Question

Describe what a conditional mutation is and why you would need to create one. Using the cdcX, cdcY, cdcZ example from your textbook, describe how complementation analysis was used to determine which cdc mutations were in the same or in different genes. Explain why this method would not work for dominant mutations.

Complementation analysis determines whether recessive mutations are in the same or different genes. Mutant (type a) (cdcx) Mutant (type c) (cacy) Mutant Mutant (type a) (type c) cdccdcz Mate haploids of opposite mating types and carrying different recessive temperature- sensitive cdc mutations cdcX/cdcY (type alo) cdcX/cdcz (type a/ac) Plate and incubate at permissive temperature Test resulting diploids for a temperature- sensitive cdc phenotype 23 °C 23°C Replica-plate and incubate at nonpermissive temperature 36°C Growth 36°C No growth PHENOTYPE: cdcx/ cdcy cdcx cdcz INTERPRETATION: Wild type Growth indicates that mutations cdcx and cdcy are in different genes Mutant Absence of growth indicates that mutations cdcx and cdcZ are in the same gene EX YBEL Respective wild-type alleles provide normal function Both alleles nonfunctional

Answer 1

Conditional mutation are those mutation which act as a wild type phenotype in normal conditions but act as mutant in restrictive condition. Conditional mutation act as a switch on and off point , which regulate expression of gene under the different conditions thus can be used to study function if a gene at a particular stage of developmental. For example we are studying role of A gene in early development of embryo, here gene A is regulated by temperature ( at 37 it will express normally at higher temperature its expression is shot down). So during embryo development if we increase the temperature than there will no no expression of this gene and we can easily study its effect on embryonic development.

Complementation testis done to detect weather mutation present in a two strains are on different chromosomes or on a similar chromosome.

If mutation are on different gene--- than complementation will occur --- normal phenotypes

If mutation present are on same gene ---- implementation will not occur --- generation of mutant phenotype.

This can be easily understand by taking the above mentioned example

(( de y mantent a Caley type if both mutation are in sane chremesine beth gefremutation are an defin gere - po during process of crossing over both wild gene cone in closure ansone so after crossing over reese allele both hosnators will remain at their sone place a chrenod one to temple sentare no sunive clue to both gene suure Cimplementation -