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Cell Division and Mitosis Why is cell division important? Growth Replacement Reproduction Chromosomes Structure in the nucleus that contains hereditary information. Cell Cycle Length of time from formation of a cell to the division of the cell. 2 parts: – Interphase – Mitosis Interphase The cell: – Grows – Develops structures – Copies hereditary info Each chromosome duplicates and forms a chromotid (pair of identical chromosomes attached at the center by a centromere). Mitosis Nucleus divides into two identical nuclei. Divided into: – – – – Prophase Metaphase Anaphase Telophase Prophase Pairs of chromatids are visible. The nucleolus disintegrates. The nuclear membrane disintegrates. In animals, two small structures, called centrioles move to opposite sides of the cell. Spindle fibers begin to stretch across the cell. Prophase Metaphase Pairs of chromatids line up across the center of the cell. The centromere of each pair becomes attached to a spindle fiber from each side of the cell. Metaphase Anaphase Each centromere divides. Spindle fibers shorten. Each half of the chromatid moves to opposite sides of the cell. Anaphase Telophase Spindle fibers disappear. Chromosomes uncoil. New nuclei form. Telophase Division of the Cytoplasm Animal cell: – Membrane pinches in the middle. Plant cell: – A cell plate is laid down across the center of the cell. – New membranes form on each side of the cell plate. Cytokinesis Reproduction Process by which an organism produces others of its same kind. 2 types: – Sexual – Asexual Asexual Reproduction A new organism is reproduced from one organism. The new organism is genetically identical to the parent. Examples: – Potatoes – Strawberries Fission Because bacteria do not have nuclei they cannot reproduce through mitosis. During fission, the bacteria copies its genetic information and than divides in two. Budding The adult grows a bud. The bud eventually falls off and becomes an organism. Ex: hydra Regeneration Ability to regrow body parts. If cut in “half” each part will grow into a new organism. Ex: sponges, planaria, sea stars