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Cellular Reproduction Mitosis Cell reproduction occurs when parent cells divide. Two new daughter cells arise from each parent cell. The production of new cells serves several functions • Early Development 1. GROWTH: Increase the number of cells 2. SPECIALIZE: Production of the many different cell types that will make up the mature organism • After Full Development 1. Repair damage tissues 2. Replace cells that are lost from the outer surface 3. Resist disease Small cells are better than large cells. There is more surface area for the cell membrane to meet the cell’s needs Cells stop growing or reproduce before they reach the point of: • Starving because of a lack of nutrients • Being poisoned because of waste buildup Mitosis The process by which chromosomes are duplicated and distributed to daughter nuclei Each daughter cell nucleus carries the same set of genetic information as the parent nucleus Interphase and Mitosis make up the cell cycle Mitosis is a series of “phases” where the end of one phase blends with the beginning of the next Interphase (NOT part of mitosis) • The in-between phase where chromosomes replicate • Interphase begins when cell reproduction is completed. • Interphase is a non-reproducing phase in which the cell spends most of its life Early Interphase (still NOT mitosis) • New parts such as ribosomes and mitochondria are produced – Animal cells: new centrioles – Plant cells: new chloroplasts Interphase • Look for a. Complete nuclear membrane b. Chromosomes NOT visible Nuclear membrane chromatin Interphase Prophase • Chromosome become dark and thick • Look for: a. Nuclear membrane disappearing b. Chromosomes look like dark, thick threads Nuclear Membrane Chromosome threads Mitosis - Prophase Prometaphase • Chromosomes move to the equator • Look for: a. Nuclear membrane is gone b. Paired chromosomes attached with centromeres move toward the equator Metaphase • Chromosomes line up and attach to spindle fibers • Look for: chromosomes lined up at the equator Mitosis - Metaphase Anaphase • Chromosomes (chromatids) move to the poles • Look for: chromatids pulling apart at the centromeres Mitosis - Anaphase Telophase • The cell begins to divide and 2 new daughter cells develop. The nuclear membrane starts to reappear. • Look for: a. (animal) cleavage furrow b. (plant) equitorial plate Mitosis – Late Telophase Plant Cell – equatorial plate forming Animal Cell – cleavage furrow forming Cytokinesis • The cytoplasm splits • Two new daughter cells are formed • The resulting cells enter back into Interphase Daughter Cells Mitosis Prophase Telophase Interphase Interphase Telophase Anaphase Prophase Interphase Metaphase Prophase It is estimated that 25 million cell division occur every second in the human body Different types of cells divide at different rates • Red Blood Cell form in bone marrow and reproduce rapidly to keep up with the need for new cells • Muscle and Nerve cells never reproduce once they mature • Human Liver Cells divide only when new cells are needed to repair wounds. If one type of cell grows too rapidly, the normal organization of the organism is disrupted. Cancer is one kind of disruption. When there is a rapid, uncontrolled division of one kind of cell, it invades and disrupts cells in other tissue. Genetic Uniformity = Mitosis The genes in every daughter cell are identical to the genes in the parent cell ******BODY CELLS