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  2. Sex-determination system - Wikipedia

    en.wikipedia.org/wiki/Sex-determination_system

    For example, in some species of cichlid fish from Lake Malawi, if an individual has both the XY locus (on one chromosome pair) and the WZ locus (on another chromosome pair), then the W is dominant and the individual has a female phenotype. [40] The sex-determination system of zebrafish is polygenic. Juvenile zebrafishes (0–30 days after ...

  3. Haplodiploidy - Wikipedia

    en.wikipedia.org/wiki/Haplodiploidy

    According to this model, if an individual is heterozygous for a certain locus, it develops into a female, whereas hemizygous and homozygous individuals develop into males. In other words, diploid offspring develop from fertilized eggs, and are normally female, while haploid offspring develop into males from unfertilized eggs.

  4. XY sex-determination system - Wikipedia

    en.wikipedia.org/wiki/XY_sex-determination_system

    In this system, the sex of an individual usually is determined by a pair of sex chromosomes. Typically, females have two of the same kind of sex chromosome (XX), and are called the homogametic sex. Males typically have two different kinds of sex chromosomes (XY), and are called the heterogametic sex. [1]

  5. Sex differences in human physiology - Wikipedia

    en.wikipedia.org/wiki/Sex_differences_in_human...

    Sperm also have only one set of 23 chromosomes and are therefore haploid. When an egg and sperm fuse at fertilization, the two sets of chromosomes come together to form a unique diploid individual with 46 chromosomes. [2] The sex chromosome in a human egg is always an X chromosome since a female only has X sex chromosomes.

  6. 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 ...

  7. Sex chromosome - Wikipedia

    en.wikipedia.org/wiki/Sex_chromosome

    In contrast, a female must inherit two mutant alleles, a less frequent event since the mutant allele is rare in the population. X-linked traits are maternally inherited from carrier mothers or from an affected father. Each son born to a carrier mother has a 50% probability of inheriting the X chromosome carrying the mutant allele.

  8. Reproductive isolation - Wikipedia

    en.wikipedia.org/wiki/Reproductive_isolation

    But there are also organisms in which the heterozygous sex is the female: birds and butterflies and the law is followed in these organisms. Therefore, it is not a problem related to sexual development, nor with the sex chromosomes.

  9. Test cross - Wikipedia

    en.wikipedia.org/wiki/Test_cross

    Under the law of dominance in genetics, an individual expressing a dominant phenotype could contain either two copies of the dominant allele (homozygous dominant) or one copy of each dominant and recessive allele (heterozygous dominant). [1] By performing a test cross, one can determine whether the individual is heterozygous or homozygous ...