Meiosis and Sexual Life Cycles: Meiosis

  1. a.      Resembles mitosis
                                                                  i.      preceded by__

    What is difference?
     duplication of chromosomes

    •  a.      that it is followed by two divisions, meiosis I and IIà 4 daughter cells, each with half as many chromosomes as parent cell
  2. a.      Stage Overview
                                                                  i.      Both members of __ are duplicated and copies are sorted into __
    1.      __ make up one duplicated chromosome, but the two chromosomes of a __ are individual chromosomes inherited from different parents
    a.      __appear alike, but differ in versions of genes, called __, at corresponding __
                                                                                                                                          i.      Only involved in meiosis
    • homologous pair
    • four haploid daughter cells
    • Sister chromatids
    • homologous pair
    • Homologs
    • alleles
    • loci
  3. Meiosis does what?
                                                                  i.      Meiosis halves total number of chromosomes form two to one; each daughter cell receives one set of chromosomes
  4. Stages
    • Prophase I
    • Metaphase I
    • Anaphase I
    • Telophase I and Cytokinesis
    • Interkinesis
    • Prophase II
    • Metaphase II
    • Anaphase II
    • Telophase II and Cytokinesis
  5.                                                               i.      Prophase I 
    Chromosomes __; __loosely pair along __; aligned gene by gene
    2.      Paired homologs become physically connected to each other along their lengths by protein structures, called the __; this state is called __
    3.      __ , a genetic rearrangement between __involving __, begins during the __and __; completed while homologs are in __

    • homologs
    • lengths
    • synaptonemal complex
    • synapsis
    • Crossing over
    • nonsister chromatids
    • exchange of segments of DNA molecules
    • pairing
    • synaptonemal complex formation
    • synapsis
  6. Prophase I cont.
    __(3)__ occur as in mitosis
    2.      Late prophase I: microtubules from one pole or the other attach to two __, protein structures at the centromeres of the two __
    a.      Homologous pairs move towards __
    • Centrosome movement, spindle formation, and nuclear envelope breakdown 
    • kinetochores
    • homologs
    • metaphase plate
  7.                                                               i.      Metaphase I
    1.      Pairs of homologous chromosomes arranged at __, with one chromosome in each pair facing each pole
    2.      Both __of one homolog attached to __form one pole; those of the other homolog are attached to microtubules from the opposite pole
    • metaphase plate
    • chromatids
    • microtubules
  8.                                                               i.      Anaphase I
    1.      Breakdown of proteins responsible for __ along chromatid arms allow __ to separate
    2.      __move towards opposite poles, guided by __

    3.      __ persists at __, causing chromatids to move as a unit toward the same pole
    • sister chromatid cohesion
    • homologs
    • Homologs
    • spindle apparatus
    • Sister chromatid cohesion
    • centromere
  9.                                                               i.      Telophase I and Cytokinesis
    1.      Beginning of Telophase I: each half of cell has complete __set of duplicated chromosomes
    a.      Each chromosome composed of two __; one or both chromatids include __

    2.      __occurs simultaneously, forming two __ daughter cells
    a.      Animal cells: __
    b.      Plant cells: __c.       Some species: chromosomes condense and nuclear envelopes form
    d.      No chromosome duplication occurs between meiosis I and meiosis II: __
    • haploid
    • sister chromatids
    • nonsister chromatid DNA
    • Cytokinesis
    • haploid
    • cleavage furrow
    • cell plate
    • interkineses
  10. ii. Prophase II
    1. __ forms
    2. In late prophase II, chromosomes still composed of two __associated at __move toward __
    • Spindle apparatus
    • chromatids
    • centromere
    • metaphase II plate
  11.                                                               i.      Metaphase II
    1.      Chromosomes on __
    2.      Because of __ in meiosis I, two sister chromatids are not __
    3.      __of sister chromatids attached to __extending from opposite poles
    • metaphase plate
    • crossing over
    • genetically identical
    • Kinetochores
    • microtubules
  12.                                                               i.      Anaphase II
    1.      Breakdown of proteins holding the sister chromatids together at __allows chromatids to separate
    a.      __move toward opposite poles as individual chromosomes
    • centromere
    • Chromatids
  13.                                                               i.      Telophase II and Cytokinesis
    1.      __form, the chromosomes begin decondensing
    2.      __occurs
    3.      Meiotic division of one parent cell produces __daughter cells, each with a haploid set of unduplicated chromosomes
    4.      Four daughters genetically __from each other and parent cell
    • Nuclei
    • Cytokinesis
    • four
    • distinct
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Meiosis and Sexual Life Cycles: Meiosis