3. For each of the E. coli strains that follow, indicate the effect of the genotype on expression of the trpE and trpC genes in the presence and absence of Trp. In the wild type (R+ Pt ot att* trpE* trpC*), trpCand trpE are fully repressed in the presence of tryptophan and are fully induced in the absence of tryptophan. R = repressor gene; R" product cannot bind tryptophan; R product cannot bind operator 0 = operator; O cannot bind repressor att = attenuator; att¯ is a deletion of the attenuator P = promoter; P¯ is a deletion of the trp operon a. Rº P+ O* att* trpE* trpC+ b. R* P¯O* att* trpE* trpC/R-P* O* att* trpE¯trpC* c. R+P+O att trpE+ trpC-/R- P+ O attt trpE- trpC+ promoter trpE¯ and trpC are null (loss of function) mutations

3. For each of the E. coli strains that follow, indicate the effect of the genotype on expression of the trpE and trpC genes in the presence and absence of Trp. In the wild type (R+ Pt ot att* trpE* trpC), trpCand trpE are fully repressed in the presence of tryptophan and are fully induced in the absence of tryptophan. R = repressor gene; R" product cannot bind tryptophan; R product cannot bind operator 0 = operator; O cannot bind repressor att = attenuator; att¯ is a deletion of the attenuator P = promoter; P¯ is a deletion of the trp operon a. Rº P+ O att* trpE* trpC+ b. R* P¯O* att* trpE* trpC/R-P* O* att* trpE¯trpC* c. R+P+O att trpE+ trpC-/R- P+ O attt trpE- trpC+ promoter trpE¯ and trpC are null (loss of function) mutations

Biology: The Dynamic Science (MindTap Course List)

4th Edition

ISBN:9781305389892

Author:Peter J. Russell, Paul E. Hertz, Beverly McMillan

Publisher:Peter J. Russell, Paul E. Hertz, Beverly McMillan

Chapter16: Regulation Of Gene Expression

Section: Chapter Questions

Problem 2TYK: For the E. coli lac operon, when lactose is present: a. and glucose is absent, cAMP binds and...

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4. What are the effects of the following conditions on Lac operon of bacteria?A)Glucose is absent and lactose is presentB)Glucose is present and lactose is presentC) Glucose is present and lactose is absent
1. Describe which enzymes are required for lactose and tryptophan metabolism inbacteria when lactose and tryptophan, respectively, are (a) present and (b)absent. 2. Contrast positive versus negative regulation of gene expression. Describe therole of the repressor in an inducible system and in a repressible system.
1. What is the default state of the lac operon? a. LacI repressor is sitting on the operator sequence and blocks RNAP from transcribing lacZYA. b. LacI repressor is not in a correct shape to bind to the operator sequence. c. LacI repressor is not produced in the absence of lactose. d. Allolactose is sitting on the operator sequence and blocks RNAP from transcribing lacZYA.
1. In DNA amplification, using the Taq polymerase, what is the maximum number of amplification cycles? a. 30 b. 20 c. 60 d. 10 2. In the case of trp operon, for transcription to fully occur, which of the following conditions must be met? a. Environmental tryptophan level must be low. b. Environmental tryptophan must be absent. c. Environmental tryptophan level must be abundant. d. Both a and b are correct.
For the E. coli lac operon, when lactose is present: a. and glucose is absent, cAMP binds and activates catabolicactivator protein (CAP). b. and glucose is absent, the level of cAMP decreases. c. activated CAP binds the repressor protein to remove it from the operator gene. d. the cell prefers lactose over glucose. e. RNA polymerase cannot bind to the promoter.
The a/a operon is an inducible operon that controls the production of the sugar arabinose. When arabinose is present in a bacterium it binds to the protein AraC, and the complex binds to the initiator site to promote transcription. In this scenario, AraC is a(n). activator inducer repressor operator
Discuss Concepts In a mutant strain of E. coli, the CAP protein is unable to combine with its target region of the lac operon. How would you expect the mutation to affect transcription when cells of this strain are subjected to the following conditions? Lactose and glucose are both available. Lactose is available but glucose is not. Both lactose and glucose are unavailable.
1. The following are genotypes of merozygotes of E. coli with various combinations of lac operon mutations. Determine the phenotype with respect to beta-galactosidase (z), permease (y), and trans-acetylase (a) of each combination as U = uninducible, I = inducible, and C = constitutive. Choose from the following answers. i- p+ o+ z+ y- a+ / i+ p+ oc z- y- a+ Answer choices UII UIC UUU ICC CUC IUC CCU 2. The following are genotypes of merozygotes of E. coli with various combinations of lac operon mutations. Determine the phenotype with respect to beta-galactosidase (z), permease (y), and trans-acetylase (a) of each combination as U = uninducible, I = inducible, and C = constitutive. Choose from the following answers. i- p+ o+ z- y+ a+ / iS p+ o+ z- y+ a+ Answer choices ICC CCU UII IUC UIC CUC UUU
For each of the E. coli strains that follow, indicate theeffect of the genotype on the expression of the trpEand trpC genes in the presence or absence of tryptophan. [In the wild type (R+ P+ o+ att+ trpE+ trpC+),trpC and trpE are fully repressed in the presence oftryptophan and are fully expressed in the absence oftryptophan.]R = repressor gene; Rnproduct cannot bind tryptophan; R− product cannot bind operatoro = operator for the trp operon; o− cannot bind repressoratt = attenuator; att− is a deletion of the attenuatorP = promoter; P− is a deletion of the trp operonpromotertrpE− and trpC− are null (loss-of-function) mutationsa. R+ P− o+ att+ trpE+ trpC+b. R− P+ o+ att+ trpE+ trpC+c. RnP+ o+ att+ trpE+ trpC+d. R− P+ o+ att− trpE+ trpC+e. R+ P+ o− att+ trpE+ trpC−/R− P+ o+ att+trpE− trpC+f. R+ P− o+ att+ trpE+ trpC−/R− P+ o+ att+trpE− trpC+g. R+ P+ o− att− trpE+ trpC−/R− P+ o− att+trpE− trpC+
4) Suppose you have an E. coli in which the gene that codes for the lac repressor protein has been mutated in such a way that the protein produced can bind to both lactose and DNA (at its specific binding site in the lac operon promoter) simultaneously. What effect, if any, would this have on regulation of expression of the lac operon? Briefly (1 sentence) explain why you would predict the effect or lack of effect this mutation would have.
1. a) If glucose is not available and lactose is absent from the environment, what is the status of transcription of the lac operon genes? Explain your answer from both an evolutionary perspective and in terms of negative and positive regulation of the operon? b)If glucose is not available, but lactose is available from the environment, what is the status of transcription of the lac operon genes? Explain your answer from both an evolutionary perspective and in terms of negative and positive regulation of the operon? b)
2) How does the HAEIII enzyme discriminate between the C-G polymorphism in the TAS2R38 gene?