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Bio. Ch. 10

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Bio. Ch. 10

  1. 1. Chapter 10: Sexual Reproduction and Genetics 10.1 - Meiosis
  2. 2. Chromosomes and Chromosome Number <ul><li>Trait – Characteristics (hair color, height, or eye color) </li></ul><ul><li>Genes – DNA segment that control the production of a protein. </li></ul>
  3. 3. Homologous chromosomes
  4. 4. Homologous Chromosomes <ul><li>Humans have 46 chromosomes. </li></ul><ul><li>Each parent contributes 23 chromosomes, resulting in 23 pairs of chromosomes. </li></ul><ul><li>Homologous Chromosomes – Chromosomes that make up a pair. One chromosome from each parent. </li></ul>
  5. 5. Haploid and Diploid Cells <ul><li>Haploid Cell – A cell with n number of chromosomes. </li></ul><ul><li>Fertilization – The process by which one haploid gamete combines with another haploid gamete. </li></ul><ul><li>Diploid Cell – A cell with 2n number of chromosomes. </li></ul>
  6. 6. Meiosis I
  7. 7. Meiosis I <ul><li>Meiosis – A type of cell division that reduces the number of chromosomes. (reduction division) </li></ul>
  8. 8. Meiosis I <ul><li>Interphase : </li></ul><ul><li>Chromosomes replicate </li></ul><ul><li>Chromatin condenses </li></ul>
  9. 9. Meiosis I <ul><li>Prophase I : </li></ul><ul><li>Pairing of homologous chromosomes occurs, each chromosome consists of two chromatids. </li></ul><ul><li>Crossing over produces exchange of genetic information. The nuclear envelope breaks down. (Figure 10.4) </li></ul><ul><li>Spindles form. </li></ul>
  10. 10. Prophase I
  11. 11. Meiosis I <ul><li>Metaphase I : </li></ul><ul><li>Chromsome centromeres attach to spindle fibers. </li></ul><ul><li>Homologous chromosomes line up at the equator. </li></ul>
  12. 12. Metaphase I
  13. 13. Meiosis I <ul><li>Anaphase I : </li></ul><ul><li>Homologous chromosomes separate and move to opposite poles of the cell. </li></ul>
  14. 14. Anaphase I
  15. 15. Meiosis I <ul><li>Telophase I : </li></ul><ul><li>The spindles break down. </li></ul><ul><li>Chromosomes uncoil and form two nuclei. </li></ul><ul><li>The cell divides. </li></ul>
  16. 16. Telophase I
  17. 17. Meiosis II <ul><li>Meiosis in only halfway completed at the end of meiosis I. </li></ul>
  18. 18. Prophase II <ul><li>Chromosomes condense. </li></ul><ul><li>Spindles from in each new cell. </li></ul><ul><li>Spindle fibers attach to chromosomes. </li></ul>
  19. 19. Metaphase II <ul><li>Centromeres of chromosomes line up randomly at the equator of each cell. </li></ul>
  20. 20. Anaphase II <ul><li>Centromeres split. </li></ul><ul><li>Sister chromatids separate and move to opposite poles. </li></ul>
  21. 21. Telophase II <ul><li>Four nuclei form around chromosomes. </li></ul><ul><li>Spindles break down. </li></ul><ul><li>Cells divide. </li></ul>
  22. 22. Product! <ul><li>Four cells have formed. </li></ul><ul><li>Each nucleus contains a haploid number of chromosomes. </li></ul>
  23. 23. 10.2 Mendelian Genetics <ul><li>Genetics – The science of heredity. </li></ul><ul><li>Mendel – Father of genetics </li></ul>
  24. 24. The Inheritance of Traits <ul><li>Cross green-seed plant with a yellow-seed plant – Parent (P) generation </li></ul><ul><li>F 1 and F 2 generations </li></ul><ul><li>First Filial (F 1 ) generation – All yellow </li></ul><ul><li>Self fertilization </li></ul><ul><li>Second Filial (F 2 ) generation – 6022 yellow and 2001 green (a 3:1 ratio) </li></ul>
  25. 25. Genes in Pairs <ul><li>Allele – Alternative form of a single gene passed from generation to generation. </li></ul><ul><li>Dominant and recessive (3:1) </li></ul>
  26. 26. Dominance <ul><li>Dominant gene – Y </li></ul><ul><li>Recessive gene – y </li></ul><ul><li>Homozygous – An organism with two of the same alleles for a particular trait. </li></ul><ul><li>Heterozygous – An organism with two different alleles for a particular trait. (Yy) </li></ul>
  27. 27. Genotype and Phenotype <ul><li>Genotype – The organism’s allele pairs. </li></ul><ul><li>Phenotype – The observable characteristic or outward expression of an allele pair. </li></ul>
  28. 28. Mendel’s Law of Segregation <ul><li>States that the two alleles for each trait separate during meiosis. </li></ul><ul><li>Hybrids – Genotype Yy and has yellow seeds. </li></ul>
  29. 29. Monohybrid Cross <ul><li>A cross that involves hybrids for a single trait. </li></ul><ul><li>Genotypic ratio is 1:2:1 </li></ul><ul><li>Phenotypic ratio is 3:1 </li></ul>
  30. 30. Dihybrid Cross <ul><li>Heterozygous for two traits. </li></ul>
  31. 31. Law of Independent Assortment <ul><li>States that a random distribution of alleles occurs during gamete formation. </li></ul>
  32. 32. Punnett Squares <ul><li>Developed by Dr. Punnett in the early 1900s to predict possible offspring between two known genotypes. </li></ul>
  33. 33. Monohybrid Cross
  34. 34. Dihybrid Cross (F2 Generation)
  35. 35. 10.3 – Gene Linkage and Polyploidy <ul><li>Genetic Recombination – The new combination of genes produced by crossing over and independent assortment. </li></ul><ul><li>Genetic Recombination formula is 2 n </li></ul>
  36. 36. Gene Linkage <ul><li>Genes that are located close to each other on the same chromosome are linked and usually travel together during gamete formation. (Figure 10.14) </li></ul><ul><li>Makes an exception to Mendel’s law of independent assortment. </li></ul>
  37. 37. Polyploidy <ul><li>Polyploidy – The occurrence of one or more extra sets of all chromosomes in an organism. </li></ul><ul><li>Polyploidy formula is 3 n or greater. </li></ul><ul><li>Lethal in humans </li></ul>

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