Episode 146: Mendelian Genetics and Inheritance

X-Linked Traits

X-linked traits exhibit unique inheritance patterns due to their location on the X chromosome. James Fodor explains that males, having only one X chromosome, are more likely to express recessive X-linked traits like color blindness and hemophilia. Females, with two X chromosomes, can be carriers without showing symptoms if they are heterozygous for the trait 1. This leads to a higher prevalence of these traits in males compared to females.

Males can't be carriers because they can't be heterozygous. This means that the X-linked recessive traits are much more common in males compared to females.

--- James Fodor

Additionally, skewed X inactivation can influence the expression of X-linked traits in females. This phenomenon occurs when one X chromosome is inactivated more frequently than the other, affecting the overall trait manifestation 2.

   

Chromosome Variation

The differences between X and Y chromosomes significantly impact genetic inheritance. James Fodor notes that males inherit an X chromosome from their mother and a Y chromosome from their father, while females inherit an X chromosome from each parent 3. This distinction leads to unique inheritance patterns for traits linked to these chromosomes.

Inheritance of traits that are encoded on either the X or the Y chromosome behaves differently to inheritance of traits that are encoded on all the other chromosomes.

--- James Fodor

The law of independent assortment further complicates inheritance patterns. This law states that genes on different chromosomes are inherited independently, but genes close together on the same chromosome may be inherited together due to crossing over 4.