Lactose permease is encoded by the lacY gene of the lac operon.Suppose a mutation occurred at codon 64 that changed the normalglycine codon into a valine codon. The mutant lactose permease isunable to function. However, a second mutation, which changescodon 50 from an alanine codon to a threonine codon, is able torestore function. Is each of the following terms appropriate or inappropriate to describe this second mutation?A. ReversionB. Intragenic suppressorC. Intergenic suppressorD. Missense mutation

Lactose permease is encoded by the lacY gene of the lac operon.Suppose a mutation occurred at codon 64 that changed the normalglycine codon into a valine codon. The mutant lactose permease isunable to function. However, a second mutation, which changescodon 50 from an alanine codon to a threonine codon, is able torestore function. Is each of the following terms appropriate or inappropriate to describe this second mutation?A. ReversionB. Intragenic suppressorC. Intergenic suppressorD. Missense mutation

Name: Lactose permease is encoded by the lacY gene of the lac operon.Suppose
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Description: Lactose permease is encoded by the lacY gene of the lac operon.Suppose a mutation occurred at codon 64 that changed the normalglycine codon into a valine codon. The mutant lactose permease isunable to function. However, a second mutation, which chang

Biology (MindTap Course List)

11th Edition

ISBN:9781337392938

Author:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. Berg

Publisher:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. Berg

Chapter14: Gene Regulation

Section: Chapter Questions

Problem 11TYU

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In addition to observing similarities to the lac operon, you also notice that this gene is regulated via attenuation, similar to the trp operon. Based on this similarity to this model operon, you could state that ___________. Group of answer choices If a terminator loop forms in the DNA, the expression of the structural genes is halted. The formation of the terminator hairpin followed by a series of Uracil (UUUUUUU) functions similar to Rho-Independent termination to result in the stopping of transcription. The transcription of a leader sequence affects the translation of the structural genes. Never mind – all of these statements are true! Attenuation will be the primary means of transcriptional regulation, with a repressor used as a back up option.
The lac operon consists of regulatory regions such as the promoter as well as the structural genes lacZ, lacY, and lacA, which code for proteins involved in lactose metabolism. What would be the outcome of a mutation in lacA?
. Listed in parts a through g are some mutations that were found in the 5′ UTR of the trp operon of E. coli. What will the most likely effect of each of these mutations be on the transcription of the trp structural genes? Q. A mutation that changes the Trp codons in region 1 of the mRNA 5′ UTR into codons for alanine
Arginine is one of the amino acids that serves as a building block for protein synthesis. Arginine biosynthesis depends on the expression of the arg operon, which encodes ArgC (a reductase) and ArgB (acetylglutamate kinase). Which of the following statements regarding mutation of the arginine biosynthesis repressor ArgR is true? O A 1-bp insertion in the argR gene would result in a mutant able to grow in the absence of arginine, O A 1-bp deletion in the argB gene would result in a mutant unable to transcriptionally regulate the arg operon encoding argB. O A 1bp insertion in the argC gene would result in a mutant able to grow in the absence of arginine. O A 1-bp deletion in the argR gene would result in a mutant that represses the arg operon when grown in the presence of arginine. None of the above.
Explain why inactivation of the O1 sequence of the lac operator almost completely abolishes repression of the lac operon.
. Listed in parts a through g are some mutations that were found in the 5′ UTR of the trp operon of E. coli. What will the most likely effect of each of these mutations be on the transcription of the trp structural genes? Q. Deletions in region 3 of the mRNA 5′ UTR
In the lac operon (below), how will expression of the genes lacZ and lacy be effect by a mutation in the repressor protein (encoded by lach) that prevents it from binding the operator sequence (lacO) in the absence of lactose? Explain the answer
. Listed in parts a through g are some mutations that were found in the 5′ UTR of the trp operon of E. coli. What will the most likely effect of each of these mutations be on the transcription of the trp structural genes? Q. A mutation that prevents the binding of the ribosome to the 5′ end of the mRNA 5′ UTR
In the topic about prokaryotic gene expression regulation, we learned about the LacI-, LacIS, and LacOc mutations. Based on your knowledge of allosteric regulation, invent and describe a hypothetical mutation that would produce constitutive expression of the Lac operon but is not a mutation that occurs in the Lac operator (that is, it must be a different mutation than a LacOc type mutation) and is not a mutation to the DNA binding domain of LacI (that is, it must also be a different mutation than a LacI- type mutation). Clearly mention where in the prokaryotic genome this mutation would occur, and explain the logic behind how that mutation would produce constitutive Lac operon expression.
Mutation in the regulatory gene in the lac operon results in the formation of an inactive repressor. List and explain the effect of such a mutation on the expression of the structural gene for lactose in E.coli?
In the lac operon system, do the inducers act at the transcription or translation level? Explain why it acts in that level in a short but concise way.
Imagine that a new strain of E. coli is discovered, and it contains the following novel genetic region including the lacI gene and the lac operon: *see image* Upstream of the promoter associated with the lac operon, there is a new operator element "Oν" (O-"nu"). This new operator has high sequence homology to O1, the DNA element that is bound with the highest affinity by the lac repressor. What would be the impact of this new genetic element regarding behavior of the operonin the absence (vs. the presence) of lactose and allolactose? Answer in terms of the protein levels of the lac repressor, as well as the proteins encoded by the genes lacZ/Y/A in the downstream region of the operon. Remember that proteins, once expressed/generated, will not persist forever, and that they have a natural lifetime (ending when they are degraded by the cell).