Exam Questions from Exam 3 Eukaryotic Gene Regulation Genome Modifications in Eukaryotes Population Genetics 1 Consider an autosomal recessive trait that occurs at a frequency of 10 6 in a specific human population that is at Hardy Weinberg equilibrium ie random mating is occurring When answering the following parts show all of your calculations a Draw a pedigree below that shows a mating between two relatives that would correspond to an inbreeding coefficient that equals 0 007813 Denote the mating between relatives with a double bar connecting the two related parents Start your pedigree with the common pair of ancestors and end your pedigree with the two related parents who are mating b Now say that all matings in Generation X of the given population are either between unrelated individuals or have the same inbreeding coefficient as the mating described in part a If the incidence of the trait in Generation X 1 increases to a frequency of 2 X10 6 what percentage of matings in Generation X must have been between unrelated individuals c Now assume that this autosomal recessive trait causes lethality in childhood If a constant percentage of matings are between related parents for many generations would you predict that q would increase OR decrease d A constant percentage of matings has occurred between related parents for many generations and yet you find experimentally that q has not changed Of the three choices below circle ALL that could potentially act against the effect you chose in part c in order to keep q constant Explain in one sentence why you chose or did not choose each option Choice A migration Choice B heterozygote advantage Aa over AA Choice C mutation 2 You are studying regulation of the Wrm1 gene a yeast gene that is expressed in response to heat You isolate a wrm1 lacZ strain that expresses galactosidase when Wrm1 is normally expressed which is at 36 C but not at 24 C You use this wrm1 lacZ strain to perform a genetic screen looking for mutants that do not properly regulate expression of Wrm1 In your screen you isolate a series of mutant strains that either show constitutive or uninducible expression of wrm1 lacZ Your results indicate that the following is the correct pathway for regulation of Wrm1 expression Note that WrmY and WrmX are on the same chromosome and that WrmX WrmZ and Wrm1 are all on different chromosomes heat WrmY WrmX WrmZ Wrm1 One of the mutant strains you isolate contains a mutation called WrmX which is in the coding region of WrmX You mate a WrmX wrm1 lacZ haploid strain to a wrm1 lacZ haploid strain The resulting diploids are white on X gal plates that are incubated at 24 C and are blue on X gal plates that are incubated at 36 C a Classify the WrmX mutation as constitutive OR uninducible b Classify the WrmX mutation as dominant OR recessive c Classify the WrmX locus as cis acting OR trans acting with respect to Wrm1 You next isolate a mutant strain containing a mutation called WrmY which is in the coding region of WrmY You mate a WrmY wrm1 lacZ haploid to a wrm1 lacZ haploid The resulting diploids are white on X gal plates regardless of the temperature at which the plates are incubated d Classify WrmY by the type s of mutation it could be with respect to Wrm1 Your choices are repressor activator UAS URS super activator super repressor dominant negative repressor dominant negative activator You create diploid yeast by mating WrmX WrmY wrm1 lacZ haploid yeast to wrm1 lacZ haploid yeast Sporulation of these diploids yields two types of tetrads and you correctly conclude given the number of each type of tetrad that the WrmX and WrmY loci are linked at a distance of 2 22 cM e Depicted below are the two types of tetrads that resulted when you sporulated the above diploids For each type of tetrad state how many you found of that tetrad out of a total of 90 tetrads classify the tetrad as PD NPD or TT and color in all of the spores that would be blue on each of the following Petri plates Tetrad Type A Number of these tetrads out of a total of 90 Classification of these tetrads PD NPD or TT Color in the spores that would be blue in color when growing on the following plates X gal 24 C X gal 36 C NOTE that the two plates are replicas so the top spore on the left plate has the same genotype as the top spore on the right plate Tetrad Type B Number of these tetrads out of a total of 90 Classification of these tetrads PD NPD or TT Color in the spores that would be blue in color when growing on the following plates X gal 24 C X gal 36 C 3 The scenario in this question asks a biological question that can be addressed by creating genetically engineered mice When creating engineered mice the following 8 steps need to be considered For the mouse you make please state i whether you are using pronuclear injection or gene targeting techniques ii what DNA you would introduce into the mouse cells also draw the DNA iii whether you would put the DNA into a fertilized egg or ES cells iv what is the genotype of the fertilized egg or the ES cells you would start with v where in the mouse genome the DNA you introduced would integrate vi whether creating the mouse should involve the generation of a chimera or not vii which additional breeding steps you would do to make the mouse you wanted viii two possible phenotypic results you could get from the newly made mice and the corresponding conclusions you would make based on each result Non homologous end joining is the process by which a DNA sequence gets inserted into a chromosomal region to which it is not homologous Having a functional copy of the gene NheJ is necessary for this process to occur in mice A mouse with no copies of the NheJ gene is sensitive to irradiation as an adult but a heterozygote is not sensitive You decide to test whether one copy of the Drosophila d Nhe gene could fully compensate for the absence of the mouse NheJ gene You have wild type homozygous mice NheJ NheJ heterozygous mice NheJ NheJ and homozygous mutant mice NheJ NheJ readily available to you 4 You are studying how yeast cells grow on the sugar maltose as a carbon source You find that the sugars maltose and glucose both affect the regulation of the principal enzyme for maltose utilization which is called maltase In yeast cells grown without maltose maltase is not expressed but maltase is induced when maltose is added to the growth medium In cells grown in medium that contains both maltose and glucose maltase is not expressed You have isolated
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