Meiosis I

• Interphase has 4 chromosomes as chromatins.
• During S phase, it becomes a diploid cell with copies from mom and dad. It has 4 chromosomes and 8 chromatids.
• In Meiosis I, there is Prophase I, Metaphase I, Anaphase I, Telophase I.
• In Prophase I, the cell is a diploid cell. The nuclear membrane dissolves, spindles form, and chromosomes appear.
• Tetrads form during Prophase I and crossing over occurs.
• Tetrads: homologous pairs that pair up.
• Crossover: creates as much genetic variety.
• During crossover, the same type of genetic information has to be swapped.
• Only chromatids next to each other crossover during Prophase I.
• During metaphase I, homologous pairs line up down the middle. Independent assortment occurs.
• Independent assortment: when chromosomes switch sides.
• Equilateral plate is split down the middle of the cell.
• Anaphase I is when homologous pairs are pulled apart towards the end of the cell by spindles.
• During telophase I, chromosomes unravel, the nuclear membrane reforms, the cell pinches in and cytokinesis occurs. These cells are haploid cells.
• In telophase I, there is one copy of big & small mom or dad in each cell which has 2 chromosomes and 4 chromatids in each cell.
• The 1st steps of meiosis are to make haploid cells, but we still have genetic DNA replicates.