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2010-11-09 22:37:18

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  1. what does Meiosis produce?

    • Haploid gametes in the ovaries and testes in animals, and spores in plants.
    • - only in sex organs
    • - produces eggs
    • - producing sex cells
    • -produces different cells
  2. What is the difference btwn Haploid and Diploid cell?
    • Haploid cells: half genetic material, one set of chromosomes, 27 chromosomes in humans
    • Diploid cells: 2 sets of chromosomes, complete # of chromosome ( varies depending on species ), 46 chromosomes in humans
  3. Compare Mitosis to meiosis.
    • Mitosis: Skin, digestive tract, hair folicle, nails etc, growth and repair, Diploid, Identical
    • Meiosis: testes, ovaries, sporangium, sperms and eggs ( gametes ), haploid, genetically different
  4. Define homologous chromosome
    same length, centromere in same position, trait they code for is the same

  5. Define Autosomal chromosome
    " own body ", homologous chromosomes that code for your own body trait

  6. define sex chromosomes.
    • not homologous, not autosomal, XY, male, female
    • male = XY(have 22 homologous chromosomes) female = XX ( have 23 homologous chromosomes )

  7. what is the interphase of meiosis?
    results in replication of the genetic material to form chromatids, and an increase in the number of organelles, happens only once
  8. why is Meiosis I refered to as a " reduction division " ?
    b/c the homologous chromosomes, they are being separated, 6 to begin with and now 3
  9. why is meiosis II refered to as an " equation division " ?
    is like mitosis, chromosome # has not changed
  10. What is the prophase of meiosis I ?
    • chromosomes form, chromatin coling
    • - nuclear envelope breaks down
    • - centrosomes and centrioles move to oppisite ends of the cell and form spindle fibers
  11. define Synapsis
    " coming together " process that brings homologous chromosomes together ( pair up )
  12. Define Tetrad
    " 4 " chromatids, end process(result of) of a synapsis
  13. what happens in Metaphase of meiosis I ? compare to MITOSIS
    spindle fibers " change " the position of the tetrads so that they line up in the middle of the cell ( random )

    MITOSIS : no synapsis, no tetrad, individually lined up above the other

  14. What is anaphase of meiosis I ? compare to MITOSIS
    homologous chromosomes are pulled " apart " to opposite ends of the cell by the shortening of spindle fibres.

    MITOSIS: no reduction in #'s, spindle fiber shortens, centromere splits, chromatids separated, dragged to oppisite ends

  15. What happens in telephase of meiosis I ? compare to MITOSIS
    • -chromatin porms
    • - nuclear envelope reforms
    • - spindle fibers dissapear
    • - cytoplasm of the cell splits to form 2 haploid cells, each with only one set of homologous chromosomes

    MITOSIS : Diploid and identical

  16. What does Meiosis II do? compare to MITOSIS
    separates the chromatids and results in four haploid gametes

    MITOSIS : diploid cells, and body cells

  17. Summary of MITOSIS and MEIOSIS.
  18. what is the primary source of genetic variations?
    • - mutations
    • - changes in nucleotide sequence
    • causes: radiation, chemicals in environment, viruses, errors in DNA replication
  19. how does meiosis form genetically different gametes?
    • -puts them into different gametes
    • - different variations and shuffling them
  20. Define Crossing over.
    overlap, 2 chromatids overlap

  21. Define Chiasma.
    the structure that forms as a result of cross-over, overlap ( x shaped structure )
  22. define recombinant chromosomes.
    • the x shaped structure breaks and segments are exchanged, end products of cross over
    • - has maternal + paternal portions to it
  23. Define independent assortment
    happens at metaphase I, random arrangement of the homologous chromosomes in the middle of cell
  24. What is the total # of genetic combinations possible by independent assortment in humans?
    • 2^n -> haploid # of chromosomes
    • 2^2 = 4 possible outcomes

  25. Define nondisjunction in meiosis. what are the consequences?
    no separation of homologous chromosome or chromatids happening in meiosis I and meiosis II

  26. what is downs syndrome? explain cause and symptoms.
    • - extra chromosome in sex cells
    • - 47 chromosome instead of 46
    • - happens more when women is older and has kid
    • - also called trisomy 21
    • - tongue is larger, shorter
    • - body features anormal
    • - eyes not round, broader
    • - face round, flat face
    • - fingers and toes more stubby
    • - mental retardation
    • - 50% never makes it after age 1, kidney, heart problems
  27. Explain the cause and symptoms of Klinefelter syndrome.
    • - caused by nondisjunction
    • - individual that is XXy extra sex chromosome present
    • - testes smaller
    • - breast partially deveopled
    • - not much facial or chest hair
    • - hips larger than average