Ch8 Cell Reproduction

Ch8 Cell Reproduction - Danielle Hirsch Biology Notes 9/20...

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Danielle Hirsch Biology Notes 9/20 Chapter 8- Cell Reproduction 1. Intro to Cell Division a. Two come from one i. “Mother” cell (parent cell) gives rise to two “daughter cells” ii. Geometric growth in numbers: 1-2-4-8-16-32… b. Cell division copies: i. Genome (= all DNA of an organism) ii. Cytoplasmic contents c. Why do Cells Divide? i. For growth and development ii. For repair and replacement iii. For reproduction 1. Asexual reproduction: a. Mitosis- makes exact copies of genome 2. Sexual reproduction: a. Meiosis – makes gametes (egg and sperm) with ½ the genome b. Gametes must fuse (fertilization) to form a zygote 2. The Eukaryotic Genome a. Eukaryotic Genome is 2 or more chromosomes [8.3] i. # chromosome not = complexity 1. Ex. Mosquito=6, human =46, adder’s tongue fern=102o b. Each chromosome carries one or two copies of long DNA molecules i. Prokaryotes have 1 short DNA, in a circle c. Chromosome structure is complex [8.5]
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i. DNA wound around histone proteins, making nucleosomes ii. Chromatin=entire fiber of DNA and protein iii. Condensed chromatin forms visible chromosomes 1. Seen only during division d. After DNA replication, chromosomes have two sister chromatids [8.6] i. Each chromatid has only one copy of DNA ii. Chromatids join at centromere 3. The Cell Cycle [8.7]**study—for growth and division a. Interphase 1. Longest part of cycle 2. Chromosomes NOT visible ii. G1 Phase (Gap 1) 1. Only one DNA molecule per chromosome 2. Cytoplasmic contents double 3. “checkpoint” at end of G1 a. Requires chemical signal to proceed to S phase b. Many cells enter a “G0” non-dividing phase iii. S Phase (synthesis) 1. Replication process for DNA iv. G2 Phase (Gap 2) 1. Now two copies of DNA per chromosome
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Ch8 Cell Reproduction - Danielle Hirsch Biology Notes 9/20...

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