ch 11

  1. Asexual Reproduction
    Offspring are genetically identical to original cell or organism

    Involves inheritance of all genes from one parent
  2. Asexual reproduction produces new cells in order to ..???
    produce new unicellular cells

    heal wounds and replace damaged cells/tissues

    grow and develop
  3. what are mostly sexual


  4. What are mostly asexual


  5. Asexual reproduction - cell replication ='s
    (Diploid --->diploid)

    • only one parent cell
    • offspring are genetically identical to parent
    • DNA replicated and evenly divided so 2 daughter cells get same DNA, TWO copies of each gene ='s Mitosis
  6. Sexual reproduction ='s

    • offspring are genetically different from one another and from parents
    • Gamete are combinded from two parents
    • DNA replicated and divide up so each of 4 daughter cells gets ONE copy of each gene ='s MEIOSIS
  7. Genetic Variation in Population='s
    Shuffling of gene forms (alleles)
  8. DNA from two parents ='s
    random gamete fusion, mating choice
  9. How many chromosomes does a person have ??
  10. Life cycles of sexually reproducing organisms involve....??
    alternation of haploid and diploid stages
  11. Some life cycles include longer ______ phases and longer ____phases???
    Longer diploid and haploid phases
  12. In most animals _______ state dominates
    Diploid state 
  13. When the Diploid statedomintate what happens to the Zygote
    Zygote first undergoes mitosis to produce diploid cells
  14. What happens later in the life cycle to diploid cells??
    Diploid cells undergo meiosis to produce haploid gametes
  15. What do Gametes do when they combine??
    Gametes combine to regenerate diploid zygote
  16. What are the products of Mitosis??
    • Diploid cells
    • 2 copies of each autosome (1-22)
    • 2 sex chromosomes: 2X or (1X +1Y)
  17. What are the products of Meiosis???
    • Haploids cells
    • 1 copy of each autosome (1-22)
    • 1 sex chromosome: 1X or 1Y
  18. Meiosis ='s
  19. Gametogenesis
    specialized form of cell division in gonads to produce gametes
  20. What does gametogenesis reduce??
    Reduces number of chromosomes in each cell by one-half.
  21. In Gametogenesis chromosomes come in ??
    Homologous pairs
  22. Diploid cells??
    Human somatic cells have 22 pairs of autosomes, and one pair of sex chromosomes (2X or X+Y)
  23. Haploid cells???
    human gametes have one of each pair (22 autosomes plus 1X or 1Y)
  24. What are the 4 phases in Meiosis I
    • Prophase I
    • Metaphase I
    • Anaphase I
    • Telophase I
  25. What happens in Prophase I
    homologous pairs come together
  26. What happens to Metaphase I
    homologous pairs line up at equator
  27. what happens in Anaphase I
    homologous pairs separate
  28. What happens in Telophase I
    nuclear envelope reforms
  29. Meiosis II occurs when 
    after an nterval of variable length
  30. What is the difference between Anaphase I in Meiosis I and Anaphase in Mitosis
    in Anaphase I Microtubules pull homologous chromosomes apart and sister chromatids are held together

    In Anaphase in Mitosis microtubules pull sister chromatids apart
  31. What is the difference in Metaphase I in Meiosis I and Metaphase in Mitosis
    • Metaphase I:
    •     -Chiasmata hold homologues together
    •     -the kinetochores of sister chromatids fuse and function as one
    •     -microtubules can attach to only one side of each centromere

    • Metaphase:
    •     -Homologues do NOT pair
    •     -kinetochores of sister chromatids remain separate
    •     -microtubules attach to both kinetochores on opposite side of centromere
  32. What is the Final result of meiosis
    • -Four cells contain haploid sets of chromosomes
    • -in animals, develop directly into gametes
    • -in plants, fungi, divide mitotically 
    •     -produce greater number of gametes
    •     -Adults with varying numbers of gametes
  33. What does Genetic Variation in Population mean??
    Shuffling of gene forms (alleles)  
  34. What happens when you get DNA from two parents
    random gamete fusion, mating choice
  35. What happens Early Prophase I
    ='s Synapsis 

    Homologous chromosomes closely associate (sunaptonemal complexes)

    -Tetrad= bivalent
  36. Crossing Over
    exchange of equivalent portions of chromosomes between members of a homologus pair
  37. What does Crossing over result in ???
    Results in new types of gametes being formed
  38. What is the Crossing Over Process in Prophase I ??
    • 1. Homologous chromsosome
    • 2. Chiasma (non sister chromatids join at chiasmata)
    • 3. Recombinant chromatids 
    •     -alleles of genes that were formerly on separate homologues can now be found on the same homologue
  39. What does Genetic Recombination =???
    ='s production of new combinations ofalleles due to crossing over
  40. Crossing Over ='s 
    • Recobination 
    •     -phrophase I: homologous pairs exchange genetic information 
  41. Random alignment -----> ______???
    • Independent Assorment
    •     - Metaphase I
  42. What is Metaphase 1 
    radom alignment of homologue, which homologue goes to which cell
  43. What are the Key points in Meiosis??
    • 1. Synapsis and crossing over
    • 2. sister chromatids remain joined at their centromeres throughout meiosis I
    • 3. Kinetochores of sister chromatids attach to same pole in meiosis I
    • 4. DNA replication is suppressed btw meiosis I and Meiosis II
  44. What happens in Nondisjunction ??
    • -Chromosome pairs fail to separate during meiosis I
    • - Chromosomes fail to separate at centromere during meiosis II

    • Results:
    • -gametes with incorrect chromosome number
    • -zygote with incorrect chromosome number
  45. Nondisjunction
    Accidents in meiosis can alter chromsome number 

    Failure of homologues or sister chromatids to separate properly during meiosis
  46. Who is at risk for Nondisjunction??
    Older women 

    • -increased incidence of trisomic embryos in older women
    • -Meiosis begin in all eggs b4 the woman is born, and finishes as each egg matures in the monthly cycle following puberty
    • -Eggs of older women have been "within" meiosis longer
  47. Aneuploidy
    gain or loss of chromosome
  48. Monosomy
    Loss of chromosome
  49. Trisomy
    Gain of chromosome
  50. Why do we typically only see trisomy 13, 15, 18, 21, and 22 births??
    Some of the smalles autosomes can present as 3 copies and allow individuals to survive 

    • -13,15,18- severe defects, die w/in a few months to year
    • -21 and 22- can survive to adulthood
  51. What does an extra copy of a chromosome 21 cause??
    Down Syndrome

    Trisomy 21: 3 copies of chromosome 21

    most common human chromosome abnormality (1/700 births)
  52. What does an extra copy of Chromosome 18 cause??
    Edwards Syndrome

    • Trosomy 18: 3 copies of chromosome 18
    •     -1/3,000 births
    •     - incidence increases w/ maternal age
    •     -50% are stillborn, 5-10% live to 1 year, 1% live to 10 years, rare to survive to adult
  53. What happens when there is an extra copy of chromosome 13??
    Patau syndrome

    • Trisomy 13: 3 copies of chromosome 13
    •    -incidence increases w/ maternal age
    •    - 18% survive beyond 1 year, rare to survive to adult
  54. Nondisjunction of sex chromosomes generally do not experience ______???
    Do not generally experience severe developmental abnormalities

    Individuals have somewhat abnormal features, but often reach maturity and in some cases may be fertile
  55. What are examples on Nondisjunction of sex chromosomes??
    • XXX-triple X females
    • XXY-males (Klinefelter syndrome)
    • XO-females (Turner syndrome)
    • OY-nonviable zygotes
    • XYY- males (jacob syndrome)
  56. XXX ='s
    Triple X females
  57. XXY ='s
    Males (klinefelter syndrome)
  58. XO ='s
    females Turner Syndrome
  59. OY ='s
    nonvialbe zygotes
  60. XYY ='s
    Males Jacobs syndrome
  61. Chromosomal abnormalities result from errors in ______???
    meiosis, mitosis, DNA replication, environmental damage
  62. What are breakages and rejoining of chromosome segments called???
    • Deletion
    • Duplication
    • Inversion
    • Translocation
  63. Breakage and rejoining of chromosome segments can cause ...???
    Gametes: birth defects/spontaneous abortion

    Somatic cells: cancer
Card Set
ch 11
bio exam2 ch 11