The cell division shown in Diagram 4.3(a) is called mitosis, while the cell division shown in Diagram 4.3(b) is called meiosis. Here are the differences between the two:
1. Purpose:
- Mitosis: Mitosis is the process by which a single cell divides into two identical daughter cells. It is responsible for growth, repair, and asexual reproduction in multicellular organisms.
- Meiosis: Meiosis is a specialized form of cell division that produces cells with half the number of chromosomes as the parent cell. It is involved in the formation of gametes (sex cells) for sexual reproduction.
2. Number of divisions:
- Mitosis: Mitosis involves a single division, resulting in the formation of two daughter cells.
- Meiosis: Meiosis involves two divisions, resulting in the formation of four daughter cells.
3. Chromosome number:
- Mitosis: The daughter cells produced by mitosis have the same number of chromosomes as the parent cell.
- Meiosis: The daughter cells produced by meiosis have half the number of chromosomes as the parent cell.
4. Genetic variation:
- Mitosis: Mitosis does not contribute to genetic variation as the daughter cells are genetically identical to the parent cell.
- Meiosis: Meiosis generates genetic variation through processes such as crossing over and independent assortment. This leads to the production of genetically diverse daughter cells.
5. Occurrence:
- Mitosis: Mitosis occurs in somatic cells (body cells) throughout an organism's life.
- Meiosis: Meiosis occurs in cells specifically designated for sexual reproduction, such as the cells in the reproductive organs (ovaries and testes).
Overall, mitosis is a process of cell division for growth and repair, while meiosis is a process of cell division for sexual reproduction, resulting in the production of gametes with genetic variation.