Essential Genetics 6th Edition by Daniel Hartl

Exercise 13

Shown here is a primary RNA transcript with three exons (A, B, and C), which is alternatively processed in two ways to yield either an mRNA of sequence A-B or an mRNA of sequence B-C. An organism is mutant unless it has a functional product from both mRNAs. The black lines represent loss-of- function mutations in the exons.

(a) Draw the complementation matrix for the six mutations, using + to indicate complementation (wildtype phenotype) and - to represent lack of complementation (mutant phenotype).
(b) Explain what is unusual about this complementation matrix.