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Mitosis and Meiosis Biology, where multiplication is the same as division
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Cell Replication All new cells come from existing cells Cells must divide to allow us to grow, repair damaged tissues and reproduce
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Chromosomes Segments of DNA containing many thousand genes Most mammals have 2 sets of chromosomes that code for the same set of characters Aka are diploid
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Haploid vs. Diploid Haploid 1 set of chromosomes (n) Sperm/egg Also male bees, stages of plant and fungal life cycle Diploid 2 set of chromosomes (2n) Somatic (non- gametic) mammal cells Stages of plant/fungi life cycle, female bees
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Homologous Chromosomes Contain different versions of the same gene (aka alleles ) One inherited from mother, one inherited from father
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Chromosome Terminology
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Types of Cell Division Mitosis Creates identical cells Growth, repair, asexual reproduction Meiosis Creates haploid cells with half the chromosomes Creates gametes (sex cells)
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Interphase DNA is replicated before both mitosis and meiosis in interphase Cell also grows bigger and makes proteins necessary for new cells
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Cytokinesis Splitting of cell Occurs after nucleus division (mitosis/meio sis)
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Overview Mitosis One cell division 2 daughter cells Each contains a single copy of all the chromosomes Meiosis Two cell divisions 4 daughter cells Each contain a single copy of half the chromosomes (no homologous chromosomes)
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Mitosis
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Meiosis
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Meiosis I – homologous chromosomes separated
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Meiosis II – Replicated Chromosomes Separate
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Why does it look like some of the chromosomes have been switched? They have! During meiosis, some of the homologous chromosomes are exchanged Increases genetic diversity
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Checkpoints At certain points the cell cycle is halted until a “go signal” is sent Aka CDKs Ensures proper timing of stages, prevents errors and cancers
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The Importance of All This Mitosis creates new identical cells – so every cell in your body is the same Meiosis creates incredibly unique gametes, increasing genetic diversity More diversity = more chances of someone surviving
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You Are A Unique Snowflake You randomly get 1 of every one of the 23 chromosomes from your father and from your mother So there were 2 23 possible combos of sperm and 2 23 possible eggs So about 8,388,608 possible sperms could have led to you So there were about 70,368,470,000,000 possible combinations you could have been (not even counting crossing over!) You really are one in a trillion!
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Your Task In a method of your choosing animate out both mitosis and meiosis You are not responsible for knowing the stage names, but you do need to know the processes So make a flipbook, gif, video etc. demonstrating the continuous process of the cell cycles
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