The Meiotic Division of an Animal Cell

  1. Chromosomes begin to condense, and homologs loosely pair along their lengths, aligned gene by gene
    prophase I
  2. crossing over (the exchange of corresponding segments of DNA molecules by nonsister chromatids) is completed while homologs are in synapsis, held tightly together by proteins along their lengths
    prophase I
  3. synapsis ends in mid- (this stage), and the chromosomes in each pair move apart slightly
    prophsae I
  4. each homologous pair has one or more chiasmata, points where crossing over has occurred and the homologs are srill associated due to cohesion between sister chromatids (sister chromatid cohesion)
    prophase I
  5. centrosome movement, spindle formation, and nuclear envelope breakdown occur as in mitosis
    prophaseI
  6. In late (this phase), microtubules from one pole or the other attach to the two kinetochores, protein structures at the centromeres of the two homologs. The homologous pairs then move toward the metaphase plate
    prophase I
  7. pairs of homologous chromosomes are now arranged on the metaphase plate, with one chromosome in each pair facing each pole
    metaphase I
  8. both chromatids of one homolog are attached to kinetochore microtubules from one pole; those of the other homolog are attached to microtubules from the opposite pole
    metaphase I
  9. breakdown of proteins responsible for sister chromatid cohesion along chromatid arms allows homologs to separate
    anaphase I
  10. the homologs move toward opposite poles, guided by the spindle apparatus
    anaphase I
  11. sister chromatid cohesion persists at the centromere, causing chromatids to move as a unit toward the same pole
    anaphase I
  12. at the beginning of this phase, each half of the cell has a complete haploid set of replicated chromosomes. Each chromosome is composed of two sister chromatids; one or both chromatids include regions of nonsister chromatid DNA
    telophsae I and cytokinesis
  13. this (division of the cytoplasm) usually occurs simultaneously with this phsae, forming two haploid daughter cells
    telophse I and cytokinesis
  14. in animal cells, a cleavage furrow forms (in plant cells, a cell plate forms.)
    telophase I and cytokinesis
  15. in some species, chromosomes decondense and the nuclear envelope re-forms
    telophse I and cytokinesis
  16. no replication occurs between meiosis I and meiosis II
    telophsae I and cytokinesis
  17. a spindle apparatus forms
    prophase II
  18. in late this phase, chromosomes, each still composed of two chromatids associated at the centromere, move toward the metaphase II plate
    prophase II
  19. the chromosomes are positioned on the metaphsae plate as in mitosis
    metaphse II
  20. because of crossing over in meiosis I, the two sister chromatids of each chromsome are not genetically identical
    metaphse II
  21. the kinetochores of sister chromatids are attached to microtubules, extending from opposite poles
    metaphase II
  22. breakdown of proteins holding the sister chromatids together at the centromere allows the chromatids to separate. the chromatids move toward opposite poles as individual chromosomes
    ananpahse II
  23. nuclei form, the chromosomes begin decondensing and cytokinesis occurs
    telophase II and cytokinesis
  24. the meiotic division of one parent cell produces four daughter cells, each with a haploid set of (unreplicated) chromosomes
    telophase II and cytokinesis
  25. each of the four daughter cells genetically distinct from the other daughter cells and from the parent cell
    telophase II and cytokinesis
Author
DesLee26
ID
57809
Card Set
The Meiotic Division of an Animal Cell
Description
AP Bio
Updated