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Chromosomes vs. Chromatin

Chromosomes vs. Chromatin. Chromosomes Tightly packaged DNA Found only during cell division DNA is not being used for macromolecule synthesis. Chromatin Unwound DNA Found throughout Interphase DNA is being used for macromolecule synthesis. Gene Representations. Gene Representations.

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Chromosomes vs. Chromatin

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  1. Chromosomes vs. Chromatin • Chromosomes • Tightly packaged DNA • Found only during cell division • DNA is not being used for macromolecule synthesis • Chromatin • Unwound DNA • Found throughout Interphase • DNA is being used for macromolecule synthesis

  2. Gene Representations

  3. Gene Representations

  4. Loci (sing. Locus) & Alleles

  5. Homologous Chromosome Pairs • Eucaryote chromosomes come in pairs (homologues) • Normal humans have 46 chromosomes in 23 pairs • One chromosome of each pair comes from an individual’s mother, the other comes from their father • Homologous Chromosomes (chromosome pairs) carry genes that control the same Characters, e.g., eye color, blood type, flower color, height, etc. • Homologous chromosomes have nearly identical structure, banding patterns, and nucleotide sequences • Locus: Physical site on chromosomes where given gene is located • Allele: Different forms of the same gene, e.g., A, B, or O blood-type alleles

  6. Autosomes & Sex Chromosomes Autosomes:Found in both males and females • In humans there are 22 pairs of autosomes • Autosomes that are the same size (& structure) are called homologues Sex Chromosomes:Determine an individual’s gender • One pair of chromosomes (X and Y) • The X and Y chromosomes are not homologous • The X chromosome is much larger than the Y chromosome and contains many genes • The Y chromosome has only a small number of genes • In humans and other mammals females are XX and males are XY

  7. Human Karyotype

  8. Asexual Reproduction

  9. Sexual Cycle (Animals) gamete production a.k.a., syngamy development& repair of soma sequestration of germ line

  10. Variation in Sexual Cycles

  11. Variation in Sexual Cycles Note  Replicating Haploid! note  Alternation of Generations!

  12. Fertilization & Meiosis

  13. Meiosis Overview

  14. synapsis Meiosis I

  15. Meiosis II

  16. Mitosis vs. Meiosis

  17. Variation via the Sexual Cycle 1. Crossing Over: After crossing over and synapsis, sister chromatids are no longer identical. 2. Independent Assortment: Each human can produce over 8.3 million different gametes by random shuffling of chromosomes in meiosis I 3. Fertilization: A couple can produce over 64 trillion (8.3 million x 8.3 million) different zygotes during fertilization. This figure does not take into account diversity created by crossing over

  18. Independent Assortment

  19. Crossing Over (Recombination)

  20. Sordaria (from lab)

  21. Sexual Cycle (Animals) gamete production   a.k.a., syngamy development& repair of soma sequestration of germ line

  22. Probability Theory (ch. 14 preview) • Statistical Independence • Range of Probabilities (0..1) • Law of Multiplication • Calculation for Events not Happening • The Law of Addition

  23. Link to Next Presentation

  24. Acknowledgements http://207.233.44.253/wms/reynolmj/lifesciences/lecturenote/bio3/Chap08.ppt http://people.uncw.edu/pottsl/Bio%20110/Figures/UnitVIII.ppt http://www.bbchs.k12.il.us/Teacher_Pages/Hammond/Powerpoint/Chapter_13.ppt

  25. Synaptonemal Complex

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