This preview shows page 1. Sign up to view the full content.
Unformatted text preview: Neurospora is an ideal model system for studying allelic segregation at meiosis. (a) The four products of meiosis (tetrad) undergo mitosis to produce an octad. The products are contained within an ascus. (b) An A / a meiocyte undergoes meiosis, then mitosis, resulting in equal numbers of A and a products, demonstrating the principle of equal segregation. al 1 represents the wild-type allele coding for pigment production, and al the albino-causing allele: Pink wild type albino al 1 3 al In the haploid sexual cycle, we have seen that haploid parental cells of each type fuse to form transient diploid meiocytes, each one of which produces an eight-spore ascus. Every ascus from the above cross will have four pink ( al 1 ) and four white ( al ) ascospores, directly demonstrating the Mendelian law of equal segregation at the level of a single meiocyte (Figure 3-37b). 44200_03_p73-114 3/3/04 1:48 PM Page 101...
View Full Document
This note was uploaded on 01/10/2011 for the course BIOL BIOL taught by Professor Johnson during the Spring '08 term at Aberystwyth University.
- Spring '08