University:
Yeshiva University
Course:
3207C | Cell Biology
Academic year:

2019
Views:

32

Pages:

2
Author:

Elsie W

Meiosis How does sexual reproduction lead to genetic variation? Why? Cells reproduce through mitosis to make exact copies of the original cell. This is done for growth and repair. Sexually-reproducing organisms have a second form of cell division that produces reproductive cells with half the number of chromosomes. This process is called meiosis, and without it, humans, oak trees, beetles, and all other sexually-reproducing organisms would be vastly different than they are today. Model 1 - Meiosis I Homologous chromosomes come together to form a tetrad Cell from the sex organs (ovaries/testes in animals) during Interphase I Early Prophase I Late Prophase I Telophase I Metaphase I Anaphase I 1. According to Model 1, in what type of organs are the cells that enter meiosis I found? 2. Considering what you already know about mitosis in cells, what event must take place during interphase before a cell proceeds to division? 3. What two structures make up a single replicated chromosome? 4. In Model 1, how many replicated chromosomes does the cell contain during prophase? Read This! Alleles are alternative forms of the same gene. For example, gene A may contain the information for fur color. One allele ''A" may result in white fur, while the alternative allele "a'' may result in black fur. Homologous chromosomes are chromosomes that contain the same genes, although each chromosome in the homologous pair may have different alleles. 5. At which stage in meiosis I do the pairs of homologous chromosomes come together? 6. Once the chromosomes have formed a pair, what are they called? 7. At the end of meiosis I , two cells have been produced. How many replicated chromosomes are in each of these cells? 8. Cells with a full set of chromosomes are referred to as diploid or 2n, whereas cells with half the chromosomes are haploid or n. At which stage(s) of meiosis I are the cells diploid and at which stage(s) are they haploid? 9. Which of the statements below correctly describes the relationship between the cells at the end of telophase I and the original cell? a. The new cells have one copy of all of the genetic information in the original cell. b. The new cells have two copies of all of the genetic information in the original cell. c. The new cells have one copy of half of the genetic information in the original cell. d. The new cells have two copies of half of the genetic information in the original cell.