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Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
Meiosis gamete production with turning point
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Meiosis gamete production with turning point

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  • Formula: 2 n Human chromosomes: 2n = 46 n = 23 2 23 = ~8 million combinations
  • What are they? Crossing over in prophase I independent assortment in metaphase I random fertilization
  • Transcript

    • 1. Reduction-Division Genetic Recombination
    • 2. <ul><li>The form of cell division by which GAMETES , with HALF the number of CHROMOSOMES , are produced. </li></ul><ul><li>DIPLOID (2n)  HAPLOID (n) </li></ul><ul><li>Meiosis is SEXUAL reproduction. </li></ul><ul><li>TWO divisions ( MEIOSIS I and MEIOSIS II ). </li></ul>
    • 3. <ul><li>Sex cells divide to produce GAMETES (sperm or egg) . </li></ul><ul><li>Gametes have HALF the # of chromosomes. </li></ul><ul><li>Occurs only in GONADS (testes or ovaries). </li></ul><ul><li>Male: SPERMATOGENESIS </li></ul><ul><li>Female: OOGENESIS </li></ul>
    • 4. 2n=46 human sex cell diploid (2n) n=23 n=23 Meiosis I n=23 n=23 n=23 n=23 sperm haploid (n) Meiosis II
    • 5. Polar Bodies (die) 2n=46 human sex cell diploid (2n) n=23 n=23 Meiosis I n=23 egg Haploid (1n) Meiosis II
    • 6. <ul><li>Similar to mitosis interphase . </li></ul><ul><li>CHROMOSOMES replicate in the S phase. </li></ul><ul><li>Each duplicated chromosome consist of two identical sister CHROMATIDS attached at their CENTROMERES . </li></ul><ul><li>CENTRIOLE pairs also replicate. </li></ul>
    • 7. <ul><li>Nucleus and nucleolus visible . </li></ul>nuclear membrane nucleolus cell membrane chromatin
    • 8. <ul><li>Cell division that reduces the chromosome number by one-half. </li></ul><ul><li>Four phases : </li></ul><ul><li>a. prophase I </li></ul><ul><li>b. metaphase I </li></ul><ul><li>c. anaphase I </li></ul><ul><li>d. telophase I </li></ul>Prophase I
    • 9. <ul><li>Longest and most complex phase (90%). </li></ul><ul><li>Chromosomes condense. </li></ul><ul><li>Synapsis occurs: homologous chromosomes come together to form a tetrad . </li></ul><ul><li>Tetrad is two chromosomes or four chromatids (sister and non-sister chromatids). </li></ul>
    • 10.
    • 11. Homologous chromosomes sister chromatids sister chromatids Tetrad
    • 12. <ul><li>Pair of chromosomes ( maternal and paternal ) that are similar in shape and size . </li></ul><ul><li>Homologous pairs ( tetrads ) carry genes controlling the same inherited traits . </li></ul><ul><li>Each locus (position of a gene) is in the same position on homologues. </li></ul><ul><li>Humans have 23 pairs of homologous chromosomes: </li></ul><ul><li>a. 22 pairs of autosomes </li></ul><ul><li>b. 1 pair of sex chrom osomes </li></ul>LOCI
    • 13. Paternal Maternal eye color locus eye color locus hair color locus hair color locus
    • 14. <ul><li>Crossing over may occur between non-sister chromatids at sites called chiasmata . </li></ul><ul><li>Crossing over : segments of nonsister chromatids break and reattach to the other chromatid . </li></ul><ul><li>Chiasmata (chiasma) are where chromosomes touch each other and exchange genes ( crossing over .) </li></ul>
    • 15. variation nonsister chromatids chiasmata: site of crossing over Tetrad
    • 16.
    • 17. XX chromosome - female XY chromosome - male
    • 18. <ul><li>Homologs separate </li></ul>Meiosis I
    • 19. <ul><li>Nucleus & Nucleolus disappear </li></ul><ul><li>Spindle forms </li></ul><ul><li>Chromosomes coil & Synapsis (pairing) occurs </li></ul><ul><li>Tetrads form & Crossing over Occurs </li></ul>TETRAD centrioles spindle fiber aster fibers
    • 20. <ul><li>Shortest phase </li></ul><ul><li>Tetrads align on the metaphase plate ( equator ). </li></ul><ul><li>Independent assortment occurs – chromosomes separate randomly </li></ul><ul><li>Formula: 2 n </li></ul><ul><li>Example: 2n = 4 </li></ul><ul><li>then 1n = 2 thus 2 2 = 4 combinations </li></ul>Gametes
    • 21. metaphase plate OR metaphase plate
    • 22. <ul><li>In terms of Independent Assortment -how many different combinations of sperm could a human male produce? </li></ul>
    • 23. <ul><li>Formula: 2 n </li></ul><ul><li>Human chromosomes: 2n = 46 </li></ul><ul><li>n = 23 </li></ul><ul><li>2 23 = ~8 million combinations </li></ul>
    • 24. <ul><li>Homologous chromosomes separate and move towards the poles. </li></ul><ul><li>Sister chromatids remain attached at their centromeres . </li></ul>
    • 25. Homologs separate
    • 26. <ul><li>Each pole now has haploid (1n) set of chromosomes . </li></ul><ul><li>Cytokinesis occurs and two haploid daughter cells are formed. </li></ul>
    • 27. cytokinesis
    • 28. <ul><li>Autosomes </li></ul><ul><li>Gonads </li></ul><ul><li>Nuclei </li></ul><ul><li>Ovaries </li></ul>0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33
    • 29. <ul><li>1 gamete </li></ul><ul><li>2 gametes </li></ul><ul><li>3 gametes </li></ul><ul><li>4 gametes </li></ul><ul><li>2 new cells </li></ul>0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34
    • 30. <ul><li>Mitosis </li></ul><ul><li>Spermatogenesis </li></ul><ul><li>Oogenesis </li></ul><ul><li>Binary fission </li></ul>0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34
    • 31. <ul><li>10 </li></ul><ul><li>23 </li></ul><ul><li>46 </li></ul><ul><li>50 </li></ul>0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34
    • 32. <ul><li>10 </li></ul><ul><li>23 </li></ul><ul><li>46 </li></ul><ul><li>50 </li></ul>0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34
    • 33. <ul><li>Sperm </li></ul><ul><li>Prokaryotes </li></ul><ul><li>Chromosomes </li></ul><ul><li>Polar bodies </li></ul>0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34
    • 34. <ul><li>Chromosomes </li></ul><ul><li>Chromatids </li></ul><ul><li>Centromeres </li></ul><ul><li>Kinetochores </li></ul>0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34
    • 35. <ul><li>Chromosome number halved </li></ul><ul><li>Chromosome number doubled </li></ul><ul><li>4 new cells </li></ul><ul><li>Preparations for meiosis II </li></ul>0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34
    • 36. <ul><li>Synapsis </li></ul><ul><li>Chiasma </li></ul><ul><li>Haploidism </li></ul><ul><li>Crossing over </li></ul>0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34
    • 37. <ul><li>Prophase I </li></ul><ul><li>Metaphase I </li></ul><ul><li>Anaphase I </li></ul><ul><li>Telophase I </li></ul>0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34
    • 38. <ul><li>Prophase I </li></ul><ul><li>Metaphase I </li></ul><ul><li>Anaphase I </li></ul><ul><li>Telophase I </li></ul>0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34
    • 39. <ul><li>Prophase I </li></ul><ul><li>Metaphase I </li></ul><ul><li>Anaphase I </li></ul><ul><li>Telophase I </li></ul>0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34
    • 40. <ul><li>Prophase I </li></ul><ul><li>Metaphase I </li></ul><ul><li>Anaphase I </li></ul><ul><li>Telophase I </li></ul>0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34
    • 41. <ul><li>Sister Chromatids Separate </li></ul>Meiosis II
    • 42. <ul><li>No Interphase II or very short </li></ul><ul><li>No DNA Replication </li></ul><ul><li>Remember: Meiosis II is similar to mitosis </li></ul>
    • 43. <ul><li>Same as Prophase in mitosis </li></ul>
    • 44. <ul><li>Same as Metaphase in mitosis </li></ul>metaphase plate metaphase plate
    • 45. <ul><li>Same as Anaphase in mitosis </li></ul><ul><li>SISTER CHROMATIDS separate </li></ul>
    • 46. <ul><li>Same as Telophase in mitosis. </li></ul><ul><li>Nuclei and Nucleoli reform. </li></ul><ul><li>CYTOKINESIS occurs. </li></ul><ul><li>Remember: FOUR HAPLOID DAUGHTER cells are produced. </li></ul><ul><li>Called GAMETES (eggs and sperm) </li></ul>1n Sperm cell fertilizes 1n egg to form 2n zygote
    • 47.
    • 48. 2n=4 sex cell diploid (2n) n=2 n=2 meiosis I n=2 n=2 n=2 n=2 sperm haploid (n) meiosis II
    • 49.
    • 50. <ul><li>Also known as GENETIC RECOMBINATION </li></ul><ul><li>Important to population as the raw material for NATURAL SELECTION. </li></ul><ul><li>All organisms are NOT alike </li></ul><ul><li>Strongest “ most fit” survive to reproduce & pass on traits </li></ul>
    • 51. <ul><li>What are the 3 sources of genetic recombination or variation? </li></ul>
    • 52. <ul><li>CROSSING OVER (prophase I) </li></ul><ul><li>INDEPENDENT ASSORTMENT (metaphase I) </li></ul><ul><li>RANDOM FERTILIZATION </li></ul>
    • 53. <ul><li>A cell containing 20 chromosomes (diploid) at the beginning of meiosis would, at its completion, produce cells containing how many chromosomes ? </li></ul>
    • 54. <ul><li>10 chromosomes (haploid or 1n) </li></ul>
    • 55. <ul><li>A n organized picture of the chromosomes of a human arranged in pairs by size from largest to smallest. </li></ul><ul><li>P airs 1-22 called AUTOSOMES </li></ul><ul><li>L ast pair are SEX CHROMOSOMES </li></ul>Male - XY
    • 56. Female - XX
    • 57. Female - XX Down Syndrome – Trisomy 21
    • 58. <ul><li>The fusion of a sperm and egg to form a zygote . </li></ul><ul><li>A zygote is a FERTILIZED EGG </li></ul>n=23 egg sperm n=23 2n=46 zygote
    • 59. <ul><li>A cell containing 40 chromatids at the beginning of meiosis would, at its completion, produce cells containing how many chromosomes ? </li></ul>
    • 60. <ul><li>10 chromosomes </li></ul>
    • 61. <ul><li>Chromosomes </li></ul><ul><li>Prophase </li></ul><ul><li>DNA Replication </li></ul><ul><li>Chromatids </li></ul>20 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
    • 62. <ul><li>Prophase II </li></ul><ul><li>Metaphase II </li></ul><ul><li>Anaphase II </li></ul><ul><li>Telophase II </li></ul>20 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
    • 63. <ul><li>Prophase II </li></ul><ul><li>Metaphase II </li></ul><ul><li>Anaphase II </li></ul><ul><li>Telophase II </li></ul>20 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
    • 64. <ul><li>Prophase II </li></ul><ul><li>Metaphase II </li></ul><ul><li>Anaphase II </li></ul><ul><li>Telophase II </li></ul>20 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
    • 65. <ul><li>Prophase II </li></ul><ul><li>Metaphase II </li></ul><ul><li>Anaphase II </li></ul><ul><li>Telophase II </li></ul>20 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
    • 66. <ul><li>Natural selection </li></ul><ul><li>Mutations </li></ul><ul><li>Homogeneous populations </li></ul><ul><li>Isolation </li></ul>20 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
    • 67. <ul><li>1 </li></ul><ul><li>2 </li></ul><ul><li>3 </li></ul><ul><li>4 </li></ul><ul><li>5 </li></ul>1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 20
    • 68. <ul><li>10 </li></ul><ul><li>25 </li></ul><ul><li>50 </li></ul><ul><li>100 </li></ul>20 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
    • 69. <ul><li>Somatic cells </li></ul><ul><li>Autosomes </li></ul><ul><li>Epithelial cells </li></ul><ul><li>Sickle cells </li></ul>20 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
    • 70. <ul><li>Embryo </li></ul><ul><li>Zygote </li></ul><ul><li>Haploid cell </li></ul><ul><li>Mutation </li></ul>20 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

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