Biol 241 homework
Professor: Greg Crowther
1. Compare and
contrast the reasons cell division is important for unicellular and multicellular organisms. Cell division is the method in which single celled organisms reproduce. Cell division allows multi-cellular to grow and repair dead or damaged cells
2. Provide an example of why cell division remains important to
an adult organism even
after it isfully developed. Some cells divide to heal wounds such as cuts or broken bones.
3. What is the role of growth factors? Growth factors send molecular signals that tell cells to divide.
divide, differentiate, or
die. What is differentiation? Differentiation is when a cell stops dividing to perform a special function or to change shape.
5. What is apoptosis? Explain its purpose. Apoptosis is a process that eliminates unnecessary cells during development and destroys damage or unhealthy cell in a mature organism.
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 stop cell division, tell cells to differentiate, or cause cell death.
7. Watch the video clip of cell division in
the small intestine. Name the general location
along the villus where the following processes occur: Cell Division: _The crypt
Cell Differentiation: _The lumen
Apoptosis: _The top of the villus
8. Name one harmless result of too little cell division. Hair loss is the result of too little cell division
9. Name one harmless result of too much cell division. Warts can be caused by too much cell division
in order, the four events we collectively
“cell cycle.” Next to each event, write the correlating cell cycle phase name. a. _G1 phase
b. _S phase
c. _G2 phase
d. _M phase
11. In general, what is the purpose of a checkpoint in the cell cycle? The checkpoints in the cell cycle allow the cell to appraise the health of the cell and check for any errors.
12. What is one
potential outcome when errors
occur in this highly regulated cell cycle process? Mutations that occur during the cell cycle process have the potential to cause cancer.
13. What type of protein that regulates the cell cycle is encoded
by proto-oncogenes? Stimulator proteins are encoded by proto-oncogenes.
14. What type of protein that regulates the cell cycle is encoded
by tumor suppressor genes? Inhibitor proteins are encoded by tumor suppressor genes.
cell cycle regulators are
the cyclin-dependent kinases.
16. What is a kinase, and what does it do? “Kinases are enzymes that add a phosphate to other proteins to activate or inhibit their function”. (The Eukaryotic Cell Cycle and Cancer)
17. When are cyclin-dependent
(CDKs) present inside the cell during the
cell cycle? CDKs are always present in the cell, they become active when they bind to other proteins called cyclins. Cyclin concentration in the cell goes up and down, depending on the phase of the cycle.
18. When are cyclins present inside the cell during the cell cycle? Cyclin concentrations rise at the G1, S, and lG2 phases.
19. CDKs form molecular complexes with cyclins. What
do activated CDK-cyclin
complexes do? Activated CDK-cyclin complexes add a phosphate to other proteins to activate or inhibit their functions.
20. Go to “Cell Cycle Phases” and click on “Interphase.” The interphase alternates with mitosis. What happens during
which phases does it include? The cell grows and replicates DNA during interphase. Interphase encompasses G1, S, and G2 phases.
21. Go to “Cell Cycle Phases” and click on “G0.” The G0 phase is
a resting or no dividing
stage. What three factors determine whether a cell enters G0? A cell enters G0 phase if it receives signals to differentiate or if it lacks resources...
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