You cross two yeast strains one is an ade auxotroph the other is a pro auxotroph and allowthe diploid to sporulate. When you score each spore in the ascus you find the followingproportions: 518 PD, 8 NPD, and 225 T.a.) What are the genotypes of each spore in all three types of the tetrads.b) Are these genes linked why or why not?c.) If these genes are unlinked what would you expect the progeny numbers and ratios tobe?d.) What is the formula to determine the most accurate distance between these genes? Iflinked what is the map distance?

Genes are the hereditary units that are transmitted from one generation to another generation. The…

diploid to sporulate. When you score each spore in the ascus you find the following portions: 518 PD, 8 NPD, and 225 T. What are the genotypes of each spore in all three types of the tetrads. Are these genes linked why or why not? If these genes are unlinked what would you expect the progeny numbers and ratios to

diploid to sporulate. When you score each spore in the ascus you find the following portions: 518 PD, 8 NPD, and 225 T. What are the genotypes of each spore in all three types of the tetrads. Are these genes linked why or why not? If these genes are unlinked what would you expect the progeny numbers and ratios to

Human Heredity: Principles and Issues (MindTap Course List)

11th Edition

ISBN:9781305251052

Author:Michael Cummings

Publisher:Michael Cummings

Chapter2: Cells And Cell Division

Section: Chapter Questions

Problem 20QP: In the following diagram, designate each daughter cell as diploid (2n) or haploid (n).

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JA yeast proline, histidine auxotroph is mated with a prototroph and the diploid cell is sporulated. a.) Write out the cross that generated the diploid cell? b. ) List the types of tetrads and the genotypes of each spore in the tetrad that will occur if this diploid cell is sporulated.
Indicate the percentage of tetrads that would have 0,1, 2, 3, or 4 viable spores after Saccharomycescerevisiae a / α diploids of the following genotypesare sporulated:a. A true-breeding wild-type strain (with no mutations in any gene essential for viability).b. A strain heterozygous for a null (completely inactivating) mutation in a single essential gene.For the remaining parts of this problem, considercrosses between yeast strains of the form a × b, wherea and b are both temperature-sensitive mutations indifferent essential genes. The cross is conducted under permissive (low-temperature) conditions. Indicatethe percentage of tetrads that would have 0, 1, 2, 3, or4 viable spores subsequently measured under restrictive (high-temperature) conditions.c. a and b are unlinked, and both are 0 m.u. from thecentromere.d. a and b are unlinked; a is 0 m.u. from the centromere, while b is 10 m.u. from the centromere.e. a and b are 0 m.u. apart.f. a and b are 10 m.u. apart. Assume all…
Imagine that you have done a cross between two strains of yeast, one of which has the genotype A B C and the other a b c, where the letters refer to three closely linked genes in the order given. You examine many tetrads resulting from this cross, and the two tetrads below are found that have atypical scoring patterns. In tetrad I, the spores are A B C, ABC, a B c, and a b c. In tetrad II, the spores are A B C, A b c, a b C, and a b c. Which tetrad or tetrads indicate(s) that gene conversion has occurred AND show(s) that recombination has occurred between genes A and C? O neither tetrads I and II O tetrad II O tetrad I O both tetrads I and II
A single yeast cell placed on a solid agar will dividemitotically to produce a colony of about 107cells. Ahaploid yeast cell that has a mutation in the ade2 genewill produce a red colony; an ade2+ colony will bewhite. Some of the colonies formed from diploidyeast cells with a genotype of ade2+/ ade2− willcontain sectors of red within a white colony.a. How would you explain these sectors?b. Although the white colonies are roughly the samesize, the red sectors within some of the whitecolonies vary markedly in size. Why? Do youexpect the majority of the red sectors to be relativelylarge or relatively small?
A heterozygous diploid yeast Aa Bb went through meiosis. What percentage of the haploid spores will have recombinant combinations of alleles? What if genes A and B are unlinked? Explain What is genes A and B are linked? Explain
The life cycle of the haploid fungus Ascobolus is similar tothat of Neurospora. A mutational treatment producedtwo mutant strains, 1 and 2, both of which when crossedwith wild type gave unordered tetrads, all of the followingtype (fawn is a light brown color; normally, crosses produce all black ascospores):spore pair 1 black spore pair 3 fawnspore pair 2 black spore pair 4 fawna. What does this result show? Explain.The two mutant strains were crossed. Most of the unordered tetrads were of the following type:spore pair 1 fawn spore pair 3 fawnspore pair 2 fawn spore pair 4 fawnb. What does this result suggest? Explain.When large numbers of unordered tetrads were screenedunder the microscope, some rare ones that containedblack spores were found. Four cases are shown here:Case A Case B Case C Case Dspore pair 1 black black black blackspore pair 2 black fawn black abortspore pair 3 fawn fawn abort fawnspore pair 4 fawn fawn abort fawn(Note: Ascospores with extra genetic material…
A cross was performed between a yeast strain that requires methionine and lysine for growth (met− lys−)and another yeast strain, which is met+ lys+. One hundred asci were dissected, and colonies were grownfrom the four spores in each ascus. Cells from thesecolonies were tested for their ability to grow on petriplates containing either minimal medium (min), min+ lysine (lys), min + methionine (met), or min + lys+ met. The asci could be divided into two groupsbased on this analysis:Group 1: In 89 asci, cells from two of the four spore colonies couldgrow on all four kinds of media, while the other two spore coloniescould grow only on min + lys + met.Group 2: In 11 asci, cells from one of the four spore colonies couldgrow on all four kinds of petri plates. Cells from a second one ofthe four spore colonies could grow only on min + lys plates andon min + lys + met plates. Cells from a third of the four sporecolonies could only grow on min + met plates and on min + lys+ met. Cells from the…
In a haploid yeast strain, eight recessive mutationswere found that resulted in a requirement for theamino acid lysine. All the mutations were found to revert at a frequency of about 1 × 10−6 except mutations5 and 6, which did not revert. Matings were madebetween a and α cells carrying these mutations. Theability of the resultant diploid strains to grow onminimal medium in the absence of lysine is shown inthe following chart (+ means growth and − means nogrowth.)1 2 3 4 5 6 7 81 − + + + + − + −2 + − + + + + + +3 + + − − − − − +4 + + − − − − − +5 + + − − − − − +6 − + − − − − − −7 + + − − − − − +8 − + + + + − + −a. How many complementation groups were revealedby these data? Which point mutations are foundwithin which complementation groups?The same diploid strains are now induced to undergosporulation. The vast majority of resultant spores areauxotrophic; that is, they cannot form colonies whenplated on minimal medium (without lysine). However,particular diploids can produce rare spores…
Neurospora of genotype a + c are crossed withNeurospora of genotype + b +. (Here, + is shorthandfor the wild-type allele.) The following tetrads areobtained (note that the genotype of the four sporepairs in an ascus are listed, rather than listing alleight spores):a + c a b c + + c + b c a b + a + ca + c a b c a + c a b c a b + a b c+ b + + + + + b + + + + + + c + + ++ b + + + + a b + a + + + + c + b +137 141 26 25 2 3a. In how many cells has meiosis occurred to yieldthese data?b. Give the best genetic map to explain these results.Indicate all relevant genetic distances, both betweengenes and between each gene and the centromere.c. Diagram a meiosis that could give rise to oneof the three tetrads in the class at the far right inthe list
For a haploid fungus, the starting point in the biosynthesis of the amino acid arginine is Compound X, which is always present in and absorbed from the environment. The arginine biosynthetic pathway is: Enzyme A Enzyme B Enzyme Ç Compound X It is know that genes encoding enzymes A and C are on two different chromosomes. Compound Y Compound Z- Arginine A mutant strain of genotype a (lacking only enzyme A) is crossed to a mutant strain of genotype c (lacking only enzyme C) to generate a diploid strain. Sporulation (i.e. meiosis) is subsequently induced in the resulting diploid strain. What proportion of the spores (haploids formed by sporulation) is expected to grow on medium without arginine but supplemented with Compound Y? O 100% 50% 0% 25%
From the fungal cross arg-6 ⋅ al-2 × arg-6+ ⋅ al-2+, whatwill the spore genotypes be in unordered tetrads thatare (a) parental ditypes? (b) tetratypes? (c) nonparental ditypes?
Match the following statement with the correct term.