The a, b, and c loci are all on different chromosomesin yeast. When a b+ yeast were crossed to a+ b yeastand the resultant tetrads analyzed, it was found thatthe number of nonparental ditype tetrads was equal tothe number of parental ditypes, but there were no tetratype asci at all. On the other hand, many tetratypeasci were seen in the tetrads formed after a c+ wascrossed with a+ c, and after b c+ was crossed withb+ c. Explain these results.
Q: Mitotic recombination can occasionally produce a twin spot.Let’s suppose an animal species is…
A: It is given to suppose that if an animal species is heterozygous for the 2 gene governing fur colour…
Q: While conducting field studies on a chain of islands, you decide tokaryotype two phenotypically…
A: When individuals of the same specie are geographically isolated, it may happen that the population…
Q: The alleles his-5 and lys-1, found in baker’s yeast, result in cellsthat require histidine and…
A: The first step is to determine which asci are parental ditypes (PD), non-parental ditypes (NPD) and…
Q: f the G locus were 50 or more map units from the centromere, what types and proportions of gametes…
A: Recombination in terms of genetics describe the process that explain the exchange of genetic…
Q: A single yeast cell placed on a solid agar will dividemitotically to produce a colony of about…
A: Cell division is a natural process in which a parent cell divides into two daughter cells. Cell…
Q: In the haploid yeast Saccharomyces cerevisiae, the twomating types are known as MATa and MATα. You…
A: Saccharomyces cerevisiae refers to a species of yeast used in brewing, baking, and winemaking…
Q: A heterozygous diploid yeast Aa Bb went through meiosis. What percentage of the haploid spores will…
A: Recombination is defined as the process or method by which the DNA pieces are broken down and are…
Q: On a camping trip, you find one male snail on a desertedisland that coils to the right. However, in…
A: Introduction The life starts from single cell called Zygote. A zygote is formed by the fusion of…
Q: Two diploid species of closely related frogs, which we will callspecies A and species B, were…
A: Evolution is defined as inheritable changes over multiple generations of a population of organisms.…
Q: Why should the relative distance between two loci influencethe amount of recombination and crossing…
A: Chromosomal hybrid, or crossover, is the exchange of genetic material during sexual multiplication…
Q: . Imagine that you have done a cross between twostrains of yeast, one of which has the genotype A B…
A: A genetic cross is defined as deliberately mating two individuals to create a desired genotype in…
Q: In maize trisomics, n + 1 pollen is not viable. If adominant allele at the B locus produces purple…
A: The trisomic condition is condition in which the normal diploid species has one additional…
Q: Female flies with white eyes and miniature wings (both X-linkedrecessive traits) were crossed to…
A: Chromosomal composition of these rare females will be – XXY. Both the X chromosomes must be coming…
Q: . An allotetraploid species has a genome composed oftwo ancestral genomes, A and B, each of which…
A: An allotetraploid is a condition in which a hybrid contains chromosomes 4 times that of a haploid…
Q: In Neurospora, his2 mutants require the amino acidhistidine for growth, and lys4 mutants require…
A: Neurospora is a type of a fungus that has axon like striations on its spores. The spores of the…
Q: Map distances were determined for four differentgenes (MAT, HIS4, THR4, and LEU2) on chromosome III…
A: Chromosomes are long thread like structures that carry coded genetic information in the form of…
Q: . The numbers of chromosomes in the somatic cells ofseveral oat varieties (Avena species) are: sand…
A: Polyploid organisms contain more than two complete sets of chromosomes, x is the basic chromosome…
Q: This problem leads you through the derivation of acorrected equation for RF in yeast tetrad analysis…
A: Since you have posted a question with multiple sub-parts, we will solve first three sub-parts for…
Q: Two heterozygous parents are crossed. If the two loci are linked whatwould be the distribution of…
A: Genetics is a branch of biology that deals with genes, heredity, and variation. Heredity purely…
Q: . In ordered tetrad analysis, what is the maximumRF that you could observe between a gene and…
A: RF means the recombinant frequency is a measure of the distance separating the two genes along a…
Q: A crossover has occurred in the bivalent shown in figure.What is the outcome of this single…
A: Genetics is the branch of biology which deals with genes, heredity, and genome in the organism.…
Q: In Drosophila, males from a true-breeding stock withraspberry-colored eyes were mated to females…
A: Recombination frequency (RF) is the rate of occurrence of recombination between a pair of linked…
Q: why The chromatids formedby recombination within the inversion loop of a paracentric…
A: When the region between two breaks of the same chromosome rotates 180°, it results in chromosomal…
Q: In a haploid fungus, the genes al-2 and arg-6 are 30 m.u.apart on chromosome 1, and the genes lys-5…
A: Chromosomes These are the densely packed DNA structures with proteins.Multiple genes can be found on…
Q: In a human genetic study, a family with five phenotypicallynormal children was investigated. Two…
A: Introduction: The compact form of DNA is known as chromosomes.
Q: The recessive, X-linked z1mutation of the Drosophilagene zeste (z) can produce a yellow (zeste) eye…
A: Gene is the specific sequence of nucleotide in deoxyribonucleic acid (DNA) or ribonucleic acid (RNA)…
Q: From the fungal cross arg-6 ⋅ al-2 × arg-6+ ⋅ al-2+, whatwill the spore genotypes be in unordered…
A: Introduction: Inheritance is a term used to describe the process by which a parent's traits are…
Q: The life cycle of the haploid fungus Ascobolus is similar tothat of Neurospora. A mutational…
A: Ascobolus is the fungal genus and consists of around 48 species. It is considered to be a…
Q: why The chromatids formedby recombination within the inversion loop of a paracentric…
A: When the region between two breaks of the same chromosome rotate 180°, it results in chromosomal…
Q: On Neurospora chromosome 4, the leu3 gene is just to theleft of the centromere and always segregates…
A: Introduction: During the zygotene phase, a structure known as the synaptonemal complex forms between…
Q: Drosophila P elements were discovered because ofa phenomenon called hybrid dysgenesis—sterilityof…
A: The P element in the Drosophila is the transposon genes. The transposons or transposable elements…
Q: mosome constitution. When the seed parent was O. hookeri, the plastids of the progeny were yellow;…
A: There are certain traits that are not inherited by conventional means of nuclear information. It is…
Q: In autotetraploid Chinese primrose (Primula sinensis L.), the gene controlling stigma color is very…
A: Autotetraploid: It consists of four copies of an individual genome. It consists of the doubling of…
Q: Incomplete dominance and epistasis are both terms thatdefine genetic relationships. What is the most…
A: Genes come in pairs and are responsible for the inheritance and expression of the associated…
Q: During ascus formation in Neurospora, any ascosporewith a chromosomal deletion dies and appears…
A: Since you have posted a question with multiple sub-parts, we will solve first three sub-parts for…
Q: In Drosophila, a cross (cross 1) was made between twomutant flies, one homozygous for the recessive…
A: Homozygous organisms are those that have two identical alleles. These can either be dominant or…
Q: The alleles his-5 and lys-1, found in baker’s yeast, result in cellsthat require histidine and…
A: The alleles of beaker yeasts his-5 and lys-1 results in the cells that require histidine and lysine.…
Q: Let’s say there is an organism with two pairs of alleles, W/w and Z/z, each pair is located on a…
A: Cell division is a phenomenon takes place inside the cell during which parent cell undergo…
Q: . In a particular kind of ornamental flower, the wildtype flower color is deep purple, and the…
A: Inheritance is the process of transmitting the traits from parent to offspring. Traits of an…
Q: The normal sequence of nine genes on a certainDrosophila chromosome is 123 • 456789, where the…
A: The basic karyotype of Drosophila melanogaster, which is observed mitotically comprises active…
Q: Indicate the percentage of tetrads that would have 0,1, 2, 3, or 4 viable spores after…
A: Hi there! Since you have posted multiple questions, we are answering only first two sub-parts. In…
Q: In a cross in Drosophila, a female heterozygous for the autosomallylinked genes a, b, c, d, and e…
A: Homozygous refers to the genotype of an organism with two identical alleles at a locus. Heterozygous…
Q: "The genotype of the organism producing the crossovergametes must be heterozygous at all loci…
A: The position of a gene on a chromosome is referred to as loci (plural locus). The location of a gene…
Q: The human genome consists of 23 pairs of chro-mosomes (22 pairs of autosomes and one pair of sex…
A: Cell division occurs in sexually reproducing bodies in which we get four daughter cells produced…
Q: Two crosses were made in Neurospora involvingthe mating type locus and either the ad or p genes.In…
A: A locus may be defined as the position of a gene on a chromosome. The loci help in gene mapping of…
Q: The drug ivacaftor has recently been developed totreat cystic fibrosis in children with the rare…
A: The drug known as ivacaftor was developed for the treatment of cystic fibrosis in children who have…
Q: In Drosophila, the yellow (y) gene is near the telomereof the long arm of the acrocentric X…
A: In Drosophila, the yellow (y) gene is present close to the acrocentric X chromosome, whereas, the…
Q: One yeast strain carries the alleles lys+ and arg+, whereas another strain has lys-3 and arg-2. The…
A: Ascus is a structure containing spores produced in fungi after reproduction and in favourable…
Q: In a cross between two varieties of corn, gl1gl1Ws3Ws3(eggparent) x Gl1Gl1ws3ws3 (pollen parent), a…
A: The working segment of DNA that mainly codes for a protein is a gene. Gene itself contains two…
Q: In DrosophilaI, yellow body (y), crossveinless (cv), and forked bristles (f) are all found in the X…
A: According to the question, the map distance between Yellow and crossveinless =14 crossveinlessis…
The a, b, and c loci are all on different chromosomes
in yeast. When a b+ yeast were crossed to a+ b yeast
and the resultant tetrads analyzed, it was found that
the number of nonparental ditype tetrads was equal to
the number of parental ditypes, but there were no tetratype asci at all. On the other hand, many tetratype
asci were seen in the tetrads formed after a c+ was
crossed with a+ c, and after b c+ was crossed with
b+ c. Explain these results.
Trending now
This is a popular solution!
Step by step
Solved in 3 steps
- 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…During ascus formation in Neurospora, any ascosporewith a chromosomal deletion dies and appears whitein color. How many of the eight ascospores in theascus would be white if the octad came from a crossof a wild-type strain with a strain of the oppositemating type carrying:a. a paracentric inversion, and no crossovers occurredbetween normal and inverted chromosomes?b. a pericentric inversion, and a single crossoveroccurred in the inversion loop?c. a paracentric inversion, and a single crossoveroccurred outside the inversion loop?d. a reciprocal translocation, and an adjacent-1segregation occurred with no crossovers betweentranslocated chromosomes?e. a reciprocal translocation, and alternate segregationoccurred with no crossovers between translocatedchromosomes?f. a reciprocal translocation, and alternate segregation occurred with one crossover between translocated chromosomes (but not between thetranslocation breakpoint and the centromereof any chromosome)?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
- 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?On Neurospora chromosome 4, the leu3 gene is just to theleft of the centromere and always segregates at the firstdivision, whereas the cys2 gene is to the right of the centromere and shows a second-division segregation frequency of 16 percent. In a cross between a leu3 strain anda cys2 strain, calculate the predicted frequencies of thefollowing seven classes of linear tetrads where l = leu3 andc = cys2. (Ignore double and other multiple crossovers.)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…
- Map distances were determined for four differentgenes (MAT, HIS4, THR4, and LEU2) on chromosome III of the yeast Saccharomyces cerevisiae:HIS4 ↔ MAT 37 cMTHR4 ↔ LEU2 35 cMLEU2 ↔ HIS4 23 cMMAT ↔ LEU2 16 cMMAT ↔ THR4 20 cMWhat is the order of genes on the chromosome?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? ExplainDRAW IT Suppose, as in the questionat the bottom of Figure 15.9, the parental(P generation) flies were true-breedingfor gray body with vestigial wings andblack body with normal wings. Draw thechromosomes in each of the four possiblekinds of eggs from an F1 female, andlabel each chromosome as “parental”or “recombinant.”
- The alleles his-5 and lys-1, found in baker’s yeast, result in cellsthat require histidine and lysine for growth, respectively. A crosswas made between two haploid yeast strains that are his-5 lys-1and his+ lys+. From the analysis of 818 tetrads, the followingnumbers of tetrads were obtained: 2 spores with his-5 lys+ + 2 spores with his+ lys-1 = 42 spores with his-5 lys-1 + 2 spores with his+ lys+ = 5021 spore with his-5 lys-1 + 1 spore with his-5 lys+ + 1 spore withhis+ lys-1 + 1 spore with his+ lys+ = 312 Compute the map distance between these two genes using firstthe method of calculation that considers double crossovers andthen the one that does not. Which method gives a higher value?Explain why?The alleles his-5 and lys-1, found in baker’s yeast, result in cellsthat require histidine and lysine for growth, respectively. A crosswas made between two haploid yeast strains that are his-5 lys-1and his+ lys+. From the analysis of 818 tetrads, the followingnumbers of tetrads were obtained:2 spores with his-5 lys+ + 2 spores with his+ lys-1 = 42 spores with his-5 lys-1 + 2 spores with his+ lys+ = 5021 spore with his-5 lys-1 + 1 spore with his-5 lys+ + 1 spore withhis+ lys-1 + 1 spore with his+ lys+ = 312A.What is the frequency of single crossovers between these twogenes?B. Based on your answer to part B, how many NPDs are expectedfrom this cross? Explain your answer. Is positive interferenceoccurring?. A diploid strain of yeast was made by mating a haploidstrain with a genotype w−, x−, y−, and z− with a haploidstrain of opposite mating type that is wild type for thesefour genes. The diploid strain was phenotypically wildtype. Four different X-ray-induced diploid mutantswith the following phenotypes were produced fromthis diploid yeast strain. Assume a single new mutation is present in each strain.Strain 1 w− x+ y− z+Strain 2 w+ x− y− z−Strain 3 w− x+ y− z−Strain 4 w− x+ y+ z+When these mutant diploid strains of yeast go throughmeiosis, each ascus is found to contain only two viablehaploid spores.a. What kind of mutations were induced by X-rays tomake the listed diploid strains?b. Why did two spores in each ascus die?c. Are any of the genes w, x, y, or z located on thesame chromosome?d. Give the order of the genes that are found on thesame chromosome