Chapter 12 - The Cell Cycle

Chapter 12 - The Cell Cycle - Chapter 12 Class Notes The...

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Chapter 12 Class Notes – The Cell Cycle – Page 1 Max Sauberman AP Biology – Mr. Schilp Chapter 12 The Cell Cycle The Key Roles of Cell Division: The ability of organisms to reproduce best distinguishes living things from nonliving matter. The continuity of life is based upon the reproduction of cells… cell division. Cell Division in Unicellular vs. Multicellular Organisms: In unicellular organisms, the division of one cell reproduces the entire organism. Multicellular organisms depend on cell division for development from a fertilized cell, growth, and maintenance. For example, dead cells are filtered and broken down into raw materials through cell division. Genetic Material and Cell Division: Cell division results in genetically identical daughter cells. Cells duplicate their genetic material before they divide, ensuring that each daughter cell receives an exact copy of the genetic material, DNA. A dividing cell duplicates its DNA, allocates the two copies to opposite ends of the cell, and only then splits into daughter cells. Cellular Organization of the Genetic Material: A cell’s endowment of DNA is called its genome. DNA molecules in a cell are packaged into chromosomes. Eukaryotic chromosomes consist of chromatin, a liquid complex of DNA and protein that condenses to solid chromosome during cell division. Somatic Cells vs. Gametes: Every eukaryotic species has a characteristic number of chromosomes in each cell nucleus. Somatic (nonreproductive) cells have two sets of chromosomes. Gametes (reproduction cells of sperm or egg) have half as many chromosomes as somatic cells. The diploid number is always even, 46, and the haploid number is ½ the diploid number; 23. Thus, somatic cells are diploid cells and gametes are haploid cells.
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Chapter 12 Class Notes – The Cell Cycle – Page 2 There are eight chromosomes in a drosophila, a fruit fly. Distribution of Chromosomes during Cell Division: In preparation for cell division, DNA is replicated and the chromosomes condense. Each duplicated chromosome has two sister chromatids, which separate during cell division. Sister chromatids are only considered when connected; when separate, they are just considered chromosomes. The centromere is the narrow waist of the duplicated chromosome, where the two chromatids are most closely attached. Stages of Eukaryotic Cell Division:
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This note was uploaded on 03/17/2011 for the course BIO 101 taught by Professor Sullivan during the Spring '08 term at Harvard.

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Chapter 12 - The Cell Cycle - Chapter 12 Class Notes The...

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