Chapter 13: Meiosis and sexual cycles

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Chapter 13: Meiosis and sexual cycles
2013-07-26 00:27:40
Biology 1610

Meiosis and sexual cycles
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  1. heredity
    The transmission of traits from one generation to the next.
  2. variation
    differences that arise from parent to offspring
  3. genetics
    scientific study of heredity & hereditary variation
  4. genes
    inherited from parentcodes for specific proteinresponsible for traits
  5. gametes
    reproductive cells of sexual reproduction haploid (1/2 of chromosomes)
  6. somatic cells
    cells of body except gameteshumans have 46 chromosomes in these
  7. locus
    gene's specific location along length of chromosome
  8. asexual reproduction
    single individual is sole parentcopies of all genes to offspringno fusion of gametes
  9. clone
    genetically identical individuals
  10. sexual reproduction
    1 gamete each from 2 different parents fuse to form offspring
  11. life cycle
    generation to generation sequence of stages in reproductive history of an organism
  12. homologs
    homologous chromosomes.

    Two chromosomes composing a pair have the same length, centromere position, staining pattern
  13. karotype
    number and appearance of chromosomes in nucleus of eukaryotic cell
  14. sex chromosome
    X and Y chromosomes that determine offspring's sex
  15. autosomes
    non-sex determining chromosomes
  16. diploid cell
    any cell with 2 sets of chromosomes denoted as 2n, humans 2(23)=46
  17. haploid cell
    gametes with single set of chromosomesdenoted as n, humans n=23
  18. fertilization
    fusion of haploid cells' nuclei that produces zygote
  19. zygote
    haploid cell that results from fertilization
  20. alternation of generations
    plants & some algae diploid & haploid stages are multicellular.

    sporophytemulticellular diploid stage.

    spores meiosis in sporphyte produces haploid spores.

    gametophyte multicellular haploid stage produced by spore dividing mitotically
  21. meiosis
    cell division that reduces the number of sets of chromosomes from two to one.

    reduces chromosome count from diploid to haploid.

    Interphase followed by 2 consecutive cell divisionsmeiosis I and meiosis II

    4 daughter cells each with only half as many chromosomes as parent
  22. sister chromatid cohesion
    association of sister chromatids all along length
  23. Prophase I
    chromosomes condense homologs loosely pair along lengths.

    synapsis occurssynaptonemal complex physically connect paired homologs.

    crossing over genetic rearrangement between nonsister.

    chromatids involves exchange of corresponding DNA segments.

    chiasmata exist at point where crossover occurred.

    centrosome movement, spindle formation, nuclear envelope breakdown.

    proteins attach to kinetochores.

    homologs movetoward plate
  24. alleles
    loci for a gene on a chromosome

    different versions of the same gene e.g. coding for eye color
  25. Prophase I
    The nuclear membrane breaks apart, chromosomes condense and form homologous chromosomes. Crossing over may occur and cause offspring diversity.
  26. Meiosis I
    The first of two consecutive cell divisions that produces a cell with half the number of chromosomes as the parent cell
  27. Meiosis II
    The second consecutive cell division
  28. crossing over
    haploid cells that give rise to multicellular individual without fusing with another cell. divides mitotically to generate a multicellular haploid stage called gametophyte

    genetic rearrangement between nonsister.
  29. Metaphase I
    Homologous pairs line up in center, Spindle fibers attach to the chromosomes.
  30. Anaphase I
    Homologus pairs seperate and move to opposite ends of the cell.
  31. Telophase I
    Nuclear membrane forms around each set of chromosomes, the cytoplasm divides, forming two new daughter cells
  32. Prophase 2
    Nuclear membrane breaks apart.
  33. Metaphase II
    Sister chromatids line up along the middle of the cell.
  34. Anaphase II
    Sister chromatids separate and are pulled to the opposite end of the cells.
  35. Telophase II
    Chromosomes are single stranded, end up with four new cells, cells are Haploid, nucleus does reappear.
  36. Recombinant Chromosomes
    Individual chromosomes that carry genes derived from two different parents
  37. sporophyte
    the multicellular diploid stage of the alternation of generations. goes through meiosis to produce spores
  38. chiasmata
    criss crossed regions where crossing over has occured.
  39. gametophyte
    alternation of generations, the multicellular haploid form that produces haploid gametes by mitosis. The haploid gametes unite and develop into sporophyte