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Unformatted text preview: If the pathway being dissected genetically contains
genes that are essential for cell viability, the isolation of
mutants in a diploid becomes essential. For example, a
diploid containing a mutation in a DNA replication gene
yields two live spores and two dead spores after sporulation
(Fig. A.7b). A lethal phenotype informs us that there is a
mutation in an essential gene in the diploid, but it is not
useful for further studies. To study an essential gene, it is
more useful to isolate conditional mutants that express the
mutant phenotype under restrictive conditions but not at
permissive temperatures. Temperature-sensitive and coldsensitive mutations are examples of conditional mutations.
Yeast is ideal for isolating this type of mutation because it (a) Mutation in Non-essential Gene grows at temperatures from 15°C to 37°C. A screen for
conditional mutants was the starting point for isolation of
cell division cycle mutations (cdc) that led to an understanding of cancer biology (see Chapter 19 of the main textbook...
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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