Download Frequency of Crossing over lab

Columbia
HS
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Biolo
Sfudent's Name:
Class:
Lab
Lab Day:
Problem: How can the frequency of crossing over be estimated?
Procedure:
1. Set the web browser to www.campbellbiology.com. Sign in using 'oicohen" as the user id and
"Darwin08" as the password.
2. Select Chapter 13 (Meiosis and Sexual Cycles) from the pull down menu and then click on o'Case
Studies" at the left side of the screen.
3. Click on 'oHow can the frequency of crossing over be estimated?,,
Observations:
1. What is the name of the fungus studied in this activity?
Read through the text and then click on the images to review the various stages of meiosis.
After completing cytokinesis II, click on Next.
2. When during meiosis does crossing over occur?
3. How does crossing over change a chromosome?
Click on Next. Study the process of spore formation in Sordaria by clicking on the image.
4. How does the spore pattern on the asci indicate whether crossing over has occurred?
Click on Next and then continue on to the investigation. Analyze the spore patterns in the micrograph and
record your results in the table below.
Ascus Number
I
2
No Crossins Over
Crossing Over
J
4
5
6
7
8
9
t0
11
Total number of asci
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Anwer questions I and2 in Analysis.
Click on Next and go on to analyze the second smaller set of data. Answer questions 3 and 4 in analysis.
Analysis:
1.
What is the percent of crossover? (Number of asci with crossover, divided by the total number of asci x
100)?
2. For the sample shown, what is the map distance between the gene for spore color and the centromere
(Percent ofcrossovers divided by 2)?
3. In the second set of data, how many of these asci contain a sporo arrangement that resulted from
crossing over?
4. From this second small sample, calculate the map distance between the gene and centromere.
5. In what cell processes is mitosis involved? In what cell processes is meiosis involved?
6. In what type of cells does mitosis occur? In what type of cells does meiosis occur?
7. How many times do chromosomes replicate in mitosis? How many times do chromosomes replicate
in
meiosis?
8. How many cell divisions occur during mitosis? How many cell divisions occur during meiosis?
9. How many cells are formed by mitosis? How many cells are formed by meiosis?
10. What is the chromosome number
in cells formed by mitosis from parent cells with 10 chromosomes?
What is the chromosome number in cells formed by meiosis from parent cells with l0 chromosomes?
11. In mitosis, are daughter cells identical to or different than parent cells? In meiosis, are daughter cells
identical to or different than parent cells?