Cell division is a fundamental process by which a single cell duplicates its contents and splits into two daughter cells. It's essential for:
Growth and development: Multicellular organisms grow by producing new cells through division. This allows us to go from a single fertilized egg to a complex organism with trillions of cells.
Repair and replacement: Worn-out or damaged cells are constantly being replaced through cell division. This helps maintain tissues and organs.
Reproduction: In unicellular organisms, cell division is the primary means of reproduction.
There are two main types of cell division:
Mitosis
This is the most common type of cell division.
It results in two daughter cells that are genetically identical to the parent cell.
Each daughter cell receives a complete set of chromosomes, the same number as the parent cell.
key stages in mitosis:
Prophase: Chromosomes condense and become visible.
Metaphase: Chromosomes align at the center of the cell.
Anaphase: Sister chromatids separate and move towards opposite poles of the cell.
Telophase: Nuclei form around the separated chromosomes in the two daughter cells.
Cytokinesis: The cytoplasm divides, forming two completely separate daughter cells.
Meiosis:
This type of cell division is crucial for sexual reproduction.
It leads to the formation of four daughter cells, each with half the number of chromosomes as the parent cell (haploid cells).
Meiosis involves two meiotic divisions:
Meiosis I: Similar to mitosis, chromosomes condense and separate, but the number of chromosomes is halved.
Meiosis II: Sister chromatids separate, resulting in four haploid daughter cells.