Lab 5 – Meiosis
Lab 5 – Meiosis
Before you begin your work, please read very carefully the Introduction in the Lab Manual and study Figure 2 closely. Then answer the two pre-lab questions as thoughtfully and in depth as you can.
Experiment 1: Following Chromosomal DNA Movement through Meiosis
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Order Paper Now(a) Part 1: You will simulate meiosis with two pairs of homologous chromosomes by using snap beads (they are in your kit). Then follow the instructions by simulating meiosis I and meiosis II. You may either photograph each stage and paste it into Part I – Meiotic Division Beads Diagram, or, you may draw each stage directly onto the lab page. Be sure to use two different colors.
(b) Part 2: This time, you will begin again with two sets of homologous chromosomes, but then make crossing-over happen for each set. Following that, you will then go through meiosis I and II again and draw, or photograph, each step carefully. You need to write down the number of chromosomes for each cell and stage in Part 1 and Part 2. – Explain the differences in outcome between Part 1 and Part 2.
You will find several questions at the end of experiment 1; please answer them all. You should remember that each and every species has different numbers of chromosomes. For example, humans have 23 pairs, that is, 46 total number of chromosomes. Mice have 40 chromosomes, dogs have 78, giraffes have 30, and some plants have over 200 chromosomes. The number of chromosomes found in the cells of individualspecies, are the result of their individual evolutionary history.
Experiment 2: The Importance of Cell Cycle Control
This will allow you to do some real-life research based on karyotypes. When you formulate your hypothesis please remember that it should be a brief, reasonable statement of expected outcomes. Please copy and paste five actual and complete karyotypes. Then answer the questions carefully.
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Your Full Name:
UMUC Biology 102/103
Lab 5: Meiosis
INSTRUCTIONS:
· On your own and without assistance, complete this Lab 5 Answer Sheet electronically and submit it via the Assignments Folder by the date listed in the Course Schedule (under Syllabus).
· To conduct your laboratory exercises, use the Laboratory Manual located under Course Content. Read the introduction and the directions for each exercise/experiment carefully before completing the exercises/experiments and answering the questions.
· Save your Lab 5 Answer Sheet in the following format: LastName_Lab5 (e.g., Smith_Lab5).
· You should submit your document as a Word (.doc or .docx) or Rich Text Format (.rtf) file for best compatibility.
Pre-Lab Questions
1. Compare and contrast mitosis and meiosis.
2. What major event occurs during interphase?
Experiment 1: Following Chromosomal DNA Movement through Meiosis
Data Tables and Post-Lab Assessment
Trial 1 – Meiotic Division Without Crossing Over Beads Diagram:
Take pictures of your beads for each phase of meiosis I and II without crossing over. Include notes with your name, date and meiotic stage on index cards in the pictures. Please use the lowest resolution possible so that your file does not become too large to submit.
Insert pictures here:
Prophase I
Metaphase I
Anaphase I
Telophase I
Prophase II
Metaphase II
Anaphase II
Telophase I
Cytokinesis
Trial 2 – Meiotic Division with Crossing Over Beads Diagram:
Take pictures of your beads for each phase of meiosis I and II with crossing over. Include notes with your name, date and meiotic stage on index cards in the pictures. Please use the lowest resolution possible so that your file does not become too large to submit.
Insert pictures here:
Prophase I
Metaphase I
Anaphase I
Telophase I
Prophase II
Metaphase II
Anaphase II
Telophase I
Cytokinesis
Post-Lab Questions
1. What is the ploidy of the DNA at the end of meiosis I? What about at the end of meiosis II?
2. How are meiosis I and meiosis II different?
3. Why do you use non-sister chromatids to demonstrate crossing over?
4. What combinations of alleles could result from a crossover between BD and bd chromosomes?
5. How many chromosomes were present when meiosis I started?
6. How many nuclei are present at the end of meiosis II? How many chromosomes are in each?
7. Identify two ways that meiosis contributes to genetic recombination.
8. Why is it necessary to reduce the number of chromosomes in gametes, but not in other cells?
9. Blue whales have 44 chromosomes in every cell. Determine how many chromosomes you would expect to find in the following:
i. Sperm Cell:
ii. Egg Cell:
iii. Daughter Cell from Mitosis:
iv. Daughter Cell from Meiosis II:
10. Research and find a disease that is caused by chromosomal mutations. When does the mutation occur? What chromosomes are affected? What are the consequences?
11. Diagram what would happen if sexual reproduction took place for four generations using diploid (2n) cells.
Experiment 2: The Importance of Cell Cycle Control
For each of the five abnormalities you find online, copy and paste a picture of it (and be sure to cite the URL for the picture)—you will not be photographing your own results for this section of lab, because you’re doing your research online for the questions below.
Data Tables and Post-Lab Assessment
1. [paste in your online picture and cite the URL]
2. [paste in your online picture and cite the URL]
3. [paste in your online picture and cite the URL]
4. [paste in your online picture and cite the URL]
5. [paste in your online picture and cite the URL]
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, 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?
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