Sex Linkage and Epistasis
This page delves into more advanced genetic concepts, focusing on sex linkage and epistasis explained with punnet squares. It begins with an explanation of sex-linked inheritance, using color blindness as an example.
Example: In a cross between a carrier female (XᴿXʳ) and a healthy male (XᴿY), there is a 25% chance of having a color-blind male offspring.
The page illustrates different scenarios of sex-linked inheritance, including a color-blind male crossed with a healthy female, demonstrating how the trait is passed differently to male and female offspring.
Highlight: In a cross between a color-blind male and a healthy female, all female offspring will be carriers, while all male offspring will be healthy.
The concept of epistasis is then introduced, using coat color in horses as an example. This demonstrates how one gene can mask or modify the expression of another gene.
Definition: Epistasis occurs when the expression of one gene is affected by the presence or absence of one or more other genes.
A detailed punnet square is provided to show the inheritance of two interacting genes: one controlling pigment production (B for black, b for brown) and another controlling an enzyme that degrades pigment (E for enzyme present, e for enzyme absent).
Example: A horse with the genotype BBEE will be white, despite having the genes for black coat color, because the E gene produces an enzyme that degrades all pigment.
The page concludes with a complex punnet square demonstrating the F2 generation of this epistatic interaction, showing the various possible genotypes and their corresponding phenotypes.
Vocabulary: Autosomal linkage refers to the inheritance of genes located on non-sex chromosomes, which can lead to more complex inheritance patterns than those seen with single-gene traits.
This comprehensive guide provides a thorough understanding of advanced genetic concepts, using clear examples and punnet squares to illustrate complex inheritance patterns.
![Punnet Squares
B-Brown eyes b - Blue eyes (monohybrid inheritance)
Homozygous dominant + Homozygous recessive
BB
F1 Cross
B B
Bb
D Bb
b] Bb](/_next/image?url=https%3A%2F%2Fcontent-eu-central-1.knowunity.com%2FCONTENT%2FaJEwXQAeNAnrBqeBexRu_image_page_2.webp&w=828&q=75)
![Punnet Squares
B-Brown eyes b - Blue eyes (monohybrid inheritance)
Homozygous dominant + Homozygous recessive
BB
F1 Cross
B B
Bb
D Bb
b] Bb](/_next/image?url=https%3A%2F%2Fcontent-eu-central-1.knowunity.com%2FCONTENT%2FaJEwXQAeNAnrBqeBexRu_image_page_1.webp&w=2048&q=75)
![Punnet Squares
B-Brown eyes b - Blue eyes (monohybrid inheritance)
Homozygous dominant + Homozygous recessive
BB
F1 Cross
B B
Bb
D Bb
b] Bb](/_next/image?url=https%3A%2F%2Fcontent-eu-central-1.knowunity.com%2FCONTENT%2FaJEwXQAeNAnrBqeBexRu_image_page_2.webp&w=2048&q=75)