VIEWS: 14 PAGES: 34 POSTED ON: 7/27/2012
The Cell Cycle Molecular Biology Sumner HS Cell Reproduction/Division The ability of organisms to reproduce their kind is the one characteristic that best distinguishes living things from nonliving. The continuity of life is based on the reproduction of cells, or cell division. Cell Division Importance Multicellular organisms depend on cell division for Development from a fertilized cell Growth Repair or replacement of “bad” cells Big Growth We start as one cell We end up being made of trillions of cells They don’t magically appear **Poof!** The result of countless cycles of growth and division of cells. Question to ponder... What tasks does a cell need to do in order to divide? Have a 2nd copy of DNA Have enough cytoplasm and organelles for a second cell The Cell Cycle Cells go through predictable, controlled patterns of growth or development and division. Called the cell cycle The Cell Cycle Big Picture Cell 1 Interpha Cell 1 se/ Mitosis Cell 2 Big Picture Cont’d1 Cell Interpha se/ Mitosis Cell 1 Cell 3 Cell 2 Cell 2 Interpha se/ Mitosis Cell 4 Cell Cycle Major Phases Interphase = period of growth, DNA replication and protein synthesis Mitosis = cell division Interphase Interphase can be divided into subphases G1 phase S phase G2 phase G1 Phase Rapid growth High metabolic activity Making lots of proteins S Phase DNA is copied (replicated) Cell has twice the number of normal chromosomes. Cell keeps growing G2 Phase More proteins made Mitochondria & other organelles replicate Cell keeps growing Summarize In your own words, summarize each of the phases of interphase. Mitotic Phase The Mitotic Phase has two major phases Mitosis has four sub-phases Prophase Metaphase Anaphase Telophase Cytokinesis New Note Instructions For each of the phases of cell division... ....don’t write down the details I put up Instead, prepare to summarize the main events in about 10 words. Prophase Chromosomes coil up and become visible (twisted rubber band) Centriole begins to form spindle, made from same material as cytoskeleton. Nuclear envelope and nucleolus begin to disappear Summarize! Metaphase Chromosomes move to “equator” of the cell Each half of the chromosome is attached to a spindle fiber at the centromere. Centromere is a protein that joins the two “sister” chromatids, or replicated chromosome pairs Summarize! Anaphase Sister chromatids are pulled apart to opposite ends of the cell. Each chromatid is now a separate chromosome. Summarize! Telophase Genetically identical daughter nuclei form at opposite ends of the cell Nuclear envelope begins to reappear. Summarize! Cytokinesis In animal cells, cytokinesis occurs by a process known as cleavage, forming a cleavage furrow. A “string” of cytoskeleton pinches the cell in two Summarize! Cytokinesis cont. In plant cells, a cell plate forms between the cells after telophase. Mitosis results in two identical cells called daughter cells Real Pictures: Early Prophase Real Pictures: Late Prophase Real Pictures: Metaphase Real Pictures: Anaphase Real Pictures: Early Telophase Real Pictures: Late Telophase Test Yourself Check Your Knowledge prophase, metaphase, anaphase and Identify telophase in these cells.
Pages to are hidden for
"The Cell Cycle"Please download to view full document