1. Chapter 7 Meiosis

2. Meiosis Forms haploid gamete or spore cells
Type of cell division that halves the number of chromosomes
Creates 4 genetically different cells

3. Steps to Meiosis I
Prophase I – Chromosomes condense, nuclear membrane breaks down, homologous chromosomes pair up and crossing-over occurs
Crossing-over – when homologous chromosome pairs exchange genetic material

5. Metaphase I
Pairs of homologous chromosomes line up together (like holding hands)

6. Anaphase I
Pairs separate (NOT CHROMATIDS) and are pulled to opposite ends of the cell

7. Telophase I Chromosomes gather at the poles Cytokinesis then occurs
DNA does not replicate to start Meiosis II

8. Prophase II
New spindle forms

9. Metaphase II
Chromosomes line up along the middle of the cell (just like Mitosis)

10. Anaphase II
Centromeres divide, chromatids separate, and move towards the poles of the cell

11. Telophase II – Nuclear membrane forms around each set of chromosomes
Cytokinesis occurs

12. http://highered. mcgraw-hill

14. Genetic Diversity Meiosis contributes to genetic diversity
Makes sure all organisms are genetically different

15. Independent Assortment
The random distribution of homologous chromosomes during Meiosis

16. Crossing-Over
DNA exchanged between homologous chromosomes during Prophase I

17. Random Fertilization
Random sperm cell fuses with a random egg cell

18. http://biog-101-104. bio. cornell

19. Oogenesis Process that creates female egg cells
Of the four haploid cells created during Meiosis, three will die as polar bodies and one will survive as an egg cell

20. Spermatogenesis Process that creates male sperm cells
All four haploid gamete cells will develop into sperm cells

21. 7-2 Sexual Reproduction Asexual – One parent
Creates offspring that are clones
Sexual Reproduction – two parents
Creates genetically different offspring

22. Advantages for Each
Asexual allows organisms to produce many offspring in a short amount of time
Sexual reproduction creates genetic diversity

23. Disadvantages for Both
Asexual creates very little genetic diversity
Sexually reproducing organisms depend on finding mates (takes time and NRG)

24. Alternation of Generations
Organisms cycle through diploid and haploid life stages
Haploid Life Cycle – haploid cells occupy the major portion of the life cycle (protists, fungi)

25. Diploid Life Cycle - adult individuals are diploid, gametes are the only haploid cells (animals)
Alternation of Generations – plants, algae, and some protists alternate between a haploid and diploid phase
Sporophyte – diploid phase when spores are made

26. Gametophyte - haploid phase where gametes are made