Cell division mitosis and meiosis study.pptx
- 1. CELL DIVISION • MITOSIS • MEIOSIS
- 2. Cell division is a fundamental biological process through which a single cell divides to form two or more daughter cells. It is essential for growth, repair, reproduction, and the maintenance of organisms.There are two main types of cell division: mitosis and meiosis.
- 3. PHASES OF MITOSIS Mitosis is the type of cell division that produces two identical daughter cells from a single parent cell. It is responsible for growth, tissue repair, and asexual reproduction in many organisms. Mitosis occurs in somatic (body) cells and results in two cells that have the same number and type of chromosomes as the original cell.The phases of mitosis ensure accurate DNA replication and distribution to each daughter cell.
- 4. 1, INTERPHASE -The longest stage of a Cell’s life -The time spent between divisions -Produces all materials required for growth -Preparation for cell division II, PROPHASE (The Cell begins the division process) - The nucleolus disappears, - The nuclear membrane breaks apart - The chromosomes becomes visible - The spindle apparatus forms and attaches to the centromeres of the chromosomes III. METAPHASE (The Second phase of mitosis) - The nuclear membrane is gone - The duplicated chromosomes line up along the cell’s equator IV.ANAPHASE (TheThird phase of mitosis) -Diploid sets of daughter chromosomes separate They are pushed and pull toward opposite poles of the cell the spindle fibers IV.TELOPHASE - The nuclear membrane and nucleoli reforms - Cytokinesis is nearly complete - The Cell Plate begins to form - The Cell prepares for final division V. CYTOKINESIS (The Final stage of Mitosis) -The cytoplasm, organelles and nuclear materials are evenly split and two new cells are form -The two new cells each exactly like the other are called- DAUGHTER Cells
- 5. MEIOSIS is a type of cell division that reduces the chromosome number by half, creating four genetically unique daughter cells, each with half the number of chromosomes as the parent cell. It consists of two main stages, Meiosis I and Meiosis II, each with its own sub-stages. Meiosis I This is the reductional division where homologous chromosomes are separated. 1.Prophase I: 1. Chromosomes condense and become visible. 2. Homologous chromosomes pair up in a process called synapsis, forming structures called tetrads. 3. Crossing over occurs, where homologous chromosomes exchange genetic material, increasing genetic diversity. 4. The nuclear membrane begins to break down, and spindle fibers start to form. 2.Metaphase I: 1. Tetrads (pairs of homologous chromosomes) align along the metaphase plate in the center of the cell. 2. Spindle fibers attach to the centromeres of each homologous chromosome. 3.Anaphase I: 1. Homologous chromosomes are pulled apart to opposite poles of the cell by the spindle fibers. 2. Sister chromatids remain attached at their centromeres. 4.Telophase I and Cytokinesis: 1. Chromosomes reach the poles, and the nuclear membrane may briefly reform around each set. 2. The cell divides into two haploid cells, each with half the number of chromosomes (23 in humans).
- 6. 1.Prophase II: 1. Chromosomes condense again if they had relaxed. 2. A new spindle apparatus forms in each of the two cells from Meiosis I. 2.Metaphase II: 1. Chromosomes line up along the metaphase plate in each cell. 2. Spindle fibers attach to the centromeres of each chromosome. 3.Anaphase II: 1. Sister chromatids are pulled apart to opposite poles by the spindle fibers. 2. Each chromatid is now considered an individual chromosome. 4.Telophase II and Cytokinesis: 1. Chromosomes arrive at opposite poles, and nuclear membranes reform around each set of chromosomes. 2. Cytokinesis occurs, resulting in four genetically unique haploid daughter cells, each with a single set of chromosomes (23 in humans). Meiosis II This is the equational division, similar to mitosis, where sister chromatids are separated. These phases are essential for sexual reproduction and contribute to genetic diversity through mechanisms like crossing over and independent assortment.