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CHAPTER 11: INTRODUCTION TO GENETICS Standards B.1.8, B.1.21, B.1.28, B.1.29 Section 11.4: Meiosis
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ASEXUAL REPRODUCTION SEXUAL REPRODUCTION
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SO, Where does the baby get its genetic material? Sexual Reproduction = 2 Parents
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Section 11.4: Meiosis IMPORTANT CONCEPT: Because organisms get half of their chromosomes from mom and half from dad, the chromosomes from each parent MUST be divided in half before they can be passed on.
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Section 11.4: Meiosis Homologous Chromosomes A matching pair of chromosomes that have the same genes. One of these chromosomes comes from MOM. The other chromosome comes from DAD. Every animal has a unique # of chromosomes. Humans have 46 chromosomes. (23 from MOM, 23 from DAD)
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Section 11.4: Meiosis Diploid Cell A cell that contains BOTH sets of chromosomes (mom AND dad). (2 sets = diploid = 2N) All body cells! Haploid Cell A cell that contains ONE set of chromosomes (mom OR dad). (1 set = haploid = 1N) All sex cells!
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Section 11.4: Meiosis Meiosis The process of reduction division in which the number of chromosomes in a cell is cut in half. Homologous chromosomes are separated in the process. mom! dad!
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Section 11.4: Meiosis There are TWO major divisions during meiosis. Meiosis I Reduction Division Homologous chromosomes pair up to form tetrads.
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Section 11.4: Meiosis Meiotic “Crossing Over” Crossing over: The exchange of alleles between homologous pairs while in tetrads. Chromosomes “trade” information! **Increases Diversity**
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Section 11.4: Meiosis There are TWO major divisions during meiosis. Meiosis II This happens the SAME way as Mitosis! During Meiosis II, the sister chromatids are pulled apart. This results in 4 haploid daughter cells.
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Meiosis II This happens the SAME way as Mitosis! During Meiosis II, the sister chromatids are pulled apart, resulting in 4 haploid daughter cells.
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Section 11.4: Meiosis Results in 2 genetically identical diploid cells. Allows organisms to grow and replace parts. Results in 4 genetically different haploid cells. Sex cell (gamete) production. MITOSISMEIOSIS
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