Biology, 6th Edition

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Greg Steinberg Mrs. Wierzbowski AP Biology Chapter 12 The Cell Cycle A. The Key Roles of Cell Division a. Reproduction, growth, and repair. i. When a cell divides, a whole new organism is produced. ii. Division allows multicellular organisms to reproduce too. iii. When an organism is complete, cell division replaces and repairs old cells. iv. A cell duplicates DNA, it does not just split it. b. Legacy of DNA i. The entire genetic code of an organism is called it’s genome. ii. All of the cells DNA must be copied for the daughter cell to gain it. iii. During replication, the DNA is packaged into chromosomes, which are very tight “bundles” of compact DNA. iv. Somatic cells of a human has 46, gamete cells have half as many, or 23. v. Each DNA is thousands of genes (Humans are said to have 20000- 25000 genes). vi. Proteins maintain the structure of DNA, as well as organize it. vii. The chromatin condenses before replicating, making the chromosomes visible with even just a light microscope. viii. Two chromatids make up a chromosome. They are bound towards the middle of each other, forming a centromere. c. Mitosis and Meiosis i. Mitosis occurs after the division of the cytoplasm. ii. The male gamete and female gamete meet, to form a somatic cell. Through mitosis and cytokinesis, these cells divide and reproduce, making trillions of cells for a multicellular organism. iii. Meiosis makes daughter cells that have half of an organisms genetic information, allowing gametes to form. B. The Mitotic Cell Cycle a. Mitotic phase and Interphase i. Mitosis is the mitotic phase of the cell cycle, just a small fraction. ii.
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bio12 - Greg Steinberg Mrs Wierzbowski AP Biology Chapter...

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