I am a text-based AI and cannot create diagrams. However, I can describe the stages of meiosis in detail, which you can use to draw your own diagram.
Meiosis I: Reductional Division
- Interphase: Before meiosis begins, the cell undergoes interphase, where DNA is replicated. Each chromosome now consists of two identical sister chromatids.
- Prophase I:
- Chromosomes condense and become visible.
- Homologous chromosomes pair up, forming structures called bivalents or tetrads (each consisting of four chromatids).
- Crossing over occurs: segments of DNA are exchanged between non-sister chromatids of homologous chromosomes. This creates new combinations of alleles.
- The nuclear envelope breaks down, and the spindle fibers begin to form.
- Metaphase I:
- Homologous chromosome pairs (bivalents) align along the metaphase plate (the equator of the cell).
- The orientation of each pair is random (independent assortment).
- Anaphase I:
- Homologous chromosomes separate and are pulled to opposite poles of the cell by the spindle fibers.
- Sister chromatids remain attached at their centromeres.
- Telophase I & Cytokinesis:
- Chromosomes arrive at the poles. Each pole now has a haploid set of chromosomes, but each chromosome still consists of two sister chromatids.
- The cytoplasm divides, forming two haploid daughter cells.
Meiosis II: Equational Division
- Prophase II:
- In each of the two haploid daughter cells, chromosomes condense again.
- The nuclear envelope breaks down (if it reformed in Telophase I), and new spindle fibers form.
- Metaphase II:
- Chromosomes (each still composed of two sister chromatids) align along the metaphase plate in each cell.
- Anaphase II:
- Centromeres divide.
- Sister chromatids separate and are pulled to opposite poles of the cell. They are now considered individual chromosomes.
- Telophase II & Cytokinesis:
- Chromosomes arrive at the poles and begin to decondense.
- Nuclear envelopes reform around the chromosomes.
- The cytoplasm divides in each cell.
The result is four haploid daughter cells, each genetically distinct from the parent cell and from each other.