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CELL DIVISION IS PART OF THE CELL CYCLE. A CYCLE IS ANY ACTIVITY THAT REGULARLY REPEATS. CELL CYCLE INCLUDES INTERPHASE & CELL DIVISION (MITOSIS & CYTOKINESIS) All living things live, grow, reproduce & die in a life cycle. Cell Cycle = normal sequence of development & division of a cell.
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CELL DIVISION IS PART OF THE CELL CYCLE • A CYCLE IS ANY ACTIVITY THAT REGULARLY REPEATS. • CELL CYCLE INCLUDES INTERPHASE & CELL DIVISION (MITOSIS & CYTOKINESIS) • All living things live, grow, reproduce & die in a life cycle. Cell Cycle = normal sequence of development & division of a cell. • 2 main phases, INTERPHASE (cell carries out its functions) & CELL DIVISION (mitosis & cytokinesis) • All cells divide, but only eukaryotes (with nucleus) use mitosis. Each phase in cycle takes certain amount of time from hours to days or years, depending on cell type. • CELL DIVISION MAKES 2 GENETICALLY IDENTICAL CELLS
Cell cycle has 2 parts (interphase & cell division) INTERPHASE: cell is not dividing, but much of cell’s activity occurs here. Cell grows to 2X original size & does its normal life activities. DNA gets copied here to prepare for cell division Mitosis is part of cell division where nucleus divides (not occur in prokaryotes- only 1 chromosome & no nucleus) CYTOKINESIS: division of the parent cell’s cytoplasm (right after mitosis) 2 identical “daughter” cells form with complete set of DNA from parent cell. INTERPHASE & CELL DIVISION
CELL DIVISION MAKES 2 IDENTICAL CELLS • Daughter cells are genetically identical to each other & parent cell (which no longer exists) Will perform same functions. • Mitosis has 4 phases: prophase, metaphase anaphase & telophase • PROPHASE: nuclear membrane disappears, chromatin coils to chromosomes • METAPHASE: chromosomes line up in middle of cell (chromatids attached by centromere) • ANAPHASE: chromatids pull apart to opposite ends of the cell • TELOPHASE: nuclear membrane reappears, chromatids uncoil into chromatin again
DIVISION OF CYTOPLASM • CYTOKINESIS: division of the parent cell’s cytoplasm, occurs right after telophase. • In animal cells, a fiber ring forms in the center of the cell, contracts, and pulls cell membrane inward to pinch parent cell into 2 daughter cells. • In plant cells, a cell plate grows between the 2 new nuclei. It develops into a membrane & eventually becomes part of the cell wall of the 2 daughter cells. • Each DAUGHTER CELL has HALF the cytoplasm of the PARENT CELL. They soon start to grow, eventually becoming the same size as parent cell, and the process continues.