Question

How does one recognize sex-linked inheritance? How could one distinguish a sex-linked dominant allele from a sex-linked recessive allele?

What is the significance of a recombination frequency of 50%? Is it possible to have a recombination rate significantly greater than 50% (such as 80 or 90%)?

Answer 1

ANSWER 1 Sex linked inheritance is of three types X linked recessive, X linked dominant and Y linked.In mammals, the female is homogametic, with two X chromosomes (XX), while the male is the heterogametic sex, with one X and one Y chromosome (XY). In X linked recessive inheritance all heterogametetic sex will be affected. All female children of an affected father will be carriers of the disease. X linked dominant, Each child of a mother affected with an X-linked dominant trait has a 50% chance of inheriting the mutation and thus being affected with the disorder. If only the father is affected, 100% of the daughters will be affected, since they inherit their father's X-chromosome. Y linked inheritance all males are affected no female get affected.

ANSWER 2 The recombination frequency between two genes is equal to the proportion of offspring in which a recombination event occurred between the two genes during meiosis. The recombination frequency between two genes cannot be greater than 50% because random assortment of genes generates 50% recombination (non-linked genes produce 1:1 parental to non-parental. Thus, the recombination frequency would be non-parental/total Æ1/(1+1) = 50%).