6. Which of the following is true about E. coll's lac operon? If there is no lactose present, the operon catabolizes glucose to produce ATP The three genes of the lac operon (lacz. lacy and lacA) have their own promoters, thus they are transcribed separately. The lac operon repressor binds to the operator in order to activate and enhance the transcription of the three lac genes. The allolactose-repressor complex binds to the lac operon operator thereby increasing the expression of the operon.

6. Which of the following is true about E. coll's lac operon? If there is no lactose present, the operon catabolizes glucose to produce ATP The three genes of the lac operon (lacz. lacy and lacA) have their own promoters, thus they are transcribed separately. The lac operon repressor binds to the operator in order to activate and enhance the transcription of the three lac genes. The allolactose-repressor complex binds to the lac operon operator thereby increasing the expression of the operon.

Biology 2e

2nd Edition

ISBN:9781947172517

Author:Matthew Douglas, Jung Choi, Mary Ann Clark

Publisher:Matthew Douglas, Jung Choi, Mary Ann Clark

Chapter16: Gene Expression

Section: Chapter Questions

Problem 9RQ: The a/a operon is an inducible operon that controls the production of the sugar arabinose. When...

See similar textbooks

Similar questions

A mutation that inactivates the repressor gene of the lac operon results in (a) the continuous transcription of the structural genes (b) no transcription of the structural genes (c) the binding of the repressor to the operator (d) no production of RNA polymerase (e) no difference in the rate of transcription
1. Draw a diagram of the lac operon. PO I+P+O+Z+Y+ I+P+OcZ+Y- I-P+O+Z+Y+ Lab section (circle): lacz gene lac Y gene lacA gene I+P+O+ZY/IPO+Z+Y- 2. The promoter (P) is the start site of transcription through the binding of RNA polymerase before actual mRNA production. Mutated promoters (P) cannot bind RNA polymerase, so no mRNA is made. In the table below, make predictions about the expression of ß-galactosidase and permease for different partial diploid (F') genotypes. Do this for E. coli growth on two different types of media - one without lactose, and one with. Use a to mark where there is no enzyme produced, and a + to mark where the enzyme is made. The first genotype has all wild-type alleles, and has been filled in as an example. Genotype IPOCZ+Y/I-P+O+Z-Y+ ISP+O+Z+Y/I+P+O+Z*Y* CR 1:00 Lactose absent B-galactosidase Permease R 3:-00 + R 6:30 Lactose present B-galactosidase F 10:00 Permease
2. The lac operon controls the inducible expression of genes involved in lactose utilization. Several naturally occurring mutations have been discovered that affect how the lac operon operates. Consider the following mutations: I-= a mutation in the repressor protein that cannot bind the operator Is = a mutation in the repressor protein that cannot be removed from the operator Oc= a mutation in the operator that cannot bind the repressor Detail the functionality of the lac operon with following genotypes and cellular conditions (Note if there is no superscript, there is no mutation) Genotype I, O I, OC IS, O I, O Is, Oc Lactose present No No Yes Yes No Repressed (yes/no) N VAS ves NO Constitutive (yes/no) NO NO YES Yes NO Inducible (yes/no) Yes yes NO NO YUS
28. Which statement does NOT explain why the lac operon would not be effectively regulated by an attenuation mechanism like the trp operon? 1.Lactose is a substrate for the lac operon protein products. 2.Products of lac operon enzymes are not used in protein synthesis. 3.Transcription and translation do not happen simultaneously for the lac operon. 4.Attenuation is a suitable regulatory mechanism for anabolic amino acid pathways. 5.All of these statements explain why regulation by attenuation would not be effective for the lac operon.
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.
10. Modify the diagrams below to reflect the activation and repression of lac operon. Use arrows, lines, X's, etc. to illustrate control of gene expression.S a. Activation lactose lactose CAP lac I repressor allolactose b. Repression CAP allolactose lac I repressor CAMP с CAMP с promoter operator +1 RNA Pol +1 RNA Pol promoter operator lac Z lac Z lac Y lac Y lac A lac A DNA DNA
Indicate whether each of the following statements about the lac operon are true or false: Bacteria with a lac phenotype are unable to use lactose because of some defect in expressing the genes A constitutive Lac+ phenotype could mean either that the production of repressor is defective or that the operator sequence is defective The lacl gene is next to, but is not part of, the lac 1. TRUE operon 2. FALSE Bacteria with a lac* phenotype cannot grow on media containing lactose as the only sugar The structural genes of the lac operon are each transcribed as a separate MRNA Expression of the Lac Repressor from the lacl promoter is regulated by lactose
Describe the main functional differences between the TRP and the Lac operons. Main functional differences DO NOT refer to the fact that one operon involves TRP and the other involves Lac. They also don’t include that there are different genes found in the TRP operon compared to the Lac operon or that the repressor in the Lac operon is called Lac l. Also DO NOT simply list how both operons work to answer this question.
What are the effects of the following conditions on Lac operon of bacteria? Please do not forget to mention about the role of repressor, activator, RNA polymerase in each case. Glucose is absent and lactose is present Glucose is present and lactose is present Glucose is present and lactose is absent
Match each of the following mechanisms with how it can change the levels of gene products--whether on different operons or within the same operon. Different promoters might have different DNA sequences Translation initiation sequences can cause different open reading 1. Differences in mRNA levels BETWEEN operons frames to be translated 2. Differences in protein levels WITHIN an operon differently. The secondary structures of MRNA can differ which can change the rate of degradation of transcripts.
. Mutants were isolated in which the constitutive phenotype of a missense lacI mutation was suppressed.That is, the operon was now inducible. These suppressor mutations mapped to the operon, not to the lacIgene. What could these mutations be?
9. A single base substitution mutation in lacY gene of the Lac operon would render the entire lac operon nonfunctional. True or False.