Identifying the Stages of Meiosis
- Cells undergoing meiosis can be observed and photographed using specialised microscopes
- The different stages of meiosis have distinctive characteristics meaning they can be identified from photomicrographs or diagrams
Meiosis I or Meiosis II
- Homologous chromosomes pair up side by side in meiosis I only
- This means if there are pairs of chromosomes in a diagram or photomicrograph meiosis I must be occurring
- The number of cells forming can help distinguish between meiosis I and II
- If there are two new cells forming it is meiosis I but if there are four new cells forming it is meiosis II
The distinguishing features at each stage of Meiosis I
- Prophase I: Homologous pairs of chromosomes are visible
- Metaphase I: Homologous pairs are lined up side by side along the equator of spindle
- Anaphase I: Whole chromosomes are being pulled to opposite poles with centromeres intact
- Telophase I: There are 2 groups of condensed chromosomes around which nuclei membranes are forming
- Cytokinesis: Cytoplasm is dividing and cell membrane is pinching inwards to form two cells
The distinguishing features at each stage of Meiosis II
- Prophase II: Single whole chromosomes are visible
- Metaphase II: Single whole chromosomes are lined up along the equator of the spindle in single file (at 90 degree angle to the old spindle)
- Anaphase II: Centromeres divide and chromatids are being pulled to opposite poles
- Telophase II: Nuclei are forming around the 4 groups of condensed chromosomes
- Cytokinesis: Cytoplasm is dividing and four haploid cells are forming
Identifying the stages of meiosis table
Prophase I, Metaphase I , Anaphase I and Telophase I as seen in photomicrographs
Prophase II, Metaphase II , Anaphase II and Telophase II as seen in photomicrographs
Exam Tip
For metaphase remember M for the middle of the spindle and cell which is where the chromosomes will be lined up.For anaphase remember A for away from the middle to the poles, which is where the chromosomes / chromatids are being pulled.