Ap Chapter 18 Homework
DNA methylation is a mechanism used by eukaryotes to do what? facilitate the binding of DNA to intermediate filaments terminate transcription increase the rate of transcription inactivate genes cause apoptosis
inactivate genes
What molecule binds to promoters in bacteria and transcribes the coding regions of the genes? RNA polymerase A nucleotide DNA ligase DNA polymerase
RNA polymerase
Which of these is NOT a component of the lac operon? lactose-utilization genes only promoter only regulatory gene only operator only promoter and operator
regulatory gene only
Which of the following terms describes the DNA-protein complexes that look like beads on a string? View Available Hint(s) Nucleosome Histones 30-nanometer fiber Chromatin
Nucleosome
The operon model of the regulation of gene expression in bacteria was proposed by _____. Watson and Crick Franklin Darwin Jacob and Monod Mendel
Jacob and Monod
Which of these is a regulatory gene? A B C D E
D
Under which conditions are the lac structural genes expressed most efficiently? No glucose, high lactose No glucose, no lactose High glucose, no lactose High glucose, high lactose
No glucose, high lactose
Which of the following statements about a gene that shows maternal effect inheritance is true? View Available Hint(s) Offspring will show a mutant phenotype if the mother has a mutant genotype. Offspring will have a mutant phenotype if the father has a mutant genotype. Offspring will always show a mutant phenotype if they have a mutant genotype. Embryonic cells transcribe the gene.
Offspring will show a mutant phenotype if the mother has a mutant genotype.
All your cells contain proto-oncogenes, which can change into cancer-causing genes. Why do cells possess such potential time bombs? View Available Hint(s) Proto-oncogenes protect cells from infection by cancer-causing viruses. Cells produce proto-oncogenes as a by-product of mitosis. Proto-oncogenes are unavoidable environmental carcinogens. Proto-oncogenes are necessary for the normal control of cell growth and division. Proto-oncogenes are genetic junk that has not yet been eliminated by natural selection
Proto-oncogenes are necessary for the normal control of cell growth and division.
Can you match terms related to operons to their definitions? Drag the terms on the left to the appropriate blanks on the right to complete the sentences.
1. A(n) operon is a stretch of DNA consisting of an operator, a promoter, and genes for a related set of proteins, usually making up an entire metabolic pathway. 2. The genes of an operon is/are arranged sequentially after the promoter. 3. A(n) promoter is a specific nucleotide sequence in DNA that binds RNA polymerase, positioning it to start transcribing RNA at the appropriate place. 4. A(n) regulatory gene codes for a protein, such as a repressor, that controls the transcription of another gene or group of genes. 5. Regulatory proteins bind to the operator to control expression of the operon. 6. A(n) repressoris a protein that inhibits gene transcription. In prokaryotes, this protein binds to the DNA in or near the promoter. 7. A(n) inducer is a specific small molecule that binds to a bacterial regulatory protein and changes its shape so that it cannot bind to an operator, thus switching an operon on.
Which of the following events in transcription initiation likely occurs last? View Available Hint(s) Regulatory transcription factors bind to enhancers. RNA polymerase binds to the promoter of the gene. TBP is recruited to the promoter. Basal transcription factors form a basal transcription complex.
RNA polymerase binds to the promoter of the gene.
What is the function of a spliceosome? protein activation translation protein degradation regulating the transport of mRNA to the cytoplasm RNA processing
RNA processing
Enzyme complexes that break down protein are called _____. lipases ubiquitins amylase proteasomes nucleases
proteasomes
Which of these indicates an enhancer region? A B C D C and D
A
Which statement(s) about repressible operons is/are correct? Select all that apply. A repressible operon is on unless a corepressor is present. Repressible operons usually contain genes that code for anabolic enzymes. In a repressible operon, the repressor is synthesized in an active form.
A repressible operon is on unless a corepressor is present. Repressible operons usually contain genes that code for anabolic enzymes.
The diagram below shows a segment of DNA containing an imaginary gene (Z) and the primary RNA transcript that results from the transcription of gene Z. Exons are represented in green and introns are represented in blue. Which of the following choices represent mRNA molecules that could be produced from the primary RNA transcript by alternative RNA splicing? (In each choice, the yellow part on the left represents the 5' cap, and the yellow part on the right represents the poly-A tail.)
ACEGI ACGI ACEI
Which body part develops in regions with a low concentration of Bicoid protein? View Available Hint(s) Abdomen Thorax Head
Abdomen
Which of the following regulatory elements is not composed of DNA sequences? View Available Hint(s) Enhancers Silencers Promoter-proximal elements Activators
Activators
_____ bind(s) to DNA enhancer regions. RNA polymerase Promoters Introns Activators Exons
Activators
Which of the following enzymes converts ATP to cAMP? Adenylyl cyclase b-galactosidase Galactoside permease ATP synthase
Adenylyl cyclase
Do the data suggest that any of these possible control elements are actual control elements? Only control element 3 appears to be a control element. Only control elements 1 and 2 appear to be control elements. All three appear to be control elements. None of the possible control elements appear to be actual control elements.
All three appear to be control elements
Which of the following statements best defines the term operon? An operon is a region of DNA that codes for a series of functionally related genes under the control of the same promoter. An operon is a region of DNA that codes for sugar-metabolizing enzymes. An operon is a region of RNA that consists of the coding regions of more than one gene. An operon is a region of DNA that consists of a single gene regulated by more than one promoter.
An operon is a region of DNA that codes for a series of functionally related genes under the control of the same promoter.
Which of the following is not a body segment of the fruit fly embryo? Antenna Thorax Abdomen Head
Antenna
Which of these directly bind(s) to the promoter? A B C D C and D
C and D
Did deletion of any of the possible control elements cause an increase in reporter gene expression? How can you tell? All of the deletions caused an increase in reporter gene expression; all of them still resulted in reporter mRNA being made. Deletion of control element #3 caused an increase in reporter gene expression; that construct resulted in less reporter mRNA than the control. Deletion of control element #1 or #2 caused an increase in reporter gene expression; both constructs resulted in over 100% of the control level of mRNA. Deletion of control element #1 caused an increase in reporter gene expression; that construct resulted in the highest level of mRNA.
Deletion of control element #1 or #2 caused an increase in reporter gene expression; both constructs resulted in over 100% of the control level of mRNA.
Did deletion of any of the possible control elements cause a reduction in reporter gene expression? How can you tell? Deletion of element #3 caused a reduction in reporter gene expression; that construct resulted in less than 50% of the control level of mRNA. Deletion of elements #2 and #3 caused a reduction in reporter gene expression; those constructs resulted in less than the highest level of mRNA. None of the deletions caused a reduction in reporter gene expression; all of them still resulted in reporter mRNA being made.
Deletion of element #3 caused a reduction in reporter gene expression; that construct resulted in less than 50% of the control level of mRNA.
Which of the following regulatory DNA sequences might be located thousands of nucleotides away from the transcription start site of a gene? View Available Hint(s) Promoter-proximal element TATA box Enhancer Promoter
Enhancer
True or false? One possible way to alter chromatin structure such that genes could be transcribed would be to make histone proteins more positively charged. View Available Hint(s) True False
False
True or false? Regulatory and basal transcription factors regulate transcription by binding to the promoter. View Available Hint(s) True False
False
True or false? The mechanism by which glucose inhibits expression of the lac structural genes is known as catabolite stimulation, whereas the mechanism by which lactose stimulates expression of the lac structural genes is known as allosteric regulation. View Available Hint(s) True False
False
Where is bicoid mRNA translated? View Available Hint(s) Fertilized egg Nurse cells Follicle cells Sperm cells
Fertilized egg
What is allosteric regulation? In allosteric regulation, a gene is turned on by an activator protein. In allosteric regulation, genes are expressed constitutively. In allosteric regulation, a small molecule binds to a large protein and causes it to change its shape and activity. In allosteric regulation, a gene is turned off by a repressor protein.
In allosteric regulation, a small molecule binds to a large protein and causes it to change its shape and activity.
Which statement(s) about inducible operons is/are correct? Select all that apply. In an inducible operon, an inducer inactivates the repressor. Inducible enzymes generally function in synthetic pathways that produce end products from raw materials. In an inducible operon, the repressor is synthesized in an active form.
In an inducible operon, an inducer inactivates the repressor. In an inducible operon, the repressor is synthesized in an active form.
You are studying a bacterium that utilizes a sugar called athelose. This sugar can be used as an energy source when necessary. Metabolism of athelose is controlled by the ath operon. The genes of the ath operon code for the enzymes necessary to use athelose as an energy source. You have found the following: The genes of the ath operon are expressed only when the concentration of athelose in the bacterium is high. When glucose is absent, the bacterium needs to metabolize athelose as an energy source as much as possible. The same catabolite activator protein (CAP) involved with the lac operon interacts with the ath operon. Based on this information, how is the ath operon most likely controlled? Drag the labels onto the diagram to identify the small molecules and the states of the regulatory proteins. Not all labels will be used.
Positive control: Inactive activator, cAMP, Active activator Negative control: Active repressor, athelose, inactive repressor
Which statements about the modification of chromatin structure in eukaryotes are true? Select all that apply. View Available Hint(s) Some forms of chromatin modification can be passed on to future generations of cells. Methylation of histone tails in chromatin can promote condensation of the chromatin. Acetylation of histone tails in chromatin allows access to DNA for transcription. Deacetylation of histone tails in chromatin loosens the association between nucleosomes and DNA. Acetylation of histone tails is a reversible process. DNA is not transcribed when chromatin is packaged tightly in a condensed form.
Some forms of chromatin modification can be passed on to future generations of cells. Methylation of histone tails in chromatin can promote condensation of the chromatin. Acetylation of histone tails in chromatin allows access to DNA for transcription. Acetylation of histone tails is a reversible process. DNA is not transcribed when chromatin is packaged tightly in a condensed form.
Which of the following statements about the Bicoid protein is true? View Available Hint(s) The Bicoid protein is a cytoplasmic determinant. The Bicoid protein is diffused evenly throughout the fertilized egg. The Bicoid protein is a regulatory transcription factor. The Bicoid protein establishes the dorsal-ventral body axis.
The Bicoid protein is a regulatory transcription factor.
Which statements about the regulation of transcription initiation in these genes are true? Select all that apply. View Available Hint(s) The fantasin gene and the imaginin gene have identical enhancers. Both the fantasin gene and the imaginin gene will be transcribed at high levels whenever general transcription factors are present in the cell. The fantasin gene will be transcribed at a high level when activators specific for control elements A, B, and C are present in the cell. The imaginin gene will be transcribed at a high level when repressors specific for the imaginin gene are present in the cell. Control elements A, B, and C are proximal control elements for the fantasin gene. Both the fantasin gene and the imaginin gene will be transcribed at high levels when activators specific for control elements A, B, C, D, and E are present in the cell. Control elements C, D, and E are distal control elements for the imaginin gene.
The fantasin gene will be transcribed at a high level when activators specific for control elements A, B, and C are present in the cell. Both the fantasin gene and the imaginin gene will be transcribed at high levels when activators specific for control elements A, B, C, D, and E are present in the cell. Control elements C, D, and E are distal control elements for the imaginin gene.
If bicoid mRNA is injected at the anterior end of an egg from a bicoid mutant mother, what would the phenotype of the resulting larva be? View Available Hint(s) The larva would be normal with one head at the anterior pole. The larva would have two heads, one at the anterior pole and one in the middle of its body. The larva would have a head at each pole of its body. The larva would be normal with one head at the posterior pole.
The larva would be normal with one head at the anterior pole.
What happens to the expression of the lacI gene if lactose is not available in the cell? The lacI gene turns off. The lacI gene turns on. There is no change—the lacI gene is constitutively expressed. The lacI gene increases its rate of transcription.
There is no change—the lacI gene is constitutively expressed
What is the function of the lacZ gene? This gene encodes an enzyme, b-galactosidase, that cleaves lactose into two glucose molecules. This gene encodes an enzyme, galactoside permease, which transports lactose into the cell. This gene encodes the repressor of the lac operon. This gene encodes an enzyme, b-galactosidase, which cleaves lactose into glucose and galactose.
This gene encodes an enzyme, b-galactosidase, which cleaves lactose into glucose and galactose.
If deletion of a control element causes a reduction in gene expression, what must be the normal role of that control element? To activate gene expression; without the control element, repressors are not able to bind to the enhancer, and the level of gene expression increases. To repress gene expression; without the control element, repressors are not able to bind to the enhancer, and the level of gene expression decreases. To activate gene expression; without the control element, activators are not able to bind to the enhancer, and the level of gene expression decreases. To repress gene expression; without the control element, repressors are not able to bind to the enhancer, and the level of gene expression increases.
To activate gene expression; without the control element, activators are not able to bind to the enhancer, and the level of gene expression decreases.
If deletion of a control element causes an increase in gene expression, what must be the normal role of that control element? To repress gene expression; without the control element, activators are not able to bind to the enhancer, and the level of gene expression decreases. To repress gene expression; without the control element, repressors are not able to bind to the enhancer, and the level of gene expression increases.T o activate gene expression; without the control element, activators are not able to bind to the enhancer, and the level of gene expression decreases. To activate gene expression; without the control element, repressors are not able to bind to the enhancer, and the level of gene expression increases.
To repress gene expression; without the control element, repressors are not able to bind to the enhancer, and the level of gene expression increases.
True or False? Pattern formation refers to events that organize embryonic cells in space View Available Hint(s) True False
True
Why is the lac operon said to be an inducible operon? When allolactose is present, it induces the activation of the lac repressor. When activated, the lac operon induces the production of lactose-digesting enzymes. When activated, the lac operon induces repression of gene expression. When allolactose is present, it induces the inactivation of the lac repressor. When allolactose is present, it induces repression of gene expression.
When allolactose is present, it induces the inactivation of the lac repressor.
A lack of which molecule would result in a cell's inability to "turn off" genes? operon inducer promoter corepressor
corepressor
miRNAs can control gene expression by what action? View Available Hint(s) binding to DNA and preventing transcription of certain genes seeking out viral DNA and destroying it degrading proteins as soon as they are formed binding to mRNAs and degrading them or blocking their translation inhibiting the catalytic activity of rRNA
binding to mRNAs and degrading them or blocking their translation
In the presence of a regulatory protein the lac operon is _____. transcribed not transcribed transcribed at a faster than usual rate is turned on either transcribed or not transcribed
not transcribed
The trp and lac operons are regulated in various ways. How do bacteria regulate transcription of these operons? Sort the statements into the appropriate bins depending on whether or not each operon would be transcribed under the stated conditions.
operon is not transcribed lac operon: lactose absent trp operon: tryptophan present operon is transcribed, but not sped up through positive control trp operon: tryptophan absent lac operon: lactose present,glucose present operon is transcribed quickly through positive control lac operon: lactose present,glucose absent
Protein-phosphorylating enzymes' role in the regulation of gene expression involves _____. protein activation translation protein degradation regulating the transport of mRNA to the cytoplasm RNA processing
protein activation
The nuclear membrane's role in the regulation of gene expression involves _____. protein activation translation protein degradation regulating the transport of mRNA to the cytoplasm RNA processing
regulating the transport of mRNA to the cytoplasm
What was the control treatment in this experiment? the construct that resulted in the lowest amount of reporter mRNA the construct that had no DNA deleted from the enhancer the reporter gene the temperature, pH and salt concentration of the incubation medium
the construct that had no DNA deleted from the enhancer
The lactose operon is likely to be transcribed when _____. there is more glucose in the cell than lactose the cAMP level is high and the lactose level is low the cyclic AMP and lactose levels are both high within the cell there is glucose but no lactose in the cell
the cyclic AMP and lactose levels are both high within the cell
Regulatory proteins bind to _____. the operator the lactose-utilization genes the regulatory gene RNA polymerase transcription factors
the operator
The diagrams show the intact DNA sequence (top) and the three experimental DNA sequences. A red X indicates the possible control element (1, 2, or 3) that was deleted in each experimental DNA sequence. The area between the slashes represents the approximately 8 kilobases of DNA located between the promoter and the enhancer region. The horizontal bar graph shows the amount of reporter gene mRNA that was present in each cell culture after 48 hours relative to the amount that was in the culture containing the intact enhancer region (top bar = 100%). What was the independent variable in this experiment? the distance between the promoter and the enhancer the length of time that the cells were incubated the possible control element that was deleted the relative level of reporter gene mRNA
the possible control element that was deleted
What was the dependent variable in this experiment? how many of the artificial DNA molecules were taken up by the cells the length of time that the cells were incubated the distance between the promoter and the enhancer the relative level of reporter gene mRNA
the relative level of reporter gene mRNA
