Sex-linked inheritance regularly shows different phenotypic ratios in the two sexes of progeny, as well as different ratios in reciprocal crosses. In mammals, the presence of the Y determines maleness and the absence of a Y determines femaleness. Crossing the red-eyed F 1 males and females produces a F 2 ratio of red-eyed to white-eyed flies, but all the white-eyed flies are males.
If the father is affected, the son will not be affected, as he does not inherit the father's X chromosome, but the daughter will always be a carrier and may occasionally present with symptoms due to aforementioned skewed X-inactivation.
Males are said to be hemizygous, because they have only one allele for any X-linked characteristic. The O B allele causes the hairs to be black.
This single-gene-effect sex determination method is common in microorganisms. Genetic Information and Protein Synthesis Genes are expressed through the process of protein synthesis. So some of the gametes produced by males have an X, while others carry no sex chromosome at all. Genes that are located on the sex chromosomes follow slightly different rules to the genes located on the "regular" chromosomes, or autosomes.
Support Center Support Center. In humans, as well as in many other animals and some plants, the sex of the individual is determined by sex chromosomes. Namespaces Article Talk. If the mother is not a carrier, no male children of an affected father will be affected, as males only inherit their father's Y chromosome.
An Introduction to Genetic Analysis. Main article: X-linked dominant inheritance. Sex-influenced or sex-conditioned traits are phenotypes affected by whether they appear in a male or female body. Next Topic. They are also uniformly bronze because the E allele is completely dominant to the e allele and birds use a dosage compensation system similar to Drosophila and not mammals.