Question

KHomework II Practice Problem 115 Review Three haploid yeast petite mutants were isolated one from each of the three classes of petite mutations-suppressive petites, neutral petites, and segregational petites. You perform the crosses shown in this table. Progeny (haploid spores) Cross 50% petite: 50% wild petite #1 x wild type type petite #2 x wild type 100% petite P petite #3 x wild type 100% wild type Se on WoL mini ferm Whic coul mutant ( will segregate in a 2:2 ratio. Since neutral petites lack mitochondrial DNA, all of the mitochondria in the offspring will come from the segregational petite parent. Thus, half of the offspring will be wild type and half will be mutant. Part C Several isolated haploid petite mutants and wild-type cells were mated with each other on complete media to form diploid cells. The diploid cells were then starved so they would go through meiosis and form haploid spores. The spores were grown on minimal media plates that contained glycerol as the only carbon source (so no fermentation could occur) Which of the following crosses would be able to produce haploid spores that could grow on the minimal media plus glycerol plates? Select all that apply. segregational petite x wild type segregational petite x neutral petite segregational pette x suppressive petite suppressive petite x wild type suppressive petite x neutral petite neutral petite x wild type Previous Answers Request Answer Submit X Incorrect; Try Again; 3 attempts remaining Provide Feedback Next> bp m

Answer 1

Petites contains a mutation which cause cytochrome deficiency or deficiency of enzyme involved in respiration. Due to this petites are unable to grow on medium containing only non-fermentable carbon source. Petites may of three type -

Segregational - contain mutation in nuclear gene and shows normal Mendelian inheritance and when crossed with wild type form half normal and half petite with defective mitochondria.

Normal petite - shows cytoplasmic inheritence and when crossed with wild type, all wild type with normal mitochondria are formed.

Suppressive petite contain mutation of suppressive type and causes suppression of normal. Mitochondria hence when crossed with wild type gives all petite cells.

Hence the cross between

Segregational petite ×wild type will form half Grande(Normal that can survive on non-fermentable carbon source).

And also offspring of Normal petite crossed with wild type shows all cell of Grande type. Only option 1st and last are correct.