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Cell Division

Cell Division. Objectives 1. Describe the cell cycle. 2. Describe the events in each stage of mitosis. 3. Explain cancer as a disease of the cell cycle. Pg 240-252. Think! Think!! Think!!!.

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Cell Division

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  1. Cell Division • Objectives • 1. Describe the cell cycle. • 2. Describe the events in each stage of mitosis. • 3. Explain cancer as a disease of the cell cycle. Pg 240-252

  2. Think! Think!! Think!!! • Does a living thing grow larger because it increases the size of its cells or because it produces more cells?

  3. Think! Think!! Think!!! • Living things grow because they produce more cells. • There is a limit to the size that cells can grow. • The DNA that is in the nucleus of each cell is like the library of a small town. When the town is small, there are enough books for the residents to share. If the town population were to increase, there would be a shortage of books. • So instead of growing larger, cells must reproduce.

  4. Cell Division • Cell Division – the process by which a cell divides into two new identical daughter cells • Before cell division, the DNA of the cell is copied, so each daughter cell gets a copy. • DNA – (deoxyribonucleic acid) the large molecule in the nucleus of each cell that carries genetic information

  5. Chromatin • Chromatin - DNA in the nucleus that looks like spread out “strings” when the cell is not dividing

  6. Chromosomes • Chromosomes – condensed chromatin visible in the nucleus when the cell is dividing • Humans have 46 chromosomes or 23 pairs.

  7. Chromosomes • Before cell division, each chromosome is duplicated. The identical chromosomes attach to each other. • Sister Chromatids – two identical chromosomes attached to each other • Centromere – the place that the sister chromatids are attached to each other

  8. The Cell Cycle • Interphase • G1 – “G for Grow” the cell size increases • S – “S for DNA Synthesis” the chromosomes are duplicated • G2 – centrioles and other organelles required for cell division are made • Mitosis – the duplicated chromosomes separate, has four phases • Cytokinesis – the cell physically splits in two

  9. Cancer: A Disease of the Cell Cycle • Cancer – a disorder in which some of the body’s cells divide uncontrollably. • The cells that continue to divide cause masses called tumors. • Causes can be tobacco, UV radiation, or viruses.

  10. Prophase – chromatin condenses into sister chromatids, centrioles separate, spindle forms, nuclear envelope breaks down Metaphase – sister chromatids line up across middle of cell, each is connected to a spindle fiber at its centromere Anaphase – sister chromatids separate and move to opposite sides of the cell Telophase – sister chromatids lose their shape and become chromatin, two new nuclear envelopes form http://www.rattlerscience.com/life/classes/preapbio/documents/Unit%203/chapter10/cell_cycle.swf http://bio.rutgers.edu/~gb101/lab2_mitosis/graphics/aavideo.mov Mitosis

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