BIOL 100 exam 2 - CH 19

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  1. Chromosome
    DNA and specialized proteins, primarily histones

    composed of chromatin
  2. Gene
    part of the DNA that directs synthesis of a specific protein

    determines the trait (i.e. eye color)
  3. Somatic Cells
    all body cells except for gametes (egg and sperm).
  4. Homologous Chromosome Pair
    a pair of chromosomes that bear genes for the same traits.

    one member of each pair came from each parent

    they are the same size, shape, and line up with one another during meiosis I
  5. Diploid
    the condition of having two sets of chromosomes in each cell

    i.e. somatic (body) cells
  6. Sex Chromosomes
    the pair of chromosomes involved in determining gender - x and y
  7. Autosomes
    the 22 pairs of chromosomes (excluding the sex chromosomes) that determine the expression of most of the inherited characteristics of a person
  8. Mitosis
    cell division of somatic cells

    usually divided into prophase, metaphase, anaphase, and telophase
  9. Cell Cycle
    the entire sequence of events that a cell goes through from its origin in the division of a parent cell through is own division into 2 daughter cells

    consists of 2 major phases: interphase and cell division
  10. Interphase
    period of cell growth

    3 stages:

    • G1 (GAP 1)
    • - - - metabolically active
    • S (synthesis)
    • - - - DNA is replicated
    • G2 ( GAP 2)
    • - - - organize & prep for cell division
    • - - - make proteins to prep for mitosis
  11. S - Interphase
    In mitosis:

    - synthesis of water

    - DNA is replicated
  12. G1 of Interphase - Gap 1
    In mitosis:

    - Growth of cell

    - metabolically active
  13. G2 (Gap 2) of Interphase
    in Mitosis:

    • - organize and prep for division
    • - centrioles replicate
    • - make proteins to prep for cell division
  14. Centromere
    attachment point for spindle fibres

    the region of a replicated chromosome at which sister chromatids are held together until they separate during cell division
  15. Chromatid
    one of the 2 identical replicates of a duplicated chromosome

    • - unwound thread of DNA
    • - Protein
    • - - - histones used to package DNA

    packaged into nucleosome
  16. Prophase
    in mitosis, the phase when:

    • - chromosomes condense
    • - nuclear envelope disintigrates
    • - centrioles migrate to opposite poles
    • - spindle fibres attach to centrioles
  17. Metaphase I
    phase of Meiosis

    • - Chromosomes line up along the equator w/ homologue
    • - - they line up in pairs (matched sets) 2x2

    - microtubules attach to centromere of homologous chromosome
  18. Metaphase
    phase where chromosomes line up along equator
  19. Anaphase
    in mitosis, the shortest phase and when:

    • - centromeres split
    • - sister chromatids split
    • - spindle fibers pull chromosomes to poles
  20. Anaphase I
    in Meiosis

    • - Homologous chromosomes separate
    • - - (matched sets separate)

    * phase that makes the # of chromosomes reduced to 23 (from 46)
  21. Telophase I
    in meiosis

    - homologous chromosomes finish separating

    - cytokinesis

    - nucleus forms
  22. Telophase
    in mitosis, the phase when:

    • - Chromosomes finally get to separate poles
    • - chromosomes decondense
    • - nuclear envelope reforms
    • - cytokenisis (division of cytoplasm) is complete
  23. Cytokinesis
    separation into 2 cells with 1/2 the original number of chromosomes.

    occurs during telophase
  24. Karyotype
    the arrangement of chromosomes based on physical characteristics i.e. length and location of the centromere

    can be checked for defects in number or structure of chromosomes
  25. Haploid
    the condition of having one set of chromosomes, as in eggs and sperm
  26. Meiosis
    sex cell division: separatation of homologues

    • - 2 step process (M1 and M2)
    • - Results in 4 genetically different "daughter cells"
    • - production of male and female gametes
  27. Synapsis
    coming together of homologous chromosomes that occurs during prophase 1 of meiosis.

    occurs to form a tetrad
  28. Crossing Over
    exchange of alleles between non-sister chromatids

    - allows for genetic recombination/variability

    occurs within chiasmata (overlaping)

    - DOES NOT always happen
  29. Independent Assortment
    - positioning of homologous pairs is random

    - resulting daughter cells have combination of mom and dad chromosomes

    an important source of genetic variation
  30. Nondisjunction
    During Anaphase I or II . . .

    • - pair of homologues Don't Separate
    • - sister chromatids Don't Separate

    results in sex cells with an abnormal number of chromosomes
  31. Trisomy
    a condition in which there are 3 representatives of a chromosome instead of only 2 representatives
  32. Monosomy
    a condition in which there is only 1 representative of a chromosome instead of 2 representatives
  33. Number Reduction and Genetic Recombination
    2 Purposes of meiosis
  34. Number Reduction
    in meiosis: n+n=2n

    - allows 2 cells to come together to form 1 diploid

    - otherwise there will be polyploidy condition
  35. Genetic Recombination/Variability
    in meiosis:

    - crossing over

    - independent assortment

Card Set
BIOL 100 exam 2 - CH 19
CH 19: Chromosomes and Cell Division
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