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  2. Genetic recombination - Wikipedia

    en.wikipedia.org/wiki/Genetic_recombination

    Most recombination occurs naturally and can be classified into two types: (1) interchromosomal recombination, occurring through independent assortment of alleles whose loci are on different but homologous chromosomes (random orientation of pairs of homologous chromosomes in meiosis I); & (2) intrachromosomal recombination, occurring through ...

  3. Sex chromosome anomalies - Wikipedia

    en.wikipedia.org/wiki/Sex_chromosome_anomalies

    Sex chromosome anomalies belong to a group of genetic conditions that are caused or affected by the loss, damage or addition of one or both sex chromosomes (also called gonosomes). In humans this may refer to: 45, X, also known as Turner syndrome; 45,X/46,XY mosaicism, also known as X0/XY mosaicism and mixed gonadal dysgenesis; 46, XX/XY

  4. List of genetic disorders - Wikipedia

    en.wikipedia.org/wiki/List_of_genetic_disorders

    The following is a list of genetic disorders and if known, type of mutation and for the chromosome involved. Although the parlance "disease-causing gene" is common, it is the occurrence of an abnormality in the parents that causes the impairment to develop within the child. There are over 6,000 known genetic disorders in humans.

  5. Sex chromosome - Wikipedia

    en.wikipedia.org/wiki/Sex_chromosome

    Human male XY chromosomes after G-banding. In humans, each cell nucleus contains 23 pairs of chromosomes, a total of 46 chromosomes. The first 22 pairs are called autosomes. Autosomes are homologous chromosomes i.e. chromosomes which contain the same genes (regions of DNA) in the same order along their chromosomal arms. The 23rd pair of ...

  6. Human genetic variation - Wikipedia

    en.wikipedia.org/wiki/Human_genetic_variation

    The human genome has a total length of approximately 3.2 billion base pairs (bp) in 46 chromosomes of DNA as well as slightly under 17,000 bp DNA in cellular mitochondria. In 2015, the typical difference between an individual's genome and the reference genome was estimated at 20 million base pairs (or 0.6% of the total). [2]

  7. Chromosomal rearrangement - Wikipedia

    en.wikipedia.org/wiki/Chromosomal_rearrangement

    It shows 22 homologous autosomal chromosome pairs, both the female (XX) and male (XY) versions of the two sex chromosomes, as well as the mitochondrial genome (at bottom left). In genetics, a chromosomal rearrangement is a mutation that is a type of chromosome abnormality involving a change in the structure of the native chromosome. [1]

  8. XXXY syndrome - Wikipedia

    en.wikipedia.org/wiki/XXXY_syndrome

    XXXY syndrome is a genetic condition characterized by a sex chromosome aneuploidy, where individuals have two extra X chromosomes. [2] People in most cases have two sex chromosomes: an X and a Y or two X chromosomes. The presence of one Y chromosome with a functioning SRY gene causes the expression of genes that determine maleness. Because of ...

  9. Polysomy - Wikipedia

    en.wikipedia.org/wiki/Polysomy

    Trisomy 21 – Down syndrome, an example of a polysomy at chromosome 21. Polysomy is a condition found in many species, including fungi, plants, insects, and mammals, in which an organism has at least one more chromosome than normal, i.e., there may be three or more copies of the chromosome rather than the expected two copies. [1]