Unlike Mendel's experiments where the sex of the parent giving a trait didn't matter, here it does; sons look like their mothers. The same is true in humans, for whom pedigree analysis has revealed many X-linked genes, of which few could be construed as being connected to sexual function.
A well-studied sex-linked gene is the white gene on the X chromosome of Drosophila melanogaster. The process of identifying discuss sex determination and sex linkage in Reno phenotypes and then later determining which gene is involved is called forward genetics. The wild-type eye color of Drosophila is dull red, but pure lines with white eyes are available Figure However, for loci on the sex chromosomes this is mostly not true, because most of the loci on the typical X-chromosome are absent from the Y-chromosome, even though they act as a homologous pair during meiosis.
In mammals the dosage compensation system operates in females, not males.
Before we look at the consequences of chromosomally determined inheritance, let's put it in perspective by looking at other ways that sex is determined. And, this selective abortion doesn't happen only in plants. As expected, the results of the reciprocal crosses are the same, and are consistent with Mendel's predictions for independently assorting traits; the sex of the tongue-rolling parent doesn't matter - results in the reciprocal crosses are the same.
Sex Linkage Sex linkage describes the pattern of heredity between traits governed by genes on the sex chromosomes and the trait of 'sex', itself. If the ratio islike 2 X chromosomes in a normal diploid organism with two sets of autosomes, discuss sex determination and sex linkage in Reno the organism developes as a female.
This single gene can be lost from the chromosome through mutation, and sometimes it can even be transferred to the X during male sperm production.
At meiosis in females, the two X chromosomes pair and segregate like autosomes so that each egg receives one X chromosome. In flies, however, diploid organisms with only one X develop as males, even though they lack a Y. Explanation of the different results from reciprocal crosses between red-eyed red and white-eyed white Drosophila.
This means to cross a male and a female that have different phenotypes, and then conduct a second set of crosses, in which the phenotypes are reversed relative to the sex of the parents in the first cross. Actually, 'maleness' is determined by only a small region of the Y - called the "sex determining region of the y" - SRY - gene.
This only occurs in the couple sperm where this mutation occurred; it would not occur in all this man's sperm.