromosomes leading to a condition called aneuploidy. _________________________________________________________________________________ The is caused by a failure in the checkpoint that monitors the attachment of spindle (kinetochore) _________________________________________________________________________________ fibers to the centromere and the separation of chromosomes during anaphase. _________________________________________________________________________________ 23