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  2. Meiosis - Wikipedia

    en.wikipedia.org/wiki/Meiosis

    Overview of chromatides' and chromosomes' distribution within the mitotic and meiotic cycle of a male human cell. Meiosis occurs in all animals and plants. The result, the production of gametes with half the number of chromosomes as the parent cell, is the same, but the detailed process is different. In animals, meiosis produces gametes directly.

  3. Homologous chromosome - Wikipedia

    en.wikipedia.org/wiki/Homologous_chromosome

    Sorting of homologous chromosomes during meiosis. Meiosis is a round of two cell divisions that results in four haploid daughter cells that each contain half the number of chromosomes as the parent cell. [10] It reduces the chromosome number in a germ cell by half by first separating the homologous chromosomes in meiosis I and then the sister ...

  4. Nondisjunction - Wikipedia

    en.wikipedia.org/wiki/Nondisjunction

    In general, nondisjunction can occur in any form of cell division that involves ordered distribution of chromosomal material. Higher animals have three distinct forms of such cell divisions: Meiosis I and meiosis II are specialized forms of cell division occurring during generation of gametes (eggs and sperm) for sexual reproduction, mitosis is the form of cell division used by all other cells ...

  5. Chromosome - Wikipedia

    en.wikipedia.org/wiki/Chromosome

    Gametes are produced by meiosis of a diploid germline cell. During meiosis, the matching chromosomes of father and mother can exchange small parts of themselves , and thus create new chromosomes that are not inherited solely from either parent. When a male and a female gamete merge (fertilization), a new diploid organism is formed.

  6. Mitosis - Wikipedia

    en.wikipedia.org/wiki/Mitosis

    Mitosis in the animal cell cycle (phases ordered counter-clockwise). Mitosis divides the chromosomes in a cell nucleus. Onion cells in different phases of the cell cycle enlarged 800 diameters. Mitosis (/ maɪˈtoʊsɪs /) is a part of the cell cycle in which replicated chromosomes are separated into two new nuclei.

  7. Sexual reproduction - Wikipedia

    en.wikipedia.org/wiki/Sexual_reproduction

    Sexual reproduction is a type of reproduction that involves a complex life cycle in which a gamete (haploid reproductive cells, such as a sperm or egg cell) with a single set of chromosomes combines with another gamete to produce a zygote that develops into an organism composed of cells with two sets of chromosomes (diploid). [1]

  8. Parthenogenesis - Wikipedia

    en.wikipedia.org/wiki/Parthenogenesis

    Diploidy can be restored by the doubling of the chromosomes without cell division before meiosis begins or after meiosis is completed. This is an endomitotic cycle. Diploidy can also be restored by fusion of the first two blastomeres, or by fusion of the meiotic products. The chromosomes may not separate at one of the two anaphases ...

  9. Karyotype - Wikipedia

    en.wikipedia.org/wiki/Karyotype

    The basic number of chromosomes in the somatic cells of an individual or a species is called the somatic number and is designated 2n. In the germ-line (the sex cells) the chromosome number is n (humans: n = 23). [4] [5] p28 Thus, in humans 2n = 46. So, in normal diploid organisms, autosomal chromosomes are present in two copies.