Operons are a common feature of bacterial genomes. Which of the following statements about the lac operon is correct? 1. The lac operon contains 3 stop codon sequences. 2. The lacz gene codes for lactose which is used as a source of energy. 3. A lacl mutant that can't bind to allolactose will inhibit the transcription of lacZ, lacY and lacA. 4. A lacOC mutant that keeps the operator constitutively ON (regardless of repressor binding), will inhibit the transcription of lacZ, lacY and lacA. O A. 1, 2 and 3 O B. 1 and 3 O C. 2 and 4 O D. 4 only O E. All of 1, 2, 3 and 4 are correct

Operons are a common feature of bacterial genomes. Which of the following statements about the lac operon is correct? 1. The lac operon contains 3 stop codon sequences. 2. The lacz gene codes for lactose which is used as a source of energy. 3. A lacl mutant that can't bind to allolactose will inhibit the transcription of lacZ, lacY and lacA. 4. A lacOC mutant that keeps the operator constitutively ON (regardless of repressor binding), will inhibit the transcription of lacZ, lacY and lacA. O A. 1, 2 and 3 O B. 1 and 3 O C. 2 and 4 O D. 4 only O E. All of 1, 2, 3 and 4 are correct

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 9TYU: A mutation that inactivates the repressor gene of the lac operon results in (a) the continuous...

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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
As diagrammed below, some amino acid biosynthetic operons have stem loop structures in the mRNA. These structures play a role in the regulation of the operon by which of the following mechanisms? Translation stop codon- Attenuator loop. mRNA 5' 3' DNA attenuator trpE O Catabolite repressor protein can bind and prevent the hairpins from forming thus allowing translation to occur. O The leader sequence shown contains codons for the amino acid. When these are low, the ribosome stalls, allowing a hairpin between the two middle regions to form so that the rest of the message can be translated. In the presence of large amounts of the amino acid, the hairpin will wind around the amino acid and prevent further translation. O A repressor protein made of that amino acid will bind to the region and prevent translation when large amounts of the amino acid are present. O The uridine-rich region has codons for that amino acid; when present, this region will be a terminator region. The hairpins allow…
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.
Strain P77 has a mutation in the lacO that prevents it from being bound by the lacI protein. Otherwise all other parts of the operon are functional. 1. Can strain P77 metabolize lactose if it is present? 2. If lactose is absent, will strain P77 transcribe its lac operon? 3. If lactose is present, will strain P77 transcribe its lac operon?
Which of the following statements about the trp operon is false? If a mutation in region 2 prevents the formation of the 2 + 3 loop in the 5’UTR transcription levels will increase. The trp operon is an example of negative repressible operon. Formation of the anti-terminator in the 5’UTR of the trp operon occurs when trp levels are low. In the presence of high trp-tRNA, the genes of the trp operon are not expressed. The role of trp is to bind to the repressor protein and activate it.
All of the following statements about the repressor of the lac operon of E. coli are true EXCEPT which one? O A. The repressor is the product of a regulatory gene i The repressor binds to the operator region of the DNA of the lac OB. operon. The repressor is a protein. OC. The repressor interacts with the operator in such a way as to OD. prevent translation of beta-galactosidase. The repressor can combine with lactose to form a OE. complex that will no longer bind to the operator region. QUESTION 32 The amino acid which is a precursor of serotonin is Histidine OA. O B. Tyrosine O C. Glutamate D. Tryptophan O E. none of the above
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.
Strain ROFL4 has a premature stop mutation in the lacZ gene, resulting in a nonfunctional b-galactosidase. Otherwise all other parts of the operon are functional. 1. Can strain ROFL4 metabolize lactose if it is present? 2. If lactose is absent, will strain ROFL4 transcribe its lac operon? 3. If lactose is present, will strain ROFL4 transcribe its lac operon?
Strain HK180 has lac operon with a nonfunctional lacP. Otherwise all other parts of the operon are functional. 1. Can strain HK180 metabolize lactose if it is present? 2. If lactose is absent, will strain HK180 transcribe its lac operon? 3. If lactose is present, will strain HK180 transcribe its lac operon?
Strain LOLZ has a mutation in the lacI gene that results in a lacI protein that cannot bind allolactose. Otherwise all other parts of the operon are functional. 1. Can strain LOLZ metabolize lactose if it is present? 2. If lactose is absent, will strain LOLZ transcribe its lac operon? 3. If lactose is present, will strain LOLZ transcribe its lac operon?
A constitutive mutation in the lac operon may be of several types. [Note that constitutive means that the structural genes are always expressed, even if lactose is absent.] Name two types of constitutive mutations. Group of answer choices LacY- and LacI- LacOc and LacZ- LacZ- and LacI- LacY- and LacA- LacI- and LacOc
What are the effects of the following conditions on Lac operon of bacteria? 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