Re: Recessive mutations

Recessive mutations are more easily detectable in bacteria mainly because 
they are haploid organisms.  This means that they only have one "set" of 
genes.  Diploid organisms (like humans) have two sets of genes.  One is from 
the mother and one from the father.  Therefore, in diploid organisms the 
recessive mutation may be masked by a dominant gene.  Yeasts can have a 
diploid phase when they reproduce sexually.  But often they grow asexually. 

Another factor to consider when looking at yeast and bacteria is that it 
is much easier to manipulate their environmental conditions in a laboratory 
setting.  So, if you are looking for a recessive mutation that causes 
lactose (just an example) metabolism to not work, you can try growing these 
organisms in a media that contains only lactose as an energy source.  The 
ones that will not grow have the mutation.