pa norhing 13. A transcription factor with the misleading name Catabolite Repressor Protein (CRP) regulates expression of operons involved in metabolism of alternative sugars including the Mal operon coding for Ma!E, MalF, and MalG. Based on your knowledge of the role of CRP in regulation of the Lac operon, you would expect that strains with a mutation inactivating CRP would: a. display wildtype expression of MalE, MalF, and MalG under all conditions b. display constitutive expression of MalE, MalF, and MalG be unable to fully induce the expression of MalE, MalF, and MalG d. be unable to utilize glucose e. both b and d deloeiot.ons.rllod bn

pa norhing 13. A transcription factor with the misleading name Catabolite Repressor Protein (CRP) regulates expression of operons involved in metabolism of alternative sugars including the Mal operon coding for Ma!E, MalF, and MalG. Based on your knowledge of the role of CRP in regulation of the Lac operon, you would expect that strains with a mutation inactivating CRP would: a. display wildtype expression of MalE, MalF, and MalG under all conditions b. display constitutive expression of MalE, MalF, and MalG be unable to fully induce the expression of MalE, MalF, and MalG d. be unable to utilize glucose e. both b and d deloeiot.ons.rllod bn

Biochemistry

6th Edition

ISBN:9781305577206

Author:Reginald H. Garrett, Charles M. Grisham

Publisher:Reginald H. Garrett, Charles M. Grisham

Chapter29: Transcription And The Regulation Of Gene Expression

Section: Chapter Questions

Problem 8P: Alternative Splicing Possibilities Suppose exon 17 were deleted from the fast skeletal muscle...

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Regulation of Genes and Their products 1. Given the following genotypes, explain how the mutation (identified by a (-) superscript) wil affect E. coll grown in lactose medium. Will the lac operon be on or off? Will there be a complete set of gene products from the lac operon? What will be the implication of the missing gene product, if ever? Will the cell be able to survive in the lactose medium or not? a. I+p+o+z- y+ b. i- p+o+z+y+ c. i+p+o- z+y+ d. i+p- o+z+y+ 2. In terms of the trp operon, differentiate between two normal bacterial cultures, one grown in a medium supplied with tryptophan and the other medium without tryptophan. 3. Experiments show that mutations at gene E lead to non-repressible transcription of trp genes. Why?
Alternative Splicing Possibilities Suppose exon 17 were deleted from the fast skeletal muscle troponin T gene (Figure 29.46). How many different mRNAs could now be generated by alternative splicing? Suppose that exon 7 in a wild-type troponin T gene were duplicated. How many different mRNAs might be generated from a transcript of this new gene by alternative splicing?
Substrate Binding by RNA Polymerase RNA polymerase has t binding sites for ribonucleoside triphosphates: the initiation site and the elongation site. The initiation site has a greater Km for NTPs than the elongation site. Suggest what possible significance this fact might have for the control of transcription in cells.
Explain why (a) inactivation of the O2 or O3 sequence of the lac operon causes only a twofold loss in repression, and (b) inactivation of both O2 and O3 reduces repression ∼70-fold.
. An interesting mutation in lacI results in repressorswith 110-fold increased binding to both operator andnonoperator DNA. These repressors display a “reverse”induction curve, allowing β-galactosidase synthesis inthe absence of an inducer (IPTG) but partly repressingβ-galactosidase expression in the presence of IPTG. Howcan you explain this? (Note that, when IPTG binds a repressor, it does not completely destroy operator affinity,but rather it reduces affinity 110-fold. Additionally, ascells divide and new operators are generated by thesynthesis of daughter strands, the repressor must findthe new operators by searching along the DNA, rapidlybinding to nonoperator sequences and dissociating fromthem.)
Suppose that a new mutation lacIes, ('es' stands for ‘extra-strength’) has been discovered in the lac operon that allows the lac-repressor to bind even to the lacOc operator. Other properties of lacIes repressor remain normal (that is the same as of lacI+). Given this genotype Is P+ Oc Z+ Y- / Ies P+ O+ Z+ Y+ , under which conditions will the gene lacZ be transcribed to produce β-galactosidase and the gene lacY transcribed to produce permease? A) With lactose, β-galactosidase and permease are produced, without lactose they are not produced B) With lactose, β-galactosidase is produced, without lactose it is not; permease is never produced C) β-galactosidase is always produced and permease is never produced D) With lactose, β-galactosidase and permease are produced, without lactose they are also produced E) β-galactosidase is always produced and permease is produced only in the presence of lactose
True/False: In general, weak promoters that support active transcription have -10 and -35 boxes that are close to the consensus sequences and a spacer between the two boxes that is 17 +/- 1 bp.
1) Histone methylation can have many different effects on gene expression. In some cases, histone methylation is associated with activation of transcription, whereas in other cases it can trigger the formation of heterochromatin and a decrease in transcription. If histone methylation has been detected in the region of gene YFG in yeast, describe an experiment that could distinguish whether the methylation is important to activate or repress transcription of gene YFG. 2) An E. coli strain of chromosomal genotype lacI lacP lacO lacZ lacY . You wish to transform this strain into a wild-type lac operon by the addition of an extra piece of DNA (plasmid). What regulatory region(s), gene or genes would you add on this extra DNA that would make this strain express the lac operon genes as wild type? How would you design this plasmid if you want the strain of E. coli to express the lac operon genes even if lactose is absent in the medium (constitutively)?
88Sequential binding of RNA polymerase II-TFIIF complex, TFIIE, and TFIIH completes ___________________ formation. A.pre-initiation complexb.TF recognition elementc.pre-elongation complexD.TATA binding complex 89Which of the following is the GDP-GTP exchange protein?A.EF-Tub.none of the abovec.EF-TsD.EF-G 90RNA polymerase II has 14 subunits. Yesorno
Gal 4 is involved in the regulation of galactose metabolism. Describe how transcription would be affected in the presence of a mutation that resulted in an inability of Gal80 to enter the nucleus?
In addition to Tc1, the C. elegans genome contains otherfamilies of DNA transposons such as Tc2, Tc3, Tc4, andTc5. Like Tc1, their transposition is repressed in thegerm line but not in somatic cells. Predict the behaviorof these elements in the mutant strains where Tc1 is nolonger repressed due to mutations in the RNAi pathway.Justify your answer.
Transcription AttenuationHow would transcriptionof the E. coli trp operon be affected by the following manipulations of the leader region of the trp mRNA?(a) Increasing the distance (number of bases) betweenthe leader peptide gene and sequence 2(b) Increasing the distance between sequences 2 and 3(c) Removing sequence 4(d) Changing the two Trp codons in the leader peptidegene to His codons(e) Eliminating the ribosome-binding site for the genethat encodes the leader peptide(f) Changing several nucleotides in sequence 3 so thatit can base-pair with sequence 4 but not with sequence 2