Concepts of Genetics (12th Edition)
12th Edition
ISBN: 9780134604718
Author: William S. Klug, Michael R. Cummings, Charlotte A. Spencer, Michael A. Palladino, Darrell Killian
Publisher: PEARSON
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Chapter 16, Problem 19ESP
In a theoretical operon, genes A, B, C, and D represent the repressor gene, the promoter sequence, the operator gene, and the structural gene, but not necessarily in the order named. This operon is concerned with the
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Students have asked these similar questions
The streptolysin S toxin made by S. pyogenes is encoded by a 9-gene
operon, sagABCDEFGHI. Thinking about what a 3-line diagram would look like for this
operon, answer the following questions. Write numeric answers only. For example, if your
answer is 6 promoters, write only 6.
1) How many promoters control the expression of these genes?
2) How many locations does RNA Polymerase bind to get full expression of these genes?
3) How many ribosome binding sites are needed for full protein expression?
4) How many start codons will be needed for full protein expression?
5) How many mRNA strands will be produced with full operon expression?
6) How many proteins will be produced with full protein expression?
1
For the following questions, describe the expression levels of the structural genes in the Trp operon under the conditions described.
In the absence of tryptophan, the structural genes will:[ Select ] ["No longer be expressed", "Be constantly expressed", "Be deleted from the operon"]
In the presence of tryptophan, the structural genes will:[ Select ] ["No longer be expressed", "Be constantly expressed", "Be deleted from the operon"]
In the absence of tryptophan and the promoter sequence was mutated such that the RNA polymerase can no longer bind, the structural genes will:[ Select ] ["No longer be expressed", "Be constantly expressed", "Be deleted from the operon"]
The diagram below represents a hypothetical operon in the bacterium E. coli. The operon consists
of two structural genes (A and B), which code for the enzymes “Aase" and "Base", respectively, and
also includes P (promoter) and O (operator) regions as shown.
A
В
When a certain compound (X) is added to the growth medium of E. coli, the separate enzymes
"Aase" and "Base" are both synthesized at a 50-fold higher rate than in the absence of X. (X has a
molecular weight of about 200.) Which of the following statements is true of the operon described
above?
The region of the A gene that codes for the carboxyl-terminal amino acid of “Aase" is near the left end of the
A gene.
The P region contains nucleotide sequences to which the RNA polymerase holoenzyme (including the o
subunit) binds specifically but which the core enzyme does not recognize.
The addition of X to the growth medium causes a repressor protein to bind tightly to the O region.
The mRNA copied from this operon will be covalently…
Chapter 16 Solutions
Concepts of Genetics (12th Edition)
Ch. 16 - Even though the lac Z, Y, and A structural genes...Ch. 16 - Predict the level of genetic activity of the lac...Ch. 16 - Prob. 1CSCh. 16 - Prob. 2CSCh. 16 - Prob. 3CSCh. 16 - HOW DO WE KNOW? In this chapter, we focused on the...Ch. 16 - Prob. 2PDQCh. 16 - Contrast positive versus negative control of gene...Ch. 16 - Contrast the role of the repressor in an inducible...Ch. 16 - For the lac genotypes shown in the following...
Ch. 16 - For the genotypes and conditions (lactose present...Ch. 16 - The locations of numerous lacI and lacIS mutations...Ch. 16 - Prob. 8PDQCh. 16 - Prob. 9PDQCh. 16 - Predict the effect on the inducibility of the lac...Ch. 16 - Erythritol, a natural sugar abundant in fruits and...Ch. 16 - Prob. 12PDQCh. 16 - Prob. 13PDQCh. 16 - Neelaredoxin is a 15-kDa protein that is a gene...Ch. 16 - The creation of milk products such as cheeses and...Ch. 16 - Both attenuation of the trp operon in E. coli and...Ch. 16 - Prob. 17PDQCh. 16 - Prob. 18ESPCh. 16 - In a theoretical operon, genes A, B, C, and D...Ch. 16 - A bacterial operon is responsible for the...Ch. 16 - A marine bacterium is isolated and shown to...Ch. 16 - Prob. 22ESPCh. 16 - Prob. 23ESP
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- The lactose operon in E. coli comprises two structural genes and three regulatory components.a.State the name of each structural gene and describe its function: b.) State the name of each regulatory component and describe its functionarrow_forwardA number of mutations affect the expression of the lac operon in E. coli. The genotypes of several E. coli strains are shown below. ("+" indicates a wild-type gene with normal function and "-" indicates a loss-of-function allele.) Please predict which of the following strains would have the lowest beta-galactosidase enzyme activity, when grown in the lactose medium. Orpt o* z* r* Orpt ot z* Y OrptoztY Orrotzr OrPotz*Yarrow_forwardSupply the words “off" or “on" in the blanks below: In an inducible operon, transcription is normally and must be turned In a repressible operon, transcription is normally and must be turned Briefly describe the overall function of the structural genes in the lac operon. Briefly describe the overall function of the structural genes in the trp operon. For the following descriptions of the bacterial lac operon, determine if lactose is present (P) or absent (A). The repressor is bound to the operator. The repressor is inactive. RNA polymerase transcribes the structural genes. Allolactose is bound to the repressor For the following descriptions of the bacterial trp operon, determine if tryptophan levels are high (H) or low (L). The repressor is bound to the operator. The repressor is inactive. RNA polymerase transcribes the structural genes. Tryptophan is bound to the repressor.arrow_forward
- The lac operon consists of three structural genes, lacZ, lacY and lacA that are transcribed as a single polycistronic mRNA. You are given a new strain of Escherichia coli with the following lac operon genotype: p+0°Z•Y*A +// P*O*Z*Y+ A- (i) Explain how the lac I gene affects gene expression. (ii) Explain the function of the lacP in the bacterial operon. (iii) Which part of the lac operon is cis-dominant? Explain.arrow_forwardFor the following questions, describe the expression levels of the structural genes in the Lac operon under the conditions described. In the absence of lactose, the structural genes will:[ Select ] ["No longer be expressed", "Be constantly expressed", "Be deleted from the operon"] In the presence of lactose, the structural genes will:[ Select ] ["No longer be expressed", "Be constantly expressed", "Be deleted from the operon"] In the absence of lactose and the promoter sequence was mutated such that the RNA polymerase can no longer bind, the structural genes will:[ Select ] ["No longer be expressed", "Be constantly expressed", "Be deleted from the operon"] In the presence of lactose and the promoter sequence was mutated such that the RNA polymerase can no longer bind, the structural genes will:[ Select ] ["No longer be expressed", "Be constantly expressed", "Be deleted from the operon"] In the absence of lactose and the lacI repressor gene is mutated such that the repressor protein…arrow_forwardThe trp operon in E. coli encodes enzymes essential for the biosynthesis of tryptophan. In the operon, trpR gene encodes the repressor. A trpR repressor cannot bind tryptophan. The trpO is the operator. trpA encodes the enzyme tryptophan synthetase. For the enzyme (A), indicate with a + or-whether or not it is made when there is tryptophan and when there is no tryptophan. Without Tryptophan With Tryptophan R'O A /R* O' A R'O' A/R* Oʻ A R*OA/R' O Aarrow_forward
- Bob determines that Red/pink protein is synthesized at much higher amounts than the Brown protein; Bob thinks that this is how the burger always is perfectly medium-rare (pink/red in the interior of the patty, with a small amount of brown at the burger’s surface). Bob also knows that R and B both are transcribed from the single operon. Briefly describe the biological mechanism allowing for accumulation of more R than B protein.arrow_forwardExplain the process of attenuation in the trp operon under the following conditions: (i) No tryptophan (ii) High tryptophan levelsarrow_forwardA strain of E. coli has the genotypes shown below at the lac operon, where I = regulator gene, P = promoter, O = operator, Z = βgalactosidase gene, and Y = permease gene. The superscript+ indicates a wild-type allele,c indicates a constitutive mutation, and− indicates a defective mutation. For each genotype, indicate whether the enzyme will be synthesized or not synthesized when lactose is present or absent by placing a + for synthesis occurring and a − for synthesis not occurring in the appropriate blank. Explain your reasoning for each answer.arrow_forward
- 1) The UR operon which is composed of sequences A, B, C, and D (which may or may not be genes of regulatory sequences), encodes enzymes 1 and 2. Mutations in sequences A, B, C, and D have the following effects listed in the table below. A plus sign (+) indicates that the enzyme is synthesized and a minus sign (-) indicates that the enzyme is not synthesize. Mutation in UR present UR absent Enzyme 1 Enzyme 2 Enzyme 1 Enzyme 2 sequence No Mutation + + A + B + + + + C + D A) Is the UR operon inducible or repressible? B) Indicate which sequence (A, B, C, or D) is part of the following components of the operon: a. Regulator gene b. Promoter c. Structural gene for Enzyme 1 d. Structural gene for Enzyme 2arrow_forwardIn 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 answerarrow_forwardThe diagram below represents the tryptophan operon with the trp leader mRNA transcript enlarged to represent the AUG translation start codon, two consecutive tryptophan amino acid codons (UGGUGG), and 4 regions (1, 2, 3, and 4) that base pair to form different hairpin-loop structures in the mRNA leader region. Suppose a mutant bacteria has region 3 of the trp operon attenuator region mutated so that it cannot base pair normally. Would the bacteria grow in the absence of the amino acid tryptophan? (hint: in order for bacteria to grow in absence of tryptophan it should be able to synthesize its own tryptophan) Leader region trpE trpD trpC trpB trpA DNA 5' 3' Transcription trp leader sequence MRNA AUG UGGUGG UUUUUU 1 2 3 (tryptophan codons) There is insufficient information to answer the question. Yes No O Oarrow_forward
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