2014

Investigation 7: Cell Division: Mitosis and Meiosis

(Please follow the format and order listed below, this lab my be sent electronically or in paper.

I. Background Information ( please use at least 2 references in this section, one can be your lab manual and the other can be your textbook, but include the page number)

1. Describe the events in the cell cycle and how these events are controlled.

2. Explain how DNA is transmitted to the next generation via mitosis.

3. Explain how DNA is transmitted to the next generation via meiosis followed by fertilization.

4. Explain how meiosis and crossing over-leads to increased genetic diversity, which is necessary for evolution.

Part I- Modeling Mitosis- Model and label mitosis and meiosis, take a photo of each phase. Answer the following questions:

1. If a cell contains a set of duplicated chromosomes, does it contain any more genetic information than the cell before the chromosomes were duplicated? Explain.

2. What is the significance of the fact that chromosomes condense before they are moved?

3. How are the chromosome copies, called sister chromatids, separated from each other?

4. What would happen if the sister chromatids failed to separate?

Part II- Modified- Counting cells in Interphase and in mitosis- see table 1- page 88

Onion Root tip cell phase data

Number of cells
Tip / Interphase / Mitosis / Total
1
2
3
Your total
Class Total

Part III- Loss of Cell Cycle Control in Cancer

Using the powerpoint presentation, your lab manual and an internet search to , relating to Case 1 HeLa cells and answer the following questions:

1. What are cyclins and cyclin dependent kinases? What do these proteins do in a cell?

2. How are normal cells and cancer cells different from each other?

3. What are the main causes of cancer?

4. What goes wrong during the cell cycle in cancer cells?

5. What makes some genes responsible for an increased risk of certain cancers?

6. Do you think that the chromosomes might be different between normal and cancer cells?

7. How does infection with human papillomavirus virus (HPV) increase the risk of cervical cancer?

Case 2 : Philadelphia Chromosomes

Use the internet, your lab manual and your textbook to research the following questions:

1. What happens in a normal cell if the DNA has mutations?

2. What would happen if cells with mutated DNA replicated?

3. How do cells monitor DNA integrity?

4. How are the chromosomes different in the cancer cells compared to normal cells?

5. How could these differences lead to cancer?

Part V- Meiosis and Crossing Over in Sordaria

Procedure: Describe what you did from the beginning (inoculation to counting the Asci)

Data: Include pictures of your final product.

Analyze the class data table.

Page 95 lab manual

Table 3. Analysis of Results - Total Class results

Number of Asci Showing 4:4 Pattern / Number of Asci showing crossing over / Total # of Asci / % Asci Showing Crossover Divided by 2 / Gene to Centromere Distance (map units)
Cindy 17 / 11 / 28
Ashley 20 / 11 / 31
Wajiha 19 / 12 / 31
Laura 33 / 0 / 33
Kassie 37 / 11 / 48
Josh and Chris 18 / 11 / 29
Lotta
Shreyas
Christina

Questions:

1. Why did you divide the percentage of asci showing crossover (recombinant ) by 2?

2. The published map distance between the spore color gene and the centromere is 26 map units. How did the class data compare with this distance?

3. How can you account for any disparities between the class data and the published data?

4. Illustrate in words or diagrams what happened during meiosis to produce the results you found.

5. Do you think the Philadelphia chromosome is a result of crossing over as seen in this part of the investigation or some other chromosomal abnormality? Explain your answer.

Conclusion: Due to all of the questions in the lab your will not be required to write an additional conclusion.