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Published byOswin Wilcox Modified over 9 years ago
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Why do cells Divide? For Growth Development Repair Reproduction Larger cells: - can miscommunication with DNA - have trouble processing information - struggle to exchange materials across the membrane (SA:V)
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Cell Division Two Types of reproduction Asexual Reproduction ○ Genetically identical offspring from a single parent’s cells dividing Sexual Reproduction ○ Fusion of sex cells from 2 individuals
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Advantages of Reproduction Types Asexual: Survival Strategy for single celled organisms Offspring are genetically identical to parent. Occurs rapidly under favorable conditions. Lower energy input Sexual: Survival Strategy for multi-cellular organisms Offspring are genetically varied from parent An advantage in environments that change frequently Higher energy input
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Cell Division A single cell divides into 2 daughter cells
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The Cell Cycle A Series of steps a cell goes through Growth of the cell / parts Synthesis of new DNA Division of the cell
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Cell Division The Beginning of the Cycle is called Interphase G 1 - intense growth and making of new proteins and organelles S - new DNA is synthesized so 2 copies of the chromosomes exist G 2 – Preparation and replicating organelles
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The Cell Cycle A Series of steps a cell goes through: -growth, preparation, division B. Prokaryotes: - asexual reproduction called binary fission C. Eukaryotes - Four phases: G 1, S, G 2, and M
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The Cell Cycle The Second Stage in the cycle is Mitosis (division of nucleus and cytoplasm)
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III. Chromosomes A. Packages of DNA (genetic information) that is bundled together. centromere chromatids Duplicated chromosome
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Chromosomes (cont.) B. Prokaryotes -Contain single, circular chromosome. Bacterial chromosome plasmids
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Chromosomes (cont) C. Eukaryotes -contain multiple chromosomes -Chromatin -DNA is generally wrapped around proteins called histones.
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Counting Chromosomes Chromosomes can have one or two sets of DNA. Count chromosomes by counting the number of centromeres
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a. Mitosis Prophase – 1. genetic material condenses 2. chromosomes become visible 3. spindle starts to form 4. nuclear envelope disappears
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Mitosis (cont.) Metaphase – 1. Duplicated chromosomes line up in middle 2. Spindle fibers connect to centromeres
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Mitosis (cont) Anaphase – 1. Sister chromatids separate and move to opposite ends of the cell
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Mitosis (cont) Telophase 1. Condensed chromosomes begin to spread out into chromatin. 2. Nuclear envelope re-forms
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b. Cytokinesis -division of the cytoplasm -splits parent cell into identical 2 daughter cells
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Cytokinesis (cont) Animal Cells: membrane pinches inward Plant Cells: cell plate develops from inside
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Cell Division Animation http://highered.mcgraw- hill.com/sites/0072495855/student_view 0/chapter2/animation__how_the_cell_cy cle_works.html http://highered.mcgraw- hill.com/sites/0072495855/student_view 0/chapter2/animation__how_the_cell_cy cle_works.html
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