1. Meiosis Biology 3 Kawashima Philippine Science High School SY 2009-2010

4. Homologous chromosomes condense at prophase I Homologous chromosomes pair along their lengths, aligned gene by gene Synaptonemal complex forms between homologues, holding them together along their lengths

5. Homologous chromosomes condense at prophase I Synaptonemal complex disassembles in late prophase I, and each chromosome pair become visible as a tetrad A tetrad is a group of four chromotids Each tetrad has one or more chiasmata, cris-crossed regions where crossing-over has occured

6. Tetrads align on the metaphase plate at metaphase I Chiasmata are still intact One chromosome of each pair face the pole Chromatids of homologous chromosomes are attached to kinetochore microtubules from one pole

7. Homologous chromosomes separate at anaphase I Sister chromatids remain attached at the centromere Sister chromatids move towards the same pole Homologous chromosomes, each composed of two sister chromatids, move to opposite poles

8. Each half has a complete haploid set of chromosomes at telophase I Each chromosome is still composed of two sister chromatids Cytokenesis begins to form two daughter cells, each with a haploid set of chromosomes No chromosome doubling occurs between telophase I and prophase II, as they have already been replicated

9. Meiosis I Homologous chromosomes condense at prophase I Tetrads align on the metaphase plate at metaphase I Homologous chromosomes separate at anaphase I Each half has a complete haploid set of chromosomes at telophase I