UMUC Biology 102/103 Lab 5: Meiosis

Lab 5: Meiosis

Pre-Lab Questions

1. What major events occur during the interphase?

Answer: The cell functions at its job, and prepares for mitosis by collecting resources and duplicating organelles (G1) and genetic content (S), then creating proteins needed for nuclear division (G2).

2. A person, residing in a location where they are exposed to the sun often, develops a mutation in some of their skin cells resulting in cancer. Consider whether their offspring will be born with the same mutation. Use scientific evidence to support your answer.

Answer: It would be highly unlikely that the person’s offspring will be born with the same skin cancer mutation because the mutation occurred in the person’s skin cells. Skin cells are somatic cells (body cells) and are not involved in meiosis or reproduction. For the mutation to be passed on to the offspring, a sex cell (sperm or egg) would have to carry the mutation.

The other questions that will be answered:
Experiment 1: Following Chromosomal DNA Movement through Meiosis

Data Tables and Post-Lab Assessment

Trial 1 – Meiotic Division Beads Diagram:

Prophase I

Metaphase I

Anaphase I

Telophase I

Prophase II

Metaphase II

Anaphase II

Telophase I

Cytokinesis

Trial 2 – Meiotic Division Beads Diagram:

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: a)Sperm Cell: b)Egg Cell: c)Daughter Cell from Mitosis: d)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

Data Tables and Post-Lab Assessment

 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 a normal cell cycle?
5. What are HeLa cells? Why are HeLa cells appropriate for this experiment?