Anatomy

”2. What stage were most of the onion root tip cells in? Why does this make sense? ”

”3. As a cell grows, what happens to its surface area : volume ratio? (Think of a balloon being blown up). How is this changing ratio related to cell division? ”

”4. What is the function of mitosis in a cell that is about to divide? ”

”5. What would happen if mitosis were uncontrolled? ”

”6. How accurate were your time predictions for each stage of the cell cycle? ”

”7. Discuss one observation that you found interesting while looking at the onion root tip cells.”

Experiment 2: Tracking Chromosomes Through Mitosis

Once you have completed the digital exercise, select the “Results Table” button at the bottom right-hand corner of the screen and select the “Generate PDF” button at the top of the following screen. Insert your download into this document by selecting the Insert > Object > Text from file. Resize if necessary.

Post-Lab Questions

· How many chromosomes were present before mitosis?

· How many chromosomes did each of the daughter cells contain after mitosis?

· Cite an example of a type of cell that undergoes mitosis. Why is it important for each daughter cell to contain information identical to the parent cell?

· Human skin cells divide at a higher rate than neurons (nerve cells). Hypothesize why this may be.

· Hypothesize what would happen if the sister chromatids did not split equally during anaphase of mitosis.

Experiment 3: Following Chromosomal DNA Movement through Meiosis

Part 1: Once you have completed the digital exercises, take screenshots and insert them below. Resize if necessary.

Table 5a (Meiosis I):

Table 5b (Meiosis II):

Parts 2, 3, and 4: Once you have completed the digital exercise, select the “View Data Table” button at the bottom left-hand corner of the home screen. Review your table. If you would like to make any changes, select the “Return” button in the bottom right-hand corner. If you are satisfied with your answers, take a screenshot and insert it below. Resize if necessary:

Post-Lab Questions

· How did crossing over affect the genetic content in the gametes? Use your results to support your answer.

· What is the ploidy of the daughter cells at the end of meiosis I? What about at the end of meiosis II?

· List two differences between meiosis I and meiosis II.

· Based on your observations in the digital exercise, what can you conclude about the severity of nondisjunction that occurs in meiosis I as opposed to meiosis II?

·

· Why is it necessary to reduce the number of chromosomes in gametes, but not in other cells?

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· Blue whales have 44 chromosomes in every cell. Determine how many chromosomes you would expect to find in the following: ”

”Sperm Cell: ”

”Egg Cell: ”

”Daughter Cell from Mitosis: ”

”Daughter Cell from Meiosis II: ”

Experiment 4: The Importance of Cell Cycle Control

Data:

1. 2. 3. 4. 5.

Post-Lab Questions

”1. Record your hypothesis from Step 1 in the Procedure section here. ”

”2. What do your results indicate about cell cycle control? ”

”3. Suppose a person developed a mutation in a somatic cell which diminishes the performance of the body’s natural cell cycle control proteins. This mutation resulted in cancer yet, but was effectively treated with a cocktail of cancer-fighting techniques. Is it possible for this person’s future children to inherit this cancer-causing mutation? Be specific when you explain why or why not. ”

”4. Why do cells which lack cell cycle control exhibit karyotypes which look physically different than cells with normal cell cycle. ”

”5. What are HeLa cells? Why are HeLa cells appropriate for this experiment? ”

”6. Research the function of the protein called p53. What does this function do? Explain how it can affect cell cycle control. ”

”7. What is the Philadelphia chromosome? How is this chromosome related to cancer? Identify how this chromosome appears physically different on a karyotype than it appears on a karyotype of normal chromosomes. ”