Question

A cross was performed between a yeast strain that requires histidine and methionine for growth (His-Met-) and another yeast strain, which is His+Met+. One hundred asci were dissected, and colonies were grown from the four spores in each ascus. Cells from these colonies were tested for their ability to grow on petri plates containing either minimal medium(min), min+histidine (his), min+methionine (met),or min+his+met. The number of tetrads with four spores that can grow in different type of media is shown in the table below: Classes of tetrads I II III min min+met min The media in which each of min+met min+his min the four spores from the min+his min+met min+his+met tetrad can grow min+his+met min+his min+his+met Numbers 40 55 5 a) Which class of the tetrad in the table is the NPD? Class I O Class II O Class III Submit Answer Tries 0/99 b) Are the his and met genes linked? Briefly explain why you think so. Submission type: O Submit entries below as answer to receive credit Save entries below (not submitted for credit yet) Rich formatting » Submit Answer Tries 0/99

Answer 1

Q1 Class ll tetrads. Spores than grow in min+met must be met- his+ , which is a recombinant and spores than grow in min+his must be met+ his- . Which show that the class two tetrads is composed of spores that are not parental types.

The genes are linked since the number of recombinants is very low. Linked genes give very lowlow number of recombinants since they are inherited together. Recombinant class contains only 5 members, compared to 55 of the parental type class. There for the number of recombinants are less than 50% which implies that the genes are linked