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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 ...
The symbol of the Roman goddess Venus is used to represent the female sex in biology. [1] An organism's sex is female (symbol: ♀) if it produces the ovum (egg cell), the type of gamete (sex cell) that fuses with the male gamete (sperm cell) during sexual reproduction. [2] [3] [4] A female has larger gametes than a male.
In the XY sex-determination system, the female-provided ovum contributes an X chromosome and the male-provided sperm contributes either an X chromosome or a Y chromosome, resulting in female (XX) or male (XY) offspring, respectively. Hormone levels in the male parent affect the sex ratio of sperm in humans. [25]
Females that are heterozygous for X-linked recessive disorders are obligate carriers, but can never be phenotypically affected, and this is because of X-inactivation. Heterozygous females have an X-chromosome from each parent; one with a mutated gene and one with a functional copy of the same gene.
If the alleles are different, the genotype is referred to as heterozygous. Genotype contributes to phenotype, the observable traits and characteristics in an individual or organism. [3] The degree to which genotype affects phenotype depends on the trait. For example, the petal color in a pea plant is exclusively determined by genotype.
Fertilized eggs develop into diploid individuals which, due to high variability in the csd locus, are generally heterozygous females. In rare instances, diploid individuals may be homozygous, these develop into sterile males.
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.
When in the F1 offspring of two different animal races one sex is absent, rare, or sterile, that sex is the heterozygous sex (heterogametic sex). [3] Haldane's rule applies to the vast majority of species that have heterogametic chromosomal sex determination (e.g. XX females vs. XY males, or ZW females vs. ZZ males).