Number of Daughter Cells Produced from Mitosis and Cytokinesis
Mitosis, followed by cytokinesis, results in the formation of two daughter cells that are genetically identical to the parent cell. This process is essential for growth, repair, and asexual reproduction in multicellular organisms.
Detailed Breakdown of the Process
1. Mitosis (Nuclear Division)
Mitosis ensures that the genetic material is evenly distributed between two nuclei before the cell physically divides. It consists of four main phases:
a) Prophase
- The chromatin condenses into visible chromosomes, each consisting of two sister chromatids.
- The nuclear envelope breaks down.
- The spindle fibers begin to form from centrosomes (in animal cells) or microtubules (in plant cells).
b) Metaphase
- Chromosomes align in the center of the cell (the metaphase plate).
- Spindle fibers attach to the centromeres of the chromosomes.
c) Anaphase
- Sister chromatids are pulled apart by the spindle fibers toward opposite poles of the cell.
- Each chromatid now becomes an independent daughter chromosome.
d) Telophase
- The chromosomes de-condense back into chromatin.
- Two new nuclear envelopes form around the separated chromosomes.
- The spindle fibers disassemble.
2. Cytokinesis (Cytoplasmic Division)
After mitosis, the cell must divide its cytoplasm, organelles, and membrane to complete the formation of two daughter cells.
- In Animal Cells: A cleavage furrow forms as a contractile ring made of actin and myosin filaments tightens around the middle of the cell, pinching it into two separate cells.
- In Plant Cells: A cell plate forms from vesicles carrying cell wall materials, gradually expanding until it fuses with the existing cell wall, creating two distinct cells.
Key Characteristics of Daughter Cells:
- They are genetically identical to the original parent cell.
- They each have the same number of chromosomes as the parent cell (diploid in most cases, like in human somatic cells with 46 chromosomes).
Thus, mitosis + cytokinesis = 2 daughter cells that are clones of the original cell.
Final Outcome: Two Genetically Identical Daughter Cells
- Each daughter cell receives a complete set of chromosomes (diploid in most organisms).
- The two daughter cells are exact copies of the original parent cell.
- The cells can now enter interphase and prepare for the next cycle of growth and division.
