In an electrophoretic gel across which is applied a powerful electrical alternating pulsed field, the DNA of thehaploid fungus Neurospora crassa (n = 7) moves slowlybut eventually forms seven bands, which represent DNAfractions that are of different sizes and hence havemoved at different speeds. These bands are presumed tobe the seven chromosomes. How would you show whichband corresponds to which chromosome?

In an electrophoretic gel across which is applied a powerful electrical alternating pulsed field, the DNA of thehaploid fungus Neurospora crassa (n = 7) moves slowlybut eventually forms seven bands, which represent DNAfractions that are of different sizes and hence havemoved at different speeds. These bands are presumed tobe the seven chromosomes. How would you show whichband corresponds to which chromosome?

Human Heredity: Principles and Issues (MindTap Course List)

11th Edition

ISBN:9781305251052

Author:Michael Cummings

Publisher:Michael Cummings

Chapter6: Cytogenetics: Karyotypes And Chromosome Aberrations

Section: Chapter Questions

Problem 1QP: Analyzing Karyotypes 1. Originally, karyotypic analysis relied only on size and centromere placement...

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A colleague e-mails you saying that she has identified an interesting chromosome variation at 21q13. In discussing this discovery with a friend who is not a cytogeneticist, explain how you would describe this location, defining each term in the chromosome address 21q13.
In an electrophoretic gel across which is applied a powerful electrical alternating pulsed field, the DNA of the haploid fungus Neurospora crassa (n = 7) moves slowly but eventually forms seven bands, which represent DNA fractions that are of different sizes and hence have moved at different speeds. These bands are presumed to be the seven chromosomes. How would you show which band corresponds to which chromosome?
If you expose human tissue culture cells (for example,HeLa cells) to 3H-thymidine just as they enter Sphase, then wash this material off the cells and letthem go through a second S phase before looking atthe chromosomes, how would you expect the 3H to bedistributed over a pair of homologous chromosomes?(Ignore the effect recombination could have on thisoutcome.) Would the radioactivity be in (a) one chromatid of one homolog, (b) both chromatids of one homolog, (c) one chromatid each of both homologs,(d) both chromatids of both homologs, or (e) someother pattern? Choose the correct answer and explainyour reasoning. (This problem extends the analysisbegun in Solved Problem III.)
If you are comparing the two telomeres in each entryin the following list, in which cases would you expectthe two telomeres always to have exactly the samenumber of TTAGGG repeats?a. One telomere at one end of a chromosome, one telomere at one end of a nonhomologous chromosome.b. One telomere at one end of a chromosome, onetelomere at the corresponding end of the homologous chromosome.c. One telomere at one end of a chromosome, theother telomere at the other end of the samechromosome.d. One telomere at one end of a chromatid, the othertelomere at the corresponding position in the sisterchromatid.
If you are comparing the two telomeres in each entryin the following list, in which cases would you expectthe two telomeres always to have exactly the samenumber of TTAGGG repeats?a. One telomere at one end of a chromosome, one telomere at one end of a nonhomologous chromosome.b. One telomere at one end of a chromosome, onetelomere at the corresponding end of the homologous chromosome.
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.)
why The chromatids formedby recombination within the inversion loop of a paracentric inversionheterozygote containtwo centromeres or none, instead of the normal one ?
A heterozygous reciprocal translocation involving 2 non-homologous chromosomes resulted to a new sequence ABCDXYZ and TUVWEFG. Illustrate the chromosomes before and after translocation and the pachytene configuration of the chromosome after translocation.
why The chromatids formedby recombination within the inversion loop of a paracentric inversionheterozygote are genetically unbalanced ?
Consider the following two wild type chromosomes: AB•CDEFGH I•JKLMN What kind of rearrangement is observed in the mutated chromosomes below? AB•CDEKLMNFGH I•J A. reciprocal translocation B. non-reciprocal translocation C. displaced duplication D. pericentric inversion E. paracentric inversion
The human genome consists of 23 pairs of chro-mosomes (22 pairs of autosomes and one pair of sex chro-mosomes). During meiosis, the maternal and paternal setsof homologs pair, and then are separated into gametes, sothat each contains 23 chromosomes. If you assume thatthe chromosomes in the paired homologs are randomlyassorted to daughter cells, how many potential combina-tions of paternal and maternal homologs can be gener-ated during meiosis? (For the purposes of this calculation,assume that no recombination occurs.)
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)?