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5 Written questions

5 Matching questions

  1. prophase
  2. G1 phase
  3. oogenisis
  4. Haploid dominant species
  5. Polar micro tubulues
  1. a a cell prepares to divide
    The cell reaches a restriction point and is committed on a pathway to cell division
  2. b The production of egg cells

    In female animals, it occurs in the ovaries

    Early in development, diploid oogonia produce diploid primary oocytes
    In humans, for example, about 1 million primary occytes per ovary are produced before birth

    Takes place in the ovaries
    Start with the oogonia (2n)  undergoes mitosis and creates primary oocytes (Diploid)
    These enter into meiotic 1 division. The division is stalled at prophase 1
    It waits under the female is sexually mature to proceed to the rest of the stages

    The primary oocytes initiate meiosis I
    However, they enter into a dormant phase
    They are arrested in Prophase I until the female becomes sexually mature
    At puberty, primary oocytes are periodically activated to progress through meiosis I
    In humans, one oocyte per month is activated
    The division in meiosis I is asymmetric producing two haploid cells of unequal size
    A large secondary oocyte oocyte
    A small polar body

    The secondary oocyte enters meiosis II but is quickly arrested in it
    It is released into the oviduct
    An event called ovulation
    If the secondary oocyte is fertilized
    The haploid egg and sperm nuclei then fuse to created the diploid nucleus of a new individual
    During the 1st meiotic division, it is not symmetrical.
    1 secondary oocyte (Very large)
    1 polar body ( will sometimes undergo 2nd meiotic division and sometimes it wont)
    Can have 1 egg cell and 1 polar body or 1 egg cell or 3 polar bodies
  3. c 1) Nuclear envelope dissociates into smaller vesicles
    2)Centrosomes separate to opposite poles
    3) The mitotic spindle apparatus is formed
    Composed of mircotubules (MTs)

    Condensation of chromosome, compaction BEGINS as prophase
    All of the euchromatic regions will become heterochromatic
    Nucleolous synthesize ribosomalRNA - as chromosomes compact, the nucleolous disappears
    Nuclear membrane is converted into vesicles
    Different microtubulues are made - spindle apparatus
    Aster microtubulues - propagate towards palama membrane, hold the 2 centrosomes in position
    Polar micro tubulues - polymerize toward chromosomes. Push centrosomes away from each other
    Kinetochore microtubulue - come and binds to kinetochore, it is not yet bound in the prophase stage, it is just moving towards the kinetochore protein at this stage
  4. d polymerize toward chromosomes. Push centrosomes away from each other, positioning spindle apparatus
  5. e spends most of its life in its haploid state
    Fungi

5 Multiple choice questions

  1. The life cycles of plant species alternate between two generations
    Haploid, which is termed the gametophyte
    Diploid, which is termed the sporophyte
    Meiosis produces haploid cells called spores
    Spores divide by mitosis to produce the gametophyte
    Alternate between gametophyte and sporeophyte
    Gametophyte (haploid)
    Sporophyte (diploid)
    Alternation of generation plant have huge sporophyte and tiny gametophytes
    Angiosperm - plant that produces flowers and seeds
    - spermatogenesis takes place in the anther
    - they hold the pollen grains
    -
    Meosis
    Creates 4 microspores
    They undergo mitosis
    You end up with 8 cells.
    There is a tube cell and a generative cell (which will under go mitosis and create 2 sperm cells after the pollen grain falls on the stigma nuclei)
    The tube and generative cell have a thick cell wall that creates the pollen grain
    Female 
    Megasporocyte undergoes meiosis  creates 4 megaspores but 3 degenerate
    The megaspore will undergo 3 rounds of mitotic division with asymmetrical cytokenisis  this leads to 7 cells instead of the expected 8
    Only 7 rounds of cytokenesis
    1 central cell with 2 haploid nuclei, then you have 3 antipodal cells and 2 synergid cells. This all results from the 3 mitotic divisions.
    1 cell does not undergo cytokenesis  you have 2 haploid nuclei in 1 central cell. This is called the endosperm (provides nutrition)
    Once the pollen grain falls on the stigma, the tube cell crates the pollen tube, the sperm will fertilize the egg and one will fertilize the central cell. This creates a zygote and an ensodsperm. The first fertilization is btw the egg and sperm
    Ovary = seed
  2. areas of contact that persist and keep moving toward the ends are called chiasmata.
  3. One purpose of cell division is asexual reproduction
    A second important reason for cell division is multicellularity
    Plants, animals and certain fungi are derived from a single cell that has undergone repeated cell divisions
    For example
    Humans start out as a single fertilized egg
    End up as an adult with several trillion cells
  4. The field of genetics that involves the microscopic examination of chromosomes
    A cytogeneticist typically examines the chromosomal composition of a particular cell or organism
  5. Enzymes allow for crossing over. There is a recombination nodule. Enzymes identify areas of homology and allow for exchange.

5 True/False questions

  1. interphase nucleusIn actively dividing cells, G1, S and G2 are collectively known as interphase
    A cell may remain for long periods of time in the G0 phase
    A cell in this phase has
    Either postponed making a
    decision to divide
    Or made the decision to never
    divide again
    Terminally differentiated cells
    (e.g. nerve cells)

          

  2. Metaphase IBivalents are organized along the metaphase plate
    Pairs of sister chromatids are aligned in a double row, rather than a single row (as in mitosis)
    The arrangement is random with regards to the (blue and red) homologues
    Furthermore
    A pair of sister chromatids is linked to one of the poles
    And the homologous pair is linked to the opposite pole

          

  3. Anaphase IThe connection holding the sister chromatids together is broken
    Each chromatid, now an individual chromosome, is linked to only one pole
    As anaphase proceeds
    Kinetochore MTs shorten
    Chromosomes move to opposite poles
    Polar MTs lengthen
    Poles themselves move further away from each other
    The kinetochore microtubulues de polymerize (shorten), the centromeres are then under a lot of tension and split. This divides each pair into individual chromosomes.46 pairs of sister chromatids = 46 individual chromosomes
    2 bunches of chromosomes

          

  4. meiosisMeiosis begins after a cell has progressed through interphase of the cell cycle - gametocyte
    Meiosis involves two successive divisions
    These are termed meiosis 1 and 2
    Each of these is subdivided into
    Prophase
    Prometaphase
    Metaphase
    Anaphase
    Telophase

    Prophase I is further subdividd into periods known as
    Leptotene
    Zygotene
    Pachytene
    Diplotene
    Diaknesis

    NO S PHASE - b/c you do not need another round of synthetic phase

          

  5. M phasemitosis

          

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