8.3 Study Guide

Question 1

Important similarities and differences between different modes of inheritance: autosomal dominant, autosomal recessive, sex-linked recessive, sex-linked dominant

Answer 1

Similarities: They are modes of inheritance.
Differences: Two are dominant two are recessive. Two are autosomal two are sex-linked. Autosomal apply to autosomes and sex-linked apply to sex chromosomes.

Question 2

Example of a sex-linked cross?

Answer 2

XRXr x XRY.

Question 3

How to rule out different modes of inheritance on a pedigree and assign genotypes to individuals on a pedigree.

Answer 3

If it is evenly spread between males and females and one of the starting parents has it, then it is autosomal dominant. If it is evenly spread between males and females and one of the starting parents is a carrier with it, then it is autosomal recessive. If it is not evenly spread between males and females and one of the starting parents has it, then it is sex-linked dominant. If it is not evenly spread between males and females and one of the starting parents is a carrier with it, then it is sex-linked recessive. You can assign A_ to anything afflicted with a dominant, or aa to anything afflicted with recessive, and anything that doesn’t will be the opposite.