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Unformatted text preview: -> C -> D). If there is a gain-of-function
mutation C* in gene C such that the protein is always active, that active phenotype would be seen even if it was
combined in a cell with a loss-of-function mutation in A
(A ). In this case, C is epistatic to A and must be after A in
the pathway. If the gain-of-function mutation is in A (A*) (b) Mutation in an Essential Gene
Diploid yeast cell Diploid yeast cell Mutagenize Mutagenize Mutation in one
gene (URA3) Mutation in DNA
URA3 URA3 URA3 Dead URA3 2 Ura : 2 Ura spores 2 live spores Figure A.7 Mutant isolation in a diploid cell. (a) A mutation on one homolog produces 2 and 2 spores if the mutation is
recessive and is in a non-essential gene. (Only one pair of homologous chromosomes is shown in the ﬁgure for simplicity.) (b) If the
mutation occurs in a gene that is essential for growth, only two live spores are recovered after meiosis. har06584_refA_001-020 11/4/06 10:09 AM Page 7 A....
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This note was uploaded on 10/03/2013 for the course BI 206 taught by Professor Celenza during the Spring '08 term at BU.
- Spring '08