A sex linked disorder in male is represented by a geometrical figure of filled square. A sex-linked disorder is a disease which is linked to one of the chromosome (X or Y) that is passed on to the daughter and son. The majority of individuals affected are males. The affected males never pass on the disease to his son because there is no transmission of X chromosome from him. They pass their affected X chromosome to the female that becomes carrier of the disease. As men only get one X chromosome there is no chance of that chromosome to be recessive because there is no dominant X chromosome. So, males can never be the carrier of sex linked disorder They can only be affected by the disorder.
Filled square is used to label a male that expresses a sex-linked disorder on a pedigree.
Further Explanation:
A pedigree chart depicts the expression of phenotypic traits in the ancestors and the descendants of different generations.In the diagrammatic representation, the circle represents the female and the square represents a male. If the entire shape is shaded or colored, it means that the person is affected. In the parental generation, a single female mate with two males, to give birth to the boy child in the first generation.Sex of the descendant is always dependent upon the sperm cell containing the Y chromosome.If the egg cell containing a single X chromosome fertilizes with a sperm containing the Y chromosome, it will result in males. And, if it binds a sperm containing the X chromosome, it will result in a female.Generally, the genetic cross between a male and a female has a 50% outcome of either of the two genders in the offspring.
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Answer Details:
Grade: High School
Subject: Biology
Topic: Pedigree Analysis
Keywords:
Pedigree, expression, phenotypic traits, ancestor, descendants, body, males, females, circle, square, sex, offspring, single, chromosome.
