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Published byMaria Elinor Webster Modified over 9 years ago
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Reproduction of Cells Asexual Vs Sexual Reproduction
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Asexual Reproduction Single parent passes complete copy of genetic information to its offspring – Identical to parent 4 types – Binary fission – Fragmentation – Budding – Parthenogenesis
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Binary Fission DNA duplicates -> Cell grows -> Cell splits
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Fragmentation Body breaks into several pieces and grow new parts or whole organism
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Budding New individuals split off from existing ones
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Parthenogensis Female makes viable egg that grows into an adult without being fertilized by male
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Sexual Reproduction Genetic material given to offspring by two individuals – Offspring are genetically different from parents – Gametes Reproductive cell (sperm or egg) – Division of germ cell – Haploid cells created through meiosis Union produces zygote
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Meiosis Cell reduces chromosome number in new cells to half the number of the original cell Sperm and egg (1n each, haploid) – Combine result in zygote (2n, diploid)
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Meiosis Interphase Begins with duplicate set of chromosomes like mitosis Two divisions results in four (1n, haploid) cells – Meiosis I and Meiosis II
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Meiosis I Prophase – Chromosomes condense – Spindle fibers form – Homologous chromosomes line up next to each other (synapsis) – Tetrads align side by side Twist around each other Portion breaks off to the adjacent chromatid – Crossing – over results in new mix of genetic information
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Meiosis I Similar to mitosis – Metaphase I – Anaphase I Independent assortment – Telophase I Results in two cells with a chromosome from each pair of homologous chromosomes
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Meiosis II Prophase II, no duplication of chromosomes Metaphase II Anaphase II – Chromatids separate Telophase II Cytokinesis II – 4 new genetically different haploid cells
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Genetic Variation Crossing – over Independent assortment Random fertilization
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Development of Gametes Testes in males – Spermatogenesis to create sperm Ovaries in females – Oogenesis to create ova – 1 egg and 3 polar bodies
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Karyote
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