Meiosis Review

1. Meiosis I or II? Identify 3 ways you know this….

2. Meiosis I or II? Identify 3 ways you know this….

3. What phase of meiosis is this. How do you know this 3. What phase of meiosis is this? How do you know this? What important event has occurred in this phase?

4. What phase? Anaphase II

5. What phase? What important event is happening here? Prophase I

6. What phase? Anaphase I

7. What phase? Metaphase I

8. What phase? Telophase II

9. What phase? Prophase II

10. What phase? Metaphase II

11. What phase? Telophase I

Crossing Over A physical exchange of equivalent segments of maternal and paternal homologous chromosomes occurs. If there are allelic differences between these segments, then the products of crossing-over are genetic recombinants for those alleles.

Genetic Variation The number of possible chromosome combinations is 2n, where n is the number of chromosome pairs. For example, in fruit flies, which have 4 chromosome pairs, the number of possible combinations is 2n, or 16. For humans, with 23 chromosome pairs, there are over 8 million metaphase arrangements possible…. A diploid cell with 4 chromosomes can produce 4 different combinations of chromosomes in going from diploid to haploid, and crossing over only adds to the variations that can be seen.