Dosage compensation: an intertwined world of RNA and chromatin remodelling. C-banding of L. Inherited genetic defects play an important role in congenital hearing loss, contributing to about 60 percent of deafness occurring in infants. In addition, if polyandry may evolve through sexual selection in females, sperm competition theory predicts that males should benefit from a reduction in female mating rate to increase their mating success Parker Relative DNA content of normal and sex-ratio distorting spermatozoa of the mosquito, Aedes aegypti L.
It was revealed by interspecific crosses that lifted the suppression.
At meiosis the X and Y chromosomes first pair then disjoin and pass to different cells. This is because the male who inherits the recessive allele on his X chromosome has no allele on his Y chromosome to counteract its effects. A non-fertilized egg may develop into a male.
Sperm cells carry either an X or Y sex chromosome. Info Print Print. Female gametes, or eggs, however, contain only the X sex chromosome and are homogametic.
Grasshoppers, roaches, and other insects have a similar system for determining the sex of an individual. In this case, the DNA of the unaffected father is passed down. The effects of genes carried only on the Y chromosome are, of course, expressed only in males.
Articles from Britannica Encyclopedias for elementary and high school students. At meiosis the X and Y chromosomes first pair then disjoin and pass to different cells. If the sperm cell contains a Y chromosome, then the resulting zygote will be XY, or male.
Moreover, the interaction between the heterochromatin and the proteins involved in its regulation is one of the key steps that led to the centromere drive hypothesis, as argued by Malik and Henikoff Both traits localize to a DNA fragment of 80 kb or smaller and may be pleiotropic effects from a single gene.
Such genes were not further investigated. The most conserved region of D. Does polyandry control population sex ratio via regulation of a selfish gene?