Cell division is a fundamental process in which a parent cell divides into two or more daughter cells.
It allows for growth, repair, and reproduction in living organisms.
There are two main types of cell division: mitosis (in eukaryotic cells) and binary fission (in prokaryotic cells).
Additionally, eukaryotic organisms undergo a specialized form of cell division called meiosis to produce gametes (sperm and egg cells) for sexual reproduction.
Interphase of cell division
Interphase is the preparation phase, divided into three stages:
G1 Phase (Gap 1): The cell grows, produces proteins, and checks conditions for DNA replication.
S Phase (Synthesis): DNA is replicated, resulting in two identical sets of chromosomes.
G2 Phase (Gap 2): The cell continues to grow, produces proteins needed for mitosis, and checks for DNA errors.
M Phase (Mitotic Phase)
The M phase involves:
Mitosis: Division of the nucleus and chromosomes into two identical nuclei.
Cytokinesis: Division of the cytoplasm, resulting in two separate daughter cells.
This cycle ensures proper cell growth, DNA replication, and division, maintaining healthy cell function.
M Phase (Mitotic Phase)
Cell division is a fundamental process by which a single cell divides into two or more daughter cells.
This process is essential for growth, development, and repair in living organisms.
There are two main types of cell division: mitosis and meiosis.
1. Mitosis:
Mitosis is responsible for the growth and maintenance of tissues.
It's how organisms grow and how they replace old or damaged cells.
Process:
Interphase: The cell prepares for division by replicating its DNA, so each daughter cell will have a complete set of chromosomes.
Prophase: The chromatin condenses into visible chromosomes, and the nuclear membrane begins to disintegrate. Spindle fibers start to form.
Metaphase: The chromosomes align in the middle of the cell, attached to spindle fibers.
Anaphase: The chromosomes are pulled apart, with each half moving to opposite sides of the cell.
Telophase: The chromosomes reach the poles, and a new nuclear membrane forms around each set, creating two nuclei.
Cytokinesis: The cell's cytoplasm divides, forming two separate daughter cells, each with an identical set of chromosomes.
2. Meiosis
Meiosis is crucial for sexual reproduction and occurs in germ cells (sperm and eggs).
It reduces the chromosome number by half, resulting in four genetically diverse daughter cells, each with half the number of chromosomes as the original cell.
Process:
A. Meiosis I:
Prophase I: Chromosomes condense, and homologous chromosomes pair up, exchanging segments in a process called crossing over.
Metaphase I: Paired homologous chromosomes line up at the cell’s equator.
Anaphase I: The homologous chromosomes are pulled apart to opposite sides.
Telophase I and Cytokinesis: The cell divides into two non-identical daughter cells, each with half the original number of chromosomes.
B. Meiosis II:
Prophase II: The two cells prepare for another division.
Metaphase II: Chromosomes line up at the equator of each cell.
Anaphase II: Sister chromatids are pulled apart to opposite poles.
Telophase II and Cytokinesis: Both cells divide, resulting in four non-identical daughter cells, each with half the original chromosome number.
Key Differences Between Mitosis and Meiosis
Mitosis: Produces two genetically identical daughter cells with the same number of chromosomes as the parent cell.
Meiosis: Produces four genetically diverse daughter cells with half the chromosome number of the parent cell.