Independent Assortment is the second law of inheritance
Traits are passed from parents to offspring independently of one another.
Independent assortment is random and occurs during Metaphase I of meiosis. There are two possible alignments for the chromosomes. Since the alignments are random and not assigned, genetic variation occurs.
Independent grouping of qualities happens amid meiosis in eukaryotes. Meiosis could be a sort of cell division that diminishes the number of chromosomes in a parent cell by half to deliver four regenerative cells called gametes. In people, diploid cells contain 46 chromosomes, with 23 chromosomes acquired from the mother and a moment comparative set of 23 chromosomes acquired from the father. Sets of comparable chromosomes are called homologous chromosomes. Amid meiosis, the sets of homologous chromosome are separated in half to make haploid cells, and this partition, or grouping, of homologous chromosomes is arbitrary. This implies that all of the maternal chromosomes will not be isolated into one cell, whereas the all fatherly chromosomes are isolated into another. Instep, after meiosis happens, each haploid cell contains a blend of qualities from the organism's mother and father.
This disorder is caused by a recessive allele, its inheritance is sex-linked.
Explanation:
The disorder affects boys born to unaffected parents, this means that at least one of them has to be a carrier of the allele which causes the disease. So, if the allele was dominant, it would express in parents and sons. But, in this case, only is expressed in sons, so it can´t be dominant. Moreover, this condition has a sex-linked inheritance because it is always seen in boys and never in girls. This happens due to boys only have an X chromosome, so if they inherit the recessive allele of the disease, they will express it. On the other hand, girls have two X chromosomes, so if they inherit one copy of the recessive allele, they will be carriers and they won't be affected.
This disorder is never seen in females because they need to have two copies of the recessive allele. However, to have double copy, they should inherit one copy from their mothers and one copy of their fathers, but boys with the allele are affected and they die in early teens without having progeny. Therefore, a girl can't have a "carrier-father", so they will never have two copies to express the disorder.
People who have darker skin have more melanin which is a black or dark brown pigment in the skin. When we are out in the sun our skin produces more melanin, which helps our skin be more resistant in the sun. This is why we tan.
