Task 12
Mitosis Project Investigation
Based on your research and area of interest, describe the various components of your project.
Purpose or Driving Question (Identify variables and units of measurement)
How do organisms grow and develop? How is the cell cycle regulated?
They grow because of cell replication, or mitosis.They are regulated by cyclin dependant kinases and cyclins. If, for some reason, the cell is too overwhelmed and grows irregularly, then that action leads to cancer.
Variables:
Independent Variable- the mitosis phases
Dependent Variable- resulting number of chromosomes on each phase
Control- other components and processes that remain constant during actual mitosis phase
Constants- nucleus
Procedure: List the steps in your experimental plan. A labeled diagram of the setup is essential.
PART 1: • Cut a length of string two meters long. This string represents the amount of DNA in a human cell if all of the DNA molecules were placed end-to-end in a straight line.
• Where is DNA found within a cell?
• If the long string had to fit into a very small compartment, what would you do to the string to make it more compact?
• How does this relate to the organization of DNA within a cell?
• What is the difference between chromatin and chromosomes?
• Cells spend a lot of time in "interphase." What happens in a cell during this time?
• Sometimes a cell in interphase prepares for cell division. One type of cell division is called mitosis. What is the purpose of mitosis?
• Use pop beads or pipe cleaners to represent chromosomes. Use tape or string to represent the cellular membrane and nuclear membrane. Place the chromosomes in the nucleus. How many chromosomes are in your model cell?
• If, at the beginning of mitosis, chromosomes consist of two identical chromatids, what must happen to DNA prior to mitosis?
• What is a centromere and what purpose does it serve?
• If the cell has prepared itself to divide by mitosis, it enters prophase (the first official stage of mitosis). What happens during prophase? Simulate prophase in your model cell.
• Simulate metaphase in your model cell. What is the most important feature of metaphase?
• Simulate anaphase. In your model, you are physically moving the chromosomes within the cell. In a real cell, how are chromosomes moved?
• During anaphase, is a nucleus present in the cell? Why or why not?
• Telophase follows anaphase. Simulate telophase and describe what happens during this phase. (This is the last phase of mitosis but the phases are not distinct; the process is continuous over time.)
• Separation of the genetic material is officially complete when a new nuclear membrane forms around each set of chromosomes. How many chromosomes are present in each
new nucleus? How does this compare to the "parent" cell you began the simulation
with?
• To form two "daughter" cells, cytokinesis must occur. What is cytokinesis? How can
you simulate this in your model cell?
• Onion root tip cells and whitefish blastula cells are often viewed with a microscope to
help students understand what the phases of mitosis look like in real cells. Why would
there be a lot of cells undergoing mitosis in a root tip and in a blastula?
Hypothesis: Describe what you think will happen and why. You may base your hypothesis on your research or your own observations/experience.
I hypothesize that the cell will spend more time in the interphase, maybe more than 50% that the other stages because of my previous knowledge of the process being where most activities happen.
Materials: Identify all the equipment and chemicals you will need to implement your investigation.
1If a kit is not available, pipe cleaners can be used as model chromosomes.
Safety: Look up the MSDS of every chemical that you intend to use and underline the hazardous chemicals listed in the materials section. Describe specific safety precautions that you will take to ensure your personal safety as well as the safety of others and the environment. Students planning experiments involving environmental sampling or living organisms must specify measures used to ensure safety for themselves as well as the environment/organisms used.
Pay attention to the following maintenance recommendations, and add these important safety
precautions to your normal laboratory procedures:
♦ Handle living organisms carefully. Be sure to follow the guidelines for proper care that are shipped
with the organisms.
♦ If you grow and prepare onion root tips for microscopic analysis, wear safety goggles when
performing the staining procedure and work in a well-ventilated area or fume hood.
Observations and Data: Draw a tentative data table showing intervals/trials and units of measurement.
Although there aren’t necessarily any correlations, the amount of cells on the interphase of the cell cycle were increasingly higher than the cells in the other stages. In my research paper, I’ve stated that cells spend a significant amount of time in the interphase, where all the growth and development happen. They replicate organelles and DNA making this cycle a major contributor for cellular reproduction. From this we can conclude that the cell spent most of its time of its five day span in the interphase.
Calculations, Formulas, & Graph Layouts: Specify any formulas, sample calculations and approximate layout of graph with labeled axes and units.
To find out the average time that each cell process takes up in a 24 hour cycle, if cells were to reproduce in 24 hours, then you would have to multiply the percentage of cells in each stage, as a decimal, and multiply it by 24.
The amount of cells in the interphase stage of the cell cycle is about 14.5 hours, in the prophase stage 2.7 hours, in the metaphase stage about 2.3 hours, in the anaphase about 1.9 hours, and finally in the telophase about 1.7 hours.
Background Information
Research your project topic based on the driving question above. Use any resources available to research background information that will help you to complete your project.
Below is a list of key words that may be helpful when doing your background research.
Research/References: List 5 references that you used to learn about the scientific concepts related to your experiment and to figure out what is likely to happen in your investigation. Please use standard bibliographic format as learned in your English class.
1. Raven PH, Evert RF, Eichhorn SE. (2005). Biology of Plants (7th Edition). New York: W.H. Freeman Company Publishers
2. Albertson R, Riggs B, Sullivan W. (2005). “Membrane traffic: a driving force in cytokinesis”. Trends in biology 15.
3. Chang G, Gen T. (2003). “The mitotic checkpoint: a signaling pathway that allows a single unattached kinetochore to inhibit mitotic exit.” Process in Cell Cycle Research 5.
4. Maiato H, DeLuca J, Salmon E, Earnshaw W. (2004). Journal of Cell Science.
5. “Chan G, Liu S, Yen T. (2005) Trends in Cell Biology.
Extension and Synthesis Questions
The answers to the following questions will guide you to further critical thinking about your project topic and will build knowledge to help answer questions your classmates may ask when you make your presentation.
1. The growth and development from an embryo to a teenager can be attributed to mitosis and cell differentiation. Even as an adult, mitosis will continue in the body. For example, you shed dead skin cells every day. These cells are replaced by mitosis occurring in the skin tissue. Will all skin cells have the same genetic information (DNA)? Why or why not? What about your skin cells and heart tissue cells - do they have the same DNA?
Since they’re still cells, yes, they do have DNA. However, their DNA will wear off as the cell sheds. They’re more temporary, so they’re different than other vital organs like the heart tissue cell.
2. How would you summarize the process and purpose of mitosis in three or four sentences to someone else?
Mitosis is the process in which cells grow and reproduce. They have 5 steps, the interphase, prophase, metaphase, anaphase, and the telophase; 6 if you include cytokinesis. Mitosis is very important for cell growth, eventually reaching an organism level, so for an organism to grow, you need mitosis.
3. The image to the right shows a "classic" picture used to illustrate chromosomes. Do chromosomes always look like this? Why or why not?
They typically do look like that. That is the standard form and shape of a chromosome. However, they might be affected by viruses which can lead to a change in shape.
4. If you view cells with a microscope, are you more likely to see the cell's genetic material when the cell is in interphase or when it is in metaphase? Explain your answer.
Probably in the interphase, since it is where the cells spends the most time and where all the growth happens.
5. Why is it important for chromatin to condense into chromosomes at the beginning of mitosis?
Because the chromosomes need to duplicate to form two long, thin strands (sister chromatids) that will split up in a single chromosome later on in the anaphase.
6. After telophase, why does cytokinesis need to occur to complete cell division? Does this process happen in the same way in plant cells and animal cells? Explain your answer.
Cytokinesis is important for reproduction. This is where the two cells officially split and are ready for other cells to reproduce. In plant and animals cells are different however.
In plants, the cell plate cuts the cytoplasm in half, which makes the cell place separate its walls for two new cells.
In animals, the membrane works like a belt. It goes inward until the cytoplasm breaks in half.
7. How are stem cells different from other cells? What are some examples of stem cell research?
They are quite different, one of the differences is that they have more reproduction chances, whereas other cells are more limited. An example of this are the blood making cells from the bone marrow that generate blood to supply the body.
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