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Understanding Meiosis: The Cell Division for Genetic Diversity

Explore the process of meiosis, producing haploid cells for sexual reproduction, and learn about diploid and haploid cells, homologous chromosomes, and advantages of sexual reproduction.

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Understanding Meiosis: The Cell Division for Genetic Diversity

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  1. Chapter 11 Meiosis and Sexual Reproduction Section 1 Reproduction

  2. Chapter 11 Section 1:Reproduction Key Vocabulary Terms Adapted from Holt Biology 2008

  3. Meiosis A special process of cell division that results in haploid sex cells The total number of chromosomes decreases to half the original number

  4. Gamete A reproductive cell; a haploid reproductive cell that unites with another reproductive cell to form a zygote;

  5. Zygote The cell that results from the fusion of gametes (a fertilized egg)

  6. Diploid Describes a cell, nucleus, or organism that contains two sets of chromosomes diploid cell

  7. Haploid Describes a cell, nucleus, or organism that has only one set of unpaired chromosomes haploid cell

  8. Homologous Chromosomes Chromosomes that have the same order of genes, the same structure, and that pair during meiosis

  9. Chapter 11 Section 1:Reproduction Supplementary Words Adapted from Holt Biology 2008

  10. Chapter 11Section 1: Reproduction Notes Adapted from Holt Biology 2008

  11. Reproduction Asexual Reproduction - A single parent produces genetically identical offspring

  12. Asexual Reproduction Prokaryotes Reproduce by splitting - binary fission

  13. Asexual Reproduction Unicellular Eukaryotes Reproduce by mitosis and cytokinesis

  14. Asexual Reproduction Multicellular Eukaryotes Reproduce by Fragmentation – sea stars Budding – yeast, hydra Cuttings - plants Parthenogenesis – water fleas, some bees

  15. Advantages of Asexual Reproduction Many offspring are produced in a short mount of time. Little energy is required for Gamete production Finding a mate

  16. Sexual Reproduction Two parents produce genetically different offspring

  17. Sexual Reproduction Background Types of cells: Germ cells – cells that produce gametes Somatic cells – other body cells that do not participate in sexual reproduction

  18. Advantages of Sexual Reproduction Genetically diverse populations Variety increases the likelihood that some individuals will survive if the environment changes.

  19. Chromosome Number Each chromosome has thousands of genes.

  20. Chromosome Number Each species has a certain number of chromosomes. Mosquitoes = 6 Chimpanzees = 48 Humans = 46 Potato = 48

  21. Human Chromosome Number • Each somatic cell has two sets of 23 chromosomes. • Each gamete has one set of 23 chromosomes. • When fertilization occurs, the zygote will have two sets of 23 chromosomes – one from each gamete. 23 46 23 + =

  22. Haploid and Diploid Cells • Gametes are haploid • Symbol: n • Somatic cells are diploid • Symbol: 2n • For humans, n = 232n = 46

  23. Homologous Chromosomes • Paired chromosomes found in diploid cells. Chromosome Chromosome Centromere Centromere Genes Genes Chromatids

  24. Autosomes and Sex Chromosomes Autosomes Chromosomes with genes that do not determine sex

  25. Autosomes and Sex Chromosomes Sex chromosomes Chromosomes with genes that determine sex, X and Y in humans Boys have an X and a Y Girls have two Xs

  26. autosomes 1-22 sex chromosomes 23

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