Concept explainers
(a)
To describe: The two different mutations which would result in auvrA constitutive
Introduction: Mutation is the process of changes at the genetic level in which the coding of the DNA is altered by the chemical, radiation, and environmental factors. These factors are termed as mutagens. Mutagens are capable to induce mutation in an individual.
(b)
To describe: The outlined series of a genetic experiment that makes use of diploid strains for the determination of the possible mutations that have been isolated.
Introduction: Mutations are the changes in the sequence of DNA which may be harmful or useful for an individual. It leads to evolution and the better survival of an individual. The mutations can be inherited or acquired.
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Concepts of Genetics (12th Edition)
- . In the tryptophan operon of E. coli, what happens when tryptophan levels get too high? tryptophan is removed from its co-repressor, causing it to detach from the operator tryptophan is removed from its co-repressor, causing it to attach to the operator tryptophan is bound to its co-repressor, causing it to detach from the operator tryptophan is bound to its co-repressor, causing it to attach to the operator all of the above occur at equal rates when tryptophan levels get too higharrow_forwardIn lac operon, both gene A and gene B undergo a transcription process. Gene B can only undergo transcription in the presence of lactose and in the absence of glucose. The product of gene A is often altered by an inducer. Which of the following is true about genes A and B? Select one: a. Gene A= structural gene; Gene B= regulatory gene b. Gene A= regulatory gene; Gene B= structural gene c. Gene A= promoter gene; Gene B= operator gene d. Gene A= lacZ gene; Gene B= promoter genearrow_forwardYou are growing E. coli in a laboratory in order to study their operons. The growth media you are using contains lactose, no glucose and no tryptophan. Using your knowledge of operons and their regulation, answer the following questions Which operons would be functional under these conditions? 2. What repressors would be made? (NOTE: name the repressors using their gene names) 3.Which repressor(s) would be made in the inactive form? 4.Which repressor(s) would be made in the active form? 5.Which repressor(s) under these conditions can bind the operator sequence? 6.Which repressor(s)under these conditions cannot bind the operator sequence?arrow_forward
- You are growing E. coli in a laboratory in order to study their operons. The growth media you are using contains lactose, no glucose and no tryptophan. Using your knowledge of operons and their regulation, answer the following questions using the dropdown menus provided in Canvas. Which operons would be functional under these conditions? What repressors would be made? (NOTE: name the repressors using their gene names) Which repressor(s) would be made in the inactive form? Which repressor(s) would be made in the active form? Which repressor(s) under these conditions can bind the operator sequence?arrow_forwardYou are growing E. coli in a laboratory in order to study their operons. The growth media you are using contains lactose, no glucose and no tryptophan. Using your knowledge of operons and their regulation, answer the following questions using the dropdown menus provided in Canvas. Which operons would be functional under these conditions? What repressors would be made? (NOTE: name the repressors using their gene names) Which repressor(s) would be made in the inactive form? Which repressor(s) would be made in the active form? Which repressor(s) under these conditions can bind the operator sequence? Which repressor(s)under these conditions cannot bind the operator sequence? What effect does lactose have on the bacterial cell’s lac operon? What does the absence of glucose do to the bacterial cell? You now add tryptophan to the cell. What would happen to the bacterial cell and its trp operon? What kind of regulation does lactose provide to an operon’s…arrow_forwardThe lac operon consists of three structural genes, lacZ, lacY and lacA that are transcribed as a single polycistronic mRNA. You are given a new strain of Escherichia coli with the following lac operon genotype: p+0°Z•Y*A +// P*O*Z*Y+ A- (i) Explain how the lac I ³ gene affects gene expression.arrow_forward
- The amino acid asparagine is synthesized from aspartic acid by the enzyme asparagine synthetase (AS). In the previous problem you proposed a model for how this gene could be regulated. Suppose that you carry out an experiment to test your model. To do this you cut out the regulatory sequences upstream of the gene and fuse it to a gene for green fluorescent protein (GFP). Now you can visually observe when the gene is activated. You insert this engineered gene into a host cell and look for GFP expression. You discover some mutants that have different expression levels of GFP and call them GFP1- and GFP2-. The expression levels of GFP are given below. Cell GFP expression Wild type 100 GFP1- 50 GFP2- 0 Propose an explanation for these results based on your model. In other words, what was mutated and how? Your answer should include whether the mutation is (see links for more information): dominant or recessive https://www.ncbi.nlm.nih.gov/books/NBK21578/#A1877…arrow_forwardIn the absence of lactose and the lacI repressor gene is mutated such that the repressor protein product can no longer bind to the operator, the structural genes will: [ Select ] ["No longer be expressed", "Be constantly expressed", "Be deleted from the operon"] In the presence of lactose and the lacI repressor gene is mutated such that the repressor protein product can no longer bind to the operator, the structural genes will: [ Select ] ["No longer be expressed", "Be constantly expressed", "Be deleted from the operon"]arrow_forwardIn the tryptophan operon of E. coli, what happens when tryptophan levels get too high? tryptophan is removed from its co-repressor, causing it to detach from the operator tryptophan is removed from its co-repressor, causing it to attach to the operator tryptophan is bound to its co-repressor, causing it to detach from the operator tryptophan is bound to its co-repressor, causing it to attach to the operator all of the above occur at equal rates when tryptophan levels get too high (Option D is the answer for the question above) What effect will the above process have on the tryptophan operon? RNA polymerase will detach from the promoter, initiating transcription RNA polymerase will detach from the promoter, stopping transcription RNA polymerase will attach to the promoter, initiating transcription RNA polymerase will attach to the promoter, stopping transcription all of the above occur at equal rates when tryptophan levels get too higharrow_forward
- In the tryptophan operon of E. coli, what happens when tryptophan levels get too high? tryptophan is removed from its co-repressor, causing it to detach from the operator tryptophan is removed from its co-repressor, causing it to attach to the operator tryptophan is bound to its co-repressor, causing it to detach from the operator tryptophan is bound to its co-repressor, causing it to attach to the operator all of the above occur at equal rates when tryptophan levels get too high What effect will the above process have on the tryptophan operon? RNA polymerase will detach from the promoter, initiating transcription RNA polymerase will detach from the promoter, stopping transcription RNA polymerase will attach to the promoter, initiating transcription RNA polymerase will attach to the promoter, stopping transcription all of the above occur at equal rates when tryptophan levels get too higharrow_forwardWhat would happen to the regulation of the tryptophan operon in bacterial cells that express a mutant form of the tryptophan repressor that (1) cannot bind to DNA, (2) cannot bind tryptophan, or (3) binds to DNA even in the absence of tryptophan?arrow_forwardYou have isolated different mutants (reg1 and reg2) causing constitutive expression of the emu operon (which has genes emu1 and emu2). One mutant contains a defect in a DNA-binding site, and the other has a loss-of-function defect in the gene encoding a protein that binds to the site Say you don’t know which mutant has a defect in the site and which one has a mutation in the binding protein. To figure it out, you construct the two partial diploid strains (i and ii below), and you then assay the levels of the Emu1 and Emu2 proteins in these two strains. F’ (reg1- reg2+ emu1- emu2+) / reg1+ reg2+ emu1+ emu2- F’ (reg1+ reg2- emu1- emu2+) / reg1+ reg2+ emu1+ emu2- What proteins do you predict will be expressed for strains i and ii if reg2 encodes the regulatory protein and reg1 is the regulatory site?arrow_forward
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