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  2. XY sex-determination system - Wikipedia

    en.wikipedia.org/wiki/XY_sex-determination_system

    Non-human mammals use several genes on the Y chromosome. [citation needed] Not all male-specific genes are located on the Y chromosome. The platypus, a monotreme, use five pairs of different XY chromosomes with six groups of male-linked genes, AMH being the master switch. [8]

  3. Sex-determination system - Wikipedia

    en.wikipedia.org/wiki/Sex-determination_system

    The accepted hypothesis of XY and ZW sex chromosome evolution in amniotes is that they evolved at the same time, in two different branches. [84] [85] No genes are shared between the avian ZW and mammal XY chromosomes [26] and the chicken Z chromosome is similar to the human autosomal chromosome 9, rather than X or Y.

  4. Sex chromosome - Wikipedia

    en.wikipedia.org/wiki/Sex_chromosome

    Sex chromosomes (also referred to as allosomes, heterotypical chromosome, gonosomes, heterochromosomes, [1] [2] or idiochromosomes [1]) are chromosomes that carry the genes that determine the sex of an individual. The human sex chromosomes are a typical pair of mammal allosomes.

  5. Y chromosome - Wikipedia

    en.wikipedia.org/wiki/Y_chromosome

    The Y chromosome is one of two sex chromosomes in therian mammals and other organisms.Along with the X chromosome, it is part of the XY sex-determination system, in which the Y is the sex-determining chromosome because the presence of the Y chromosome causes offspring produced in sexual reproduction to be of male sex.

  6. Sexual differentiation in humans - Wikipedia

    en.wikipedia.org/wiki/Sexual_differentiation_in...

    Most mammals, including humans, have an XY sex-determination system: the Y chromosome carries factors responsible for triggering male development. In the absence of a Y chromosome, the fetus will undergo female development. This is because of the presence of the sex-determining region of the Y chromosome, also known as the SRY gene. [5]

  7. Locus (genetics) - Wikipedia

    en.wikipedia.org/wiki/Locus_(genetics)

    Each chromosome carries many genes, with each gene occupying a different position or locus; in humans, the total number of protein-coding genes in a complete haploid set of 23 chromosomes is estimated at 19,000–20,000. [2] Genes may possess multiple variants known as alleles, and an allele may also be said to reside at a particular locus.

  8. Males lose sex chromosome as they age. It could make ... - AOL

    www.aol.com/news/males-lose-sex-chromosome-age...

    The cells of those born male contain an X chromosome and a Y chromosome that make a pair and give instructions on which genes should be expressed in the body, the researchers said.

  9. Allele - Wikipedia

    en.wikipedia.org/wiki/Allele

    For a given locus, if the two chromosomes contain the same allele, they, and the organism, are homozygous with respect to that allele. If the alleles are different, they, and the organism, are heterozygous with respect to those alleles. Popular definitions of 'allele' typically refer only to different alleles within genes.