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Unit 8: Cell Cycle & Mitosis • Cells make more cells by growing and dividing millions of times a day!! Two types of cell reproduction: • Asexual • Sexual Two types of cell division: • Mitosis • Meiosis Asexual: • One parent • Offspring are clones!! Sexual: • Two parents • Offspring resemble both parents! 1. 2. 3. Body Cells Before a cell can divide it needs instructions!!! • CELL DIVISION OCCURS IN A SERIES OF STAGES, OR PHASES: Mitosis • • • • • • Cell grows!!! • Copies genetic material (DNA) and other cell organelles • 1st Growth Stage • Cells make cytoplasm and organelles • Cells perform normal duties • Cells grow RAPIDLY • Most remain here most of their life. • DNA is copied or replicated. • At the end: each chromosome consists of 2 chromatids attached at the centromere. • 2nd Growth Stage • Cell division structures are made • – • Organelles & proteins are synthesized • PREP for nucleus to divide • Genetic material condenses (shrinks!) to form chromosomes • Nuclear membrane dissolves • Centrioles move to opposite poles • Spindle fibers form • Chromosomes line up in the middle of cell • Spindle fibers are attached!! • Chromosomes are pulled apart and chromatids move to opposite ends of the cell by the spindle fibers. • Chromatids relax • Nuclear membranes form around chromatids • Spindle fibers fall apart • “Division of Cytoplasm” • forms in animal cells – pinching inwards by tiny filaments. • forms in plants cells – forms inbetween the two nuclei • Two daughter cells that are identical to the original cell. Video Clip