SCIENCE Lesson 4

• Mitosis is a type of cell division in which the nucleus of the cell divides into two nuclei with identical genetic material.
• Diploid cells (2n) are cells that has two complete sets of chromosomes.
• Haploid cells (n) are cells that contains a single set of chromosomes.
• Mitosis occurs only in somatic cells.
• Mitosis is used for growth and development.
• Mitosis can occur during asexual reproduction and can repair tissues
• STAGES OF MITOSIS : Prophase, Metaphase, Anaphase, Telophase, and Cytokinesis
• Prophase - Chromatin fibers will condense to form chromosomes.
• Prophase - The nuclear membrane dissolves and the spindle fibers are formed.
• Metaphase - Chromosomes move and align themselves at the center of the cell.
• Metaphase - Spindle fibers connect each chromosomes in the kinetochore on its centromere to the centrioles located at opposite poles.
• Anaphase - The proteins that bind the two sister chromatids of each chromosome divide.
• Anaphase - Followed by the movement of the separated chromosomes toward the opposite poles due to the shortening of the spindle fibers
• Telophase - The separated chromosomes (chromatids) are located on the opposite poles.
• Telophase - The spindle fibers dissolve and disappear.
• Telophase - each chromosome in the resulting daughter cell is composed of only one chromatid.
• Cytokinesis - After the division of the nucleus (karyokinesis), the cytoplasm starts to divide (cytokinesis).
• Cleavage furrow - formation happens when cells without cell wall (animal) starts at the exterior of the cell and moves inward until the cell is divided into two cells
• G1 checkpoint: ensures that the cell is ready to undergo DNA synthesis or S phase.
• G2 checkpoint: make sure that the cell is mature enough to divide or undergo M phase
• M checkpoint: occurs during metaphase stage of cell division, sees to it that the cell is ready to complete cell division.
• Controlling Cell Division

  
• Interphase is composed of G1, S, and G2 phases