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  2. Ploidy - Wikipedia

    en.wikipedia.org/wiki/Ploidy

    Human diploid cells have 46 chromosomes (the somatic number, 2n) and human haploid gametes (egg and sperm) have 23 chromosomes (n). Retroviruses that contain two copies of their RNA genome in each viral particle are also said to be diploid.

  3. Spermatocyte - Wikipedia

    en.wikipedia.org/wiki/Spermatocyte

    Primary spermatocytes are diploid (2N) cells. After meiosis I, two secondary spermatocytes are formed. Secondary spermatocytes are haploid (N) cells that contain half the number of chromosomes. [1] In all animals, males produce spermatocytes, even hermaphrodites such as C. elegans, which exist as a male or hermaphrodite.

  4. List of organisms by chromosome count - Wikipedia

    en.wikipedia.org/wiki/List_of_organisms_by...

    Spider mites (family Tetranychidae) are typically haplodiploid (males are haploid, while females are diploid) [6] [6] 3 Cricotopus sylvestris: 4 [7] 4 Oikopleura dioica: 6 [8] 5 Yellow fever mosquito (Aedes aegypti) 6: The 2n=6 chromosome number is conserved in the entire family Culicidae, except in Chagasia bathana, which has 2n=8. [9] [9] 6 ...

  5. Polyploidy - Wikipedia

    en.wikipedia.org/wiki/Polyploidy

    This image shows haploid (single), diploid (double), triploid (triple), and tetraploid (quadruple) sets of chromosomes. Triploid and tetraploid chromosomes are examples of polyploidy. Polyploidy is a condition in which the cells of an organism have more than two paired sets of ( homologous ) chromosomes .

  6. Sexual reproduction - Wikipedia

    en.wikipedia.org/wiki/Sexual_reproduction

    In the first stage of sexual reproduction, meiosis, the number of chromosomes is reduced from a diploid number (2n) to a haploid number (n). During fertilisation, haploid gametes come together to form a diploid zygote, and the original number of chromosomes is restored.

  7. Alternation of generations - Wikipedia

    en.wikipedia.org/wiki/Alternation_of_generations

    Two single-celled haploid gametes, each containing n unpaired chromosomes, fuse to form a single-celled diploid zygote, which now contains n pairs of chromosomes, i.e. 2n chromosomes in total. [17] The single-celled diploid zygote germinates, dividing by the normal process , which maintains the number of chromosomes at 2n.

  8. Karyotype - Wikipedia

    en.wikipedia.org/wiki/Karyotype

    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. There may, or may not, be sex chromosomes. Polyploid cells have multiple copies of chromosomes and haploid cells have single copies.

  9. Meiosis - Wikipedia

    en.wikipedia.org/wiki/Meiosis

    Meiosis I segregates homologous chromosomes, which are joined as tetrads (2n, 4c), producing two haploid cells (n chromosomes, 23 in humans) which each contain chromatid pairs (1n, 2c). Because the ploidy is reduced from diploid to haploid, meiosis I is referred to as a reductional division.