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  2. XY sex-determination system - Wikipedia

    en.wikipedia.org/wiki/XY_sex-determination_system

    The inverse of the XY system (called ZW to distinguish it) is used in birds and many insects, in which it is the females that are heterogametic (ZW), while males are homogametic (ZZ). [ 18 ] Many insects of the order Hymenoptera instead have a haplo-diploid system , where the females are full diploids (with all chromosomes appearing in pairs ...

  3. Sex-determination system - Wikipedia

    en.wikipedia.org/wiki/Sex-determination_system

    The XX/XY sex-determination system is the most familiar, as it is found in humans. The XX/XY system is found in most other mammals, as well as some insects. In this system, females have two of the same kind of sex chromosome (XX), while males have two distinct sex chromosomes (XY).

  4. Sex chromosome - Wikipedia

    en.wikipedia.org/wiki/Sex_chromosome

    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 chromosomes are called allosomes. These consist of two X chromosomes in females, and an X chromosome and a Y chromosome in males. Females ...

  5. Sex linkage - Wikipedia

    en.wikipedia.org/wiki/Sex_linkage

    In X-linked recessive inheritance, a son born to a carrier mother and an unaffected father has a 50% chance of being affected, while a daughter has a 50% chance of being a carrier, however a fraction of carriers may display a milder (or even full) form of the condition due to a phenomenon known as skewed X-inactivation, in which the normal ...

  6. Human genetics - Wikipedia

    en.wikipedia.org/wiki/Human_genetics

    The XY sex-determination system is the sex-determination system found in humans, most other mammals, some insects , and some plants . In this system, the sex of an individual is determined by a pair of sex chromosomes (gonosomes). Females have two of the same kind of sex chromosome (XX), and are called the homogametic sex.

  7. Sexual differentiation in humans - Wikipedia

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

    Differentiation between the sexes of the sex organs occurs throughout embryological, fetal and later life. In both males and females, the sex organs consist of two structures: the internal genitalia and the external genitalia. In males, the gonads are the testicles and in females, they are the ovaries.

  8. Zygosity - Wikipedia

    en.wikipedia.org/wiki/Zygosity

    The words homozygous, heterozygous, and hemizygous are used to describe the genotype of a diploid organism at a single locus on the DNA. Homozygous describes a genotype consisting of two identical alleles at a given locus, heterozygous describes a genotype consisting of two different alleles at a locus, hemizygous describes a genotype consisting of only a single copy of a particular gene in an ...

  9. X-linked recessive inheritance - Wikipedia

    en.wikipedia.org/wiki/X-linked_recessive_inheritance

    X-linked recessive inheritance. X-linked recessive inheritance is a mode of inheritance in which a mutation in a gene on the X chromosome causes the phenotype to be always expressed in males (who are necessarily hemizygous for the gene mutation because they have one X and one Y chromosome) and in females who are homozygous for the gene mutation, see zygosity.