2019-04-02T15:55:42+03:00[Europe/Moscow] en true Prophase I, Metaphase I, Anaphase I, Telophase I, Prophase II, Metaphase II, Anaphase II, Telophase II, Homologous chromosomes, Crossing Over, Interphase, Replication, Haploid, Diploid, Sperm, Egg, Gamete, Meiosis, 46, somatic cells, XY, XX, 1n, 2n, Advantages of meiosis for sexual reproduction, germ cell flashcards
Meiosis

Meiosis

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  • Prophase I
    Each chromosome comes near its replicated chromosome pair. Nucleus dissolves at this stage. Crossing Over (exchange of genetic material) occurs at this phase.
  • Metaphase I
    The pairs of homologous chromosomes line up in the center of the cell. The centromere of each chromatid pair attaches to one spindle fibre.
  • Anaphase I
    Homologous chromosomes are pulled to opposite ends of the cell. Note that chromatids do not separate - each duplicated chromosome still has two chromatids.
  • Telophase I
    The cytoplasm divides and two new cells form. Each new cell has one duplicated chromosome from each similar pair.
  • Prophase II
    The duplicated chromosomes and spindle fibers reappear in each new cell.
  • Metaphase II
    The duplicated chromosomes move to the centre of the cell. Each centromere attaches to two spindle fibres instead of one.
  • Anaphase II
    The centromere divides. The chromatids seperate and move to opposite ends of the cell. Each chromatid is now an individual chromosome.
  • Telophase II
    The spindle fibres disappear, and a nuclear membrane forms around each set of chromosomes.
  • Homologous chromosomes
    Chromosomes that have the same sequence of genes, that have the same structure, and that pair during meiosis.
  • Crossing Over
    Process in which homologous chromosomes exchange portions of their chromatids during meiosis. This increases genetic variation.
  • Interphase
    Chromosomes replicate in preparation for meiosis. At this point they are long and thin and called "chromatin".
  • Replication
    Chromosomes duplicate before dividing in meiosis.
  • Haploid
    A cell that contains only one set of chromosomes instead of the normal pair. Gametes, which are sex cells like sperm and eggs, are haploid cells.
  • Diploid
    A cell that contains two sets of chromosomes; one inherited from the mother and one inherited from the father. Most body cells (nerve, brain, muscle, skin, etc.) are considered diploid cell.
  • Sperm
    Male gamete (sex cell)
  • Egg
    Female gamete (sex cell)
  • Gamete
    The result of meiosis is 4 gametes, aka sex cells, that each contain half of the genetic information in the parent organism.
  • Meiosis
    A process in cell division during which the number of chromosomes decreases to half the original number. It occurs by two divisions of the nucleus and results in the production of 4 sex cells (gametes).
  • 46
    number of chromosomes present in humans
  • somatic cells
    body cells, they are also diploid aka contain both sets of chromosomes
  • XY
    the genetic coding for a male
  • XX
    the genetic coding for a female
  • 1n
    symbol for haploid cells such as reproductive cells
  • 2n
    symbol for diploid cells such as body cells
  • Advantages of meiosis for sexual reproduction
    more genetic diversity or genetic variation in reproductive cells and thus in offspring which generally leads to an increased chance of survival
  • germ cell
    undifferentiated or unspecialized cell that can become haploid gametes (egg and sperm) when it divides in meiosis