Meiosis consists of two main stages:
1. Meiosis I:
* Prophase I: Chromosomes condense and pair up with their homologous counterparts. This is where crossing over (exchange of genetic material between homologous chromosomes) occurs, leading to genetic diversity.
* Metaphase I: Homologous chromosome pairs line up at the center of the cell.
* Anaphase I: Homologous chromosomes are pulled apart, moving towards opposite poles of the cell.
* Telophase I: The cell divides, forming two daughter cells, each with half the number of chromosomes as the original cell.
2. Meiosis II:
* Prophase II: Chromosomes condense again.
* Metaphase II: Sister chromatids (identical copies of a chromosome) line up at the center of the cell.
* Anaphase II: Sister chromatids are pulled apart and move to opposite poles.
* Telophase II: The cell divides, forming four haploid daughter cells, each with half the number of chromosomes as the original diploid cell.
Key Points:
* Diploid (2n): Cells with two sets of chromosomes (one from each parent).
* Haploid (n): Cells with one set of chromosomes.
* Crossing over: The exchange of genetic material between homologous chromosomes, increasing genetic variation.
* Gametes: Haploid sex cells (sperm and egg) produced by meiosis.
Overall, meiosis is a crucial process for sexual reproduction because it ensures that offspring inherit a unique combination of genes from both parents. This genetic diversity is essential for adaptation and evolution.
