Stages

• Meiosis I and Meiosis II represent a double division of the nucleus to produce 4 haploid cells from 1 diploid parent cell (Don’t Forget Cell cycle: Interphase → Prophase → Metaphase → Anaphase → Telophase)
• Interphase I: Similar to mitosis interphase; chromosomes replicate (S phase) and centriole pairs - each duplicated chromosome consists of two identical sister chromatids attached at their centromeres
• Prophase I: The longest and most complex phase (90% of the whole of meiosis)
• Metaphase I: Shortest phase, bivalents align at the metaphase plate/equator, leading to independent assortment (orientation of homologous pairs to poles is random)
• Independent assortment: 2^n = formula - Diploid; in humans 2n = 46 → n = 23 → 2^n = 8,388,608 (over 8 mil), sounds large but most code for something that isn’t visible or noticeable
• Anaphase I: Homologous chromosomes separate and move towards the poles but sister chromatids remain attached at their centromeres
• Telophase I: Each pole now has a haploid set of chromosomes, cytokinesis occurs and two haploid daughter cells are formed
• Cytokinesis I: in animal cells, the division of the cytoplasm produces 2 haploid cells, each containing one of each of the homologous pairs of chromosomes but in most plant cells, it goes from Anaphase I to Prophase II directly
• Meiosis II: No interphase II or very short (no more DNA replication), prophase to telophase II are the same as they are in mitosis
• Cytokinesis II: Cytoplasm division occurs in both cells produced from cytokinesis I, producing 4 haploid gametes, sometimes referred to as tetrad (each has 1 of each homologous chromosome, and all 4 will likely be different)
• Early Prophase I: Chromosomes become more visible as they condense by supercoiling (becoming shorter and thicker); bivalent is two chromosomes or four chromatids (sister and non-sister chromatids)

  A) bivalent

  B) homologous

  
• Late Prophase I: Crossing over; non-sister chromatid sections break and reattach to the other chromatid, occurs at the chiasmata (crossing over sites); average 2-3 cross-over events on each homologous pair