Concept explainers
To review:
The hypothesis to explain the formation of two different mutant
Introduction:
Transposable elements in yeast belongs to a family of dispersed and repeated retrotransposons in the genome of Saccharomyces cerevisiae. Saccharomyces cerevisiae is an important model organism to study the LTR (long terminal repeats)-retrotransposons biology. Five retrotransposon families are present in S. cerevisiae, designated as Ty1-Ty5. These Ty elements have a tendency to influence the genome organization. These Ty elements are the causal agents of mutation and genome rearrangment through recombination.
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Chapter 15 Solutions
Biology: The Dynamic Science (MindTap Course List)
- Geneticists often use ethylmethane sulfonate (EMS) to induce mutations in Drosophila. Why is EMS a mutagen of choice for genetic research? What would be the effects of EMS in a strain of Drosophila lacking functional mismatch repair systems?arrow_forwardThe genetic alteration responsible for sickle-cell anemia in humans involves: a transition mutation from A to G, substituting glutamic acid for valine in a-globin a transversion mutation from T to A, substituting valine for glutamic acid in b-globin a transition mutation from T to C, substituting valine for glutamic acid in b-globin a transversion mutation from G to C, substituting glutamic acid for valine in a-globin a frameshift mutation of one ATC codon, removing glutamic acid from b-globinarrow_forwardA strain of Arabidopsis thaliana possesses a mutation in the APETALA2 gene. As a result of this mutation, much of the 3′ UTR of the mRNA transcribed from the gene is deleted. What is the most likely effect of this mutation on the expression of the APETALA2 gene?arrow_forward
- In a line of human cells grown in culture, a geneticist isolates a temperature-sensitive mutation at a locus that encodes an acetyltransferase enzyme; at temperatures above 38°C, the mutant cells produce a nonfunctional form of the enzyme. What would be the most likely effect of this mutation if the cells were grown at 40°C?arrow_forwardIn the galactose operon of Escherichia coli, a repressor, encoded by the galR gene, binds to an operator site, galo, to regulate the expression of three structural genes, galE, galT, and galK. Expression is induced by the presence of galactose in the media. For each of the strains listed, would the cell show constitutive, inducible, or no expression of each of the structural genes? (Assume that galR−is a loss-of-function mutation.) galR− galo+ galE+ galT+ galK+ galR+ galoc galE+ galT+ galK+ galR− galo+ galE+ galT+ galK−/ galR+ galo+ galE− galT+ galK+ galR− galoc galE+ galT+ galK−/ galR+ galo+ galE− galT+ galK+arrow_forwardThe cyanobacterium Oscillatoria sancta appears reddish-brown when grown under green light but alters its gene expression patterns and becomes blue-green when grown under red light. Explain this observation.arrow_forward
- You are studying the tryptophan synthetase gene that Yanofsky also examined to determine the relationship between the nucleotide sequence and the amino acid sequence of the gene. Yanofsky found a large number of mutations that affected the tryptophan synthetase gene. A) If you took this mutant E. Coli line (that has an Arginine at this location) and exposed it to a mutagen that could potentially change bases, what are the second mutations you would most likely discover that would restore the activity of the tryptophan synthetase gene and where would it be located? B) Most of the mutations that Yanofsky recovered were missense mutations. However, Yanofsky also recovered a nonsense mutation that changed amino acid number 15 into a stop codon. This codon normally encodes Lysine. Does the recovery of this mutation support the hypothesis that this Lysine residue is critical in the function of the tryptophan synthetase protein?arrow_forwardAfter mutagenesis of wild type Vibrio fisheri, you isolate two different mutant strains (A and B) that, unlike the wild type cells, fail to luminesce when grown to high density in a flask with appropriate medium. Curiously, however, when you inoculate both mutant strains in the same flask, you observe that the mixed (A+B) culture begins to emit light after growing dense. a) What gene/functions are likely affected in each of the two mutants? b) How does this explain their phenotypes?arrow_forwardIn site-directed mutagenesis experiments of an enzyme, scientists altered an aspartate residue to glutamate, lysine, phenylalanine, or valine. Which substitution is expected to have the least effect on enzymatic acitivity? Group of answer choices Glutamate Valine Lysine Phenylalaninearrow_forward
- A mutant strain of Salmonella bacteria carries a mutation of the rho protein that has fully activity at 37°C but is completely inactivated when the mutant strain is grown at 40°C. a)Speculate about the kind of differences you would expect to see if you compared a broad spectrum of mRNAs from the mutant strain grown at 37°C and the same spectrum of mRNAs from the strain when grown at 40°C. b)Are all the mRNAs affected by the rho protein mutation in the same way? Why or why not?arrow_forwardThe SARS-CoV-2 genome has a cap at its 5'-end that is the same as the one seen on most human mRNA molecules. The nsp12 RNA-dependent RNA polymerase acts like cellular RNA polymerase and initiates RNA synthesis by synthesizing a dinucleotide from two nucleoside triphosphates. What other enzymes are needed to add a cap to the nsp12 product? Describe the chemical nature of the products of each of these enzymesarrow_forwardOchre and amber are two distinct nonsense mutations. Before the genetic code was worked out, Sydney Brenner, Anthony O. Stretton, and Samuel Kaplan applied different types of mutagens to bacteriophages in an attempt to determine the bases present in the codons responsible for amber and ochre mutations. They knew that the ochre and amber mutations were suppressed by different types of suppressor mutations, which demonstrated that each is a different stop codon. They obtained the following results: (1) A single-base substitution could convert an ochre mutation into an amber mutation. (2) Hydroxylamine induced both ochre and amber mutations in wildtype phages. (3) 2-Aminopurine caused ochre to mutate to amber. (4) Hydroxylamine did not cause ochre to mutate to amber. These data do not allow the complete nucleotide sequence of the amber and ochre codons to be worked out, but they do provide some information about the bases found in the nonsense mutations. a. What conclusions about the…arrow_forward
- Biology: The Dynamic Science (MindTap Course List)BiologyISBN:9781305389892Author:Peter J. Russell, Paul E. Hertz, Beverly McMillanPublisher:Cengage Learning