BS161 Exam 4
Acetylation changes the charge on lysine from: +1 to +1 0 to -1 +1 to -1 +1 to 0 0 to +1 NOTE: image 2
+1 to 0
After replication, maintenance methylase would methylate which cytosine(s). 3 4 1 and 2 all 3 and 4 NOTE: image 1
4
Which is a housekeeping gene? M cyclin, which is only expressed during M phase The sodium-glucose transporter, which moves glucose into cells in the kidney ATP synthase, which produces ATP in mitochondria Hemoglobin, which carries oxygen in red blood cells
ATP synthase, which produces ATP in mitochondria
Which of these would you classify as a housekeeping gene? The gene encoding: (select all correct answers) ATP synthase. DNA polymerase. RNA polymerase. the insulin peptide.
ATP synthase. RNA polymerase.
Match the protein(s) with their function. Activators and repressors: RNA polymerase: General transcription factors: bind to the promoter and recruit RNA polymerase. uses the DNA template to produce mRNA. are usually expressed in a small number of cell types.
Activators and repressors: are usually expressed in a small number of cell type RNA polymerase: uses the DNA template to produce mRNA. General transcription factors: bind to the promoter and recruit RNA polymerase.
How would the graph differ in a bacterium in which the operator was removed but all other aspects of the DNA remain the same? lacZ mRNA will start high and remain high. lacZ mRNA will start high but will steadily decrease over time. lacZ mRNA will always remain low. After lacZ mRNA levels peak, they will remain constant because the LacI repressor cannot bind to the DNA and prevent transcription. NOTE: image 10
After lacZ mRNA levels peak, they will remain constant because the LacI repressor cannot bind to the DNA and prevent transcription.
Galactose increases the transcription of five genes by roughly a 1000-fold. The genes are monocistronic and on different chromosomes. How is gene expression coordinated? All five genes have promoters that bind the same general transcription factors. Each gene binds different general transcription factors at the promoter region. All five genes have enhancers that bind the same type of activator. Each gene has a unique enhancer that binds a different activator.
All five genes have enhancers that bind the same type of activator.
G3PDH is an enzyme needed for glycolysis, while lactase is an enzyme required to digest the sugar lactose. The figure shows mRNA from these genes in mice at different ages. Which is a reasonable argument based on these data? Over time, the amount of lactase enzyme in mice increases because lactase gene expression increases over time. At four weeks, mice can break down glucose, but not lactose, because G3PDH mRNA is present, but lactase mRNA is absent. Over time, the amount of G3PDH enzyme in mice increases because G3PDH gene expression increases over time. At four weeks, mice can use lactase to break down lactose because mice express the lactase gene. NOTE: image 3
At four weeks, mice can break down glucose, but not lactose, because G3PDH mRNA is present, but lactase mRNA is absent.
Which statement is false. cAMP increases the affinity of CAP for the CAP-binding site. CAP is a repressor. cAMP binding changes the shape (conformation) of CAP. The binding of CAP / CRP (i.e., Catabolic Activator Protein or cAMP receptor protein) to the promoter increases transcription.
CAP is a repressor.
What happens between regions A and B on the X axis that cause levels of lacZ mRNA to increase? LacI is released from the operator CRP/CAP is released from the CRB binding site LacI binds to the operator CRP/CAP to binds to CRB binding site NOTE: image 10
CRP/CAP to binds to CRB binding site
Cell 1 contains membrane proteins with type A and type B sugars. Cell 2 lacks these sugars. What is true for Cell 2? Cell 2 does not produce the enzyme that adds these sugars to the surface of red blood cells. Cell 2 produces only the A allele of the protein that adds sugars to the surface of red blood cells. More information is needed to answer this question. Cell 2 produces both the A and B alleles of the protein that adds sugars to the surface of red blood cells. NOTE: image 15
Cell 2 does not produce the enzyme that adds these sugars to the surface of red blood cells.
The paper primarily addresses which major challenge in the treatment of diabetes. It is difficult for most people to consistently maintain a normal blood glucose level because of the challenges involved in following a healthy diet. Organ transplantation is severely limited by the small percentage of people willing to donate their organs. Converting embryonic stem cells into β-cells has met with limited success using conventional approaches.
Converting embryonic stem cells into β-cells has met with limited success using conventional approaches.
How do different cell types in a single organism arise? DNA sequences in different cells are virtually identical, but the RNA and protein sequences differ. DNA and RNA sequences in different cells are virtually identical, but proteins differ. DNA, RNA, and protein sequences all differ significantly between cell types.
DNA sequences in different cells are virtually identical, but the RNA and protein sequences differ.
A mutation in the regulatory region of a gene causes a positive transcription factor to bind more tightly to the DNA. What will likely happen and why? Expression of this gene will decrease because mutations in regulatory regions of genes prevent RNA polymerase from initiating transcription. Expression of this gene will change in unpredictable ways because mutations are random and their effects are unpredictable. Expression of this gene will decrease because it will now require a different positive transcription factor as the result of the mutation. Expression of this gene will increase because the positive transcription factor will cause RNA polymerase to transcribe the gene more frequently.
Expression of this gene will increase because the positive transcription factor will cause RNA polymerase to transcribe the gene more frequently.
Epigenetic modifications, once inherited, are permanent and will always be passed down to offspring. True False
False
Heterochromatin is easily accessible DNA, and is the most common DNA form where genes must be expressed. (If you don't know for certain, look to your notes.) True False
False
The CpG sites located near the promoter regions of all genes are methylated. True False
False
True/False: Cells that express the activator for the pluripotency gene (OCT-4) do not synthesize the OCT-4 protein. True False
False
A frameshift mutation early in gene B would most likely harm protein production for which gene(s)? Gene B and C Gene B Gene A Gene B, C, and D NOTE: image 9
Gene B
The graph shows lacI and lacZ mRNA over time. Initially, glucose and lactose are present. What happens during A that causes increasing lacZ mRNA during B? Glucose catabolism decreases the amount of glucose present. Lactose catabolism decreases the amount of lactose present. NOTE: image 10
Glucose catabolism decreases the amount of glucose present.
Suppose a person has allele A for the glycosyltransferase that adds sugars to red blood cells on one homologous chromosome and allele B on the other. What is true about the amino acid sequence for the glycosyltransferase proteins found in their cells? Half of the glycosyltransferase proteins will have one amino acid sequence and the other half of the glycosyltransferase proteins will have a different amino acid sequence. All of the glycosyltransferase proteins will have the same amino acid sequence.
Half of the glycosyltransferase proteins will have one amino acid sequence and the other half of the glycosyltransferase proteins will have a different amino acid sequence.
Which change in the gene expression process would likely decrease the amount of protein produced? Increasing the concentration of a negative transcription factor. Remodeling the chromatin in a way that makes the DNA more accessible. Increasing the stability of the mRNA. Increasing the affinity of the promoter for RNA polymerase. Increasing the affinity of a positive transcription factor for an enhancer.
Increasing the concentration of a negative transcription factor.
Which of the following is necessary for high levels of expression of the lac operon? Low levels of glucose Low levels of cAMP Low levels of lactose LacI binding to the operator
Low levels of glucose
If splicing occurred at d1-a1 + d2-a2 + d3-a3, what protein would result? MHL ML MKL MHKL NOTE: image 6
MHKL
If splicing occurred at d1-a2 + d3-a3, what protein would result? MHKL MKL MHL ML NOTE: image 6
MKL
What combination will result in the most accessible form of DNA? More histone acetylation, less DNA methylation More histone acetylation, more DNA methylation Less histone acetylation, less DNA methylation More histone acetylation, more DNA methylation
More histone acetylation, less DNA methylation
Based on the chemical structure of DNA, what is the net charge? Negative Neutral Positive NOTE: image 5
Negative
What is the net charge of a double stranded DNA molecule? Neutral Positive Negative
Negative
The figure shows a model of a gene. The open reading frame that encodes the protein is shaded in gray. The start codon is in the middle of Exon 1 and the stop codon is in the middle of Exon 3. The white regions show the 5'UTR and 3'UTR regions. If a mutation occurs in Exon 4, will it change the sequence of the protein? Why or why not? No, a mutation in Exon 4 will not change the protein sequence because this region of the gene is not translated. Yes, a mutation in Exon 4 will change the protein sequence, because it will inhibit transcription. Yes, a mutation in Exon 4 will change the protein sequence, because all regions of all exons are translated into proteins. No, a mutation in Exon 4 will not change the protein sequence because it is removed through alternative splicing. NOTE: image 11
No, a mutation in Exon 4 will not change the protein sequence because this region of the gene is not translated
A mutation occurs in the 5' UTR (5' untranslated region) of a gene. The top strand is the sense strand and the bottom strand is the template. Will the mutation change the length of the protein? Yes, the protein will be longer because the mutation occurs in the 5' UTR and creates a new start codon. No, because the mutation occurs in the 5' UTR and does not create a start codon, the length of the protein will not change. NOTE: image 12
No, because the mutation occurs in the 5' UTR and does not create a start codon, the length of the protein will not change.
A specific sequence of DNA that a prokaryotic repressor can bind to is called an: Poly(A) tail TATA box Promoter Operator
Operator
In the image, the same-colored bands correspond to the same genes on the chromosomes. A person has both A and O blood type alleles. If position 1 indicates the A allele, what do you know about the sequence at the other positions? Position 2 must be an O allele. Position 2 must be an A allele. Position 3 must be an A allele. Position 4 must be an 0 allele. NOTE: image 14
Position 2 must be an A allele.
In the image, the same-colored bands correspond to the same genes on the chromosomes. A person has both A and O blood type alleles. If position 1 indicates the A allele, what do you know about the sequence at the other positions? Position 2 must be the O allele. Position 3 must be the A allele. Position 4 must be the A allele. Position 5 must be the O allele. NOTE: image 14
Position 5 must be the O allele.
G3PDH is an enzyme needed for glycolysis, while lactase is an enzyme required to digest the sugar lactose. This figure shows the mRNA from these genes in different tissues in mice. What is a reasonable explanation for observation that lactase is expressed in only some cell types? The lactase gene is spliced out of DNA in most, but not all cell types. Enzymes that degrade the lactase protein are found at a high concentration, in most, but all cell types. Positive transcription factors bind to the regulatory regions of the lactase gene in some cell types but not others. The lactase gene promoter is present in some cells but not others. NOTE: image 4
Positive transcription factors bind to the regulatory regions of the lactase gene in some cell types but not others.
What is the difference between the primary and the processed RNA transcripts? Primary transcripts include introns. Primary transcripts exclude exons. Processed transcripts are proteins that exclude introns. Processed transcripts include introns.
Primary transcripts include introns.
Small regulatory RNAs work in conjunction with: ribosomal RNA. RNA polymerase. nucleosomes. RISC proteins.
RISC proteins.
Match the answers Activator/Specific Transcription Factor RNA Polymerase Enhancer Promoter General Transcription Factors an enzyme that makes an RNA copy of the coding region
RNA Polymerase: an enzyme that makes an RNA copy of the coding region Enhancer: a DNA sequence to which an activator can bind Activator/Specific Transcription Factor: a protein whose binding is gene-specific General Transcription Factors: proteins that help RNA polymerase to bind at a promoter Promoter: a DNA sequence to which general transcription factors bind
What is present in cells where the transcription of a unique gene, like the sodium-glucose transporter, occurs compared to cells where the unique gene is not transcribed? Specific transcription factors for the gene General transcription factors for the gene Repressor molecules for the gene DNA promoter sequences for the gene
Specific transcription factors for the gene
Suppose we examine gene expression in an adult pancreatic beta cell. Which genes would be the most likely expressed? (Select all). The neurotransmitter TPH1 gene The ATP synthase MT-ATP6 gene The INS gene that makes the hormone insulin The OCT-4 gene, which is needed for stem cells
The ATP synthase MT-ATP6 gene The INS gene that makes the hormone insulin
Why does acetylation lead to less condensed chromosomes? The acetyl group increases the negative charge on histone groups. The acetyl group directly inhibits the enzyme responsible for histone production, leading to less histone binding to DNA. The acetyl group increases the positive charge on histone groups, leading to less histone binding to DNA. The acetyl group decreases the positive charge on histone groups.
The acetyl group decreases the positive charge on histone groups.
What occurs in positive transcriptional regulation to result in transcription? (Hint: Is there a difference between a promoter and the activator binding site? See text book and notes if you are not sure.) The activator protein binds to the promoter region The repressor protein binds to the promoter region The activator protein binds to the activator binding site The repressor protein binds to the activator binding site
The activator protein binds to the activator binding site
G3PDH is an enzyme needed for glycolysis, while lactase is an enzyme needed to digest the sugar lactose. The figure shows mRNA from these genes in mice at different ages. What do the data show? Hint: The dark lines are related to the amount of mRNA for G3PDH and Lactase at 1, 2, and 4 weeks of age. The darker the line, the greater the amount of RNA. If the darkness of a line decreases, the amount of mRNA decreases. The amount of G3PDH mRNA decreases, while the amount of lactase mRNA remains constant as mice mature. The amount of lactase mRNA increases, while the amount of G3PDH decreases as mice mature. The amount of lactase mRNA decreases, while the amount of G3PDH mRNA remains constant as mice mature. The amount of both lactase and G3PDH mRNA remains constant as mice mature. NOTE: image 3
The amount of lactase mRNA decreases, while the amount of G3PDH mRNA remains constant as mice mature.
Why do Calico cats have their unique pattern of coloring? The coloration pattern arises due to the random inactivation of one of their X chromosomes. The coloration pattern arises due to the random inactivation of one of their Y chromosomes. Scientists have yet to understand this process. Calico cats only have one X chromosome, compared to normal cats that have two X chromosomes.
The coloration pattern arises due to the random inactivation of one of their X chromosomes.
The pluripotency gene OCT-4 promotes the indefinite division of stem cells. If a frameshift mutation occurs early in the gene's coding region, one would expect that the protein's function would be disrupted. How would such a mutation change the level of expression of the mRNA encoding the mutant gene? The frameshift mutation would reduce the amount of OCT-4 mRNA production. More information is required to answer the question. The frameshift mutation would increase the amount of OCT-4 mRNA production. The frameshift mutation would not affect the amount of OCT-4 mRNA production.
The frameshift mutation would not affect the amount of OCT-4 mRNA production.
Which statement about LacI and the lac operon is correct? (Hint: Are the promoter and operator the same?) LacI can bind to the promoter region of the lac operon LacI is the only protein involved in the regulation of the lac operon LacI is active and binds to the lac operator when lactose is present The lac operon transcription is reduced when LacI binds to DNA
The lac operon transcription is reduced when LacI binds to DNA
This is Figure 18.15 in the textbook. Based on the figure, reading in the textbook, and the lecture notes, select all of the correct statements. The lacZ coding sequence for β-galactosidase and lacY coding sequence for lactose permease are genes called structural genes. The promoter sequence recruits RNA polymerase complex and the initiation of transcription. lacI is a gene sequence coding for the repressor which binds to the operator, inhibiting transcription. The CRP-cAMP binding site promotes transcription of lactose operon genes if cAMP is high, which indicates that glucose is low and lactose metabolism is needed for energy production. NOTE: image 8
The lacZ coding sequence for β-galactosidase and lacY coding sequence for lactose permease are genes called structural genes. The promoter sequence recruits RNA polymerase complex and the initiation of transcription. lacI is a gene sequence coding for the repressor which binds to the operator, inhibiting transcription. The CRP-cAMP binding site promotes transcription of lactose operon genes if cAMP is high, which indicates that glucose is low and lactose metabolism is needed for energy production.
G3PDH is an enzyme needed for glycolysis, while lactase is an enzyme required to digest the sugar lactose. This figure shows the mRNA from these genes in mice at different ages. What is a reasonable explanation for why lactase gene expression decreases over time? The amount of RNA polymerase available to produce mRNA decreases over time. The number of lactase enhancer sequences present in the DNA in each mouse cell decreases over time. The level of a positive transcription factor that binds to the lactase regulatory region decreases over time. The number of lactase genes found in each mouse cell decreases over time. NOTE: image 3
The level of a positive transcription factor that binds to the lactase regulatory region decreases over time.
What causes cells in the early embryo to differentiate into a specific cell type ? The DNA for unneed genes is deleted after implantation into the uterus using srRNAs. Each specific cell type expresses a subset of general transcription factors to drive differentation. The presence of cell type specific transcription factors called activators causes a cell to differentitate into a specific cell type.
The presence of cell type specific transcription factors called activators causes a cell to differentitate into a specific cell type.
What is true of positive transcription factors? They bind to regulatory regions in the DNA and allow the ribosome to transcribe genes. They bind to the 5' UTR of mRNA and allow RNA polymerase to translate that mRNA. They bind to regulatory regions in the DNA and allow RNA polymerase to transcribe genes. They bind to the 5' UTR of mRNA and allow the ribosome to translate that mRNA.
They bind to regulatory regions in the DNA and allow RNA polymerase to transcribe genes.
The binding of a regulatory molecule to an operon blocks the transcription process. Which of the following statements is correct? This molecule functions as an activator This is an example of positive regulation This molecule binds to the promoter region This molecule functions as a repressor
This molecule functions as a repressor
A frameshift mutation occurs in the second intron. How will this alter DNA replication, transcription, and translation? (Select all correct answers.) This will reduce translation. This will reduce transcription. This will reduce DNA replication. This will have no effect on replication, transcription, or translation.
This will have no effect on replication, transcription, or translation.
A nonsense mutation occurs in the second exon. How will this alter DNA replication, transcription, and translation? (Select all correct answers.) This will reduce translation by creating a shorter protein. This will reduce DNA replication. This will reduce transcription. This will have no effect on replication, transcription, or translation.
This will reduce translation by creating a shorter protein.
A missense mutation occurs in the start codon. How will this alter DNA replication, transcription, and translation? (Select all correct answers.) This will reduce transcription. This will reduce translation This will have no effect on replication, transcription, or translation. This will reduce DNA replication.
This will reduce translation.
A mutation in the promoter reduces RNA polymerase activity. How will this alter DNA replication, transcription, and translation? (Select all correct answers.) This will reduce translation. This will reduce transcription. This will reduce DNA replication. This will have no effect on replication, transcription, or translation.
This will reduce translation. This will reduce transcription.
In both prokaryotic and eukaryotic gene expression, Transcription requires RNA polymerase binding to promoter regions One type of RNA corresponds to only one type of protein RNA must be transported out of the nucleus for translation Introns are removed from genes before translation
Transcription requires RNA polymerase binding to promoter regions
Gene regulation in multicellular organisms leads to differential gene expression and specialized cell functions. True False
True
Gene regulation is influenced by both genetic and environmental factors. True False
True
What fraction of genes are expressed in a typical human cell? Only 1% of genes present in a cell's DNA are expressed. Twenty-five percent of the genes present in a cell's DNA are expressed. All of the genes present in a cell's DNA are expressed. Fifty percent of the genes present in a cell's DNA are expressed.
Twenty-five percent of the genes present in a cell's DNA are expressed.
The diagram represents a generic DNA sequence in a prokaryotic cell with the sequence features indicated. Which statement is correct? When expressed, this operon will produce four different polypeptides When expressed, this operon will produce three different mRNAs When expressed, this operon will produce three different polypeptides Genes A, B, and C are regulated by different promoters and operators NOTE: image 7
When expressed, this operon will produce three different polypeptides
In female humans and other mammals, dosage compensation is achieved by the inactivation of one of the two X chromosomes in each cell. Which one of the following does not occur in the X-inactivation mechanism of female mammals? (Hint: See book for more details.) When an X chromosome is about to be inactivated, Xist RNA transcripts increase markedly and undergo splicing, but do not encode a protein. Xist RNA recruits factors that promote DNA methylation, histone modification, and other changes associated with transcriptional silencing. X-inactivation begins with a small region of the X chromosome that contains a gene for an X-inactivation specific transcript (Xist). Xist RNA produces the Xist protein. This protein coats one of the two X chromosomes in females and inactivates it by increasing the association of histones with DNA.
Xist RNA produces the Xist protein. This protein coats one of the two X chromosomes in females and inactivates it by increasing the association of histones with DNA.
Is the gene for the synthesis of the neurotransmitter serotonin (TPH1) found in pancreatic beta cells? Yes, every somatic cell contains all the genes of that organism. No, the TPH1 gene produces a neurotransmitter only in neurons, thus it is absent in pancreatic beta cells.
Yes, every somatic cell contains all the genes of that organism.
A mutation occurs in the 5' UTR (5' untranslated region) of a gene. The top strand is the sense strand and the bottom strand is the template. Will the mutation change the length of the protein? No, because the mutation occurs in the 5' UTR and does not create a start codon, the length of the protein will not change. Yes, the protein will be shorter because the mutation creates a new stop codon. No, even though the mutation creates a stop codon in the 5'UTR because the mutation is after a pre-existing stop codon, ribosomes will never reach it. Yes, the protein will be a different length because the mutation occurs in the 5' UTR and creates a new start codon. NOTE: image 13
Yes, the protein will be a different length because the mutation occurs in the 5' UTR and creates a new start codon.
Combinatorial control refers to a regulatory mechanism in which: a combination of sites in the terminator halts transcription. each alternatively spliced transcript has a different combination of exons. a combination of sites in the promoter initiate transcription. a specific combination of transcription factors influences gene expression.
a specific combination of transcription factors influences gene expression.
In prokaryotes, the AUG codon that starts translation is: adjacent to a Shine-Dalgarno sequence. the AUG nearest the 5' cap on the mRNA. at the 5' end of the mRNA. adjacent to the 5' cap on the mRNA.
adjacent to a Shine-Dalgarno sequence.
Alternative splicing regulates gene expression by: creating mutations in RNA. degrading specific domains in proteins. altering DNA sequences in chromosomes. altering mRNA sequences.
altering mRNA sequences.
Which process produces multiple proteins from the same primary transcript in the same cell? alternative splicing histone modification chromatin remodeling combinatorial control
alternative splicing
An activator protein combines with a small molecule and undergoes a change in shape that alters its binding affinity to DNA. This change in shape is an example of: an allosteric effect. dosage compensation. the activator effect. induced silencing. a position effect.
an allosteric effect.
Cellular differentiation progressively restricts cell fate because the unexpressed genes in the cell: accumulate near the centromeres. become more densely packed with histones to form nucleosomes. are deleted from the genome. accumulate point mutations.
become more densely packed with histones to form nucleosomes.
Bacteria with a mutation eliminating the function of the lacZ gene (lacZ -): (Hint: See textbook, if you are not sure what lacZ means.) can more easily cleave lactose into sugars cannot transport lactose into the cell cannot utilize lactose for energy can more efficiently utilize lactose for energy
cannot utilize lactose for energy
Which statement is most accurate? Cells in different tissue types contain different: DNA coding sequences. enhancer sequences. cell type specific transcription factors called activators. general transcription factors.
cell type specific transcription factors called activators.
In what order do the levels of gene regulation take place going from the highest to the lowest level over time? transcription post-translational modification RNA processing chromatin structure
chromatin structure transcription RNA processing post-translational modification
The diagram shown here is part of an RNA transcript containing four open reading frames (M, H, K, and L) and three introns (1, 2, 3). The sites labeled d1-d3 are nucleotides immediately before each intron on the 5' side and those labeled a1-a3 are nucleotides immediately after each intron on the 3' side. Splicing out an intron involves a spliceosome facilitating the cleavage of the DNA at the d and a sites at either end of the intron. A missense mutation takes place in open reading frame H. In which possible alternative splice forms of the transcript would the missense mutation not affect the polypeptide product? (Select all that apply.) d1-a1 + d2-a2 + d3-a3 d1-a2 + d3-a3 d1-a1 + d2-a3 d1-a3 NOTE: image 6
d1-a2 + d3-a3 d1-a3
Because DNA has a phosphodiester backbone, it has a net negative charge. Adding an acetyl group to the lysines in histone tails would: not affect effect on DNA binding. increase DNA binding. decrease DNA binding.
decrease DNA binding.
If the insulin gene (INS) promoter sequence has a mutation that does not allow RNA polymerase to bind, how will cellular glucose uptake be affected? The mutation will: decrease cellular glucose uptake because insulin induces the insertion of glucose transporters into the plasma membrane. increase cellular glucose uptake because decreased insulin levels cause blood sugar levels to rise. decrease cellular glucose uptake because it will decrease glucose transporter mRNA production, leading to less translation. not affect glucose uptake because the insulin gene does not make the proteins that import glucose into cells.
decrease cellular glucose uptake because insulin induces the insertion of glucose transporters into the plasma membrane.
If a mutation prevented a poly-A tail from being added to the processed mRNA this would: alter alternative splicing. have no effect on translation. change the sequence of the protein produced from the mRNA. decrease protein levels because mRNAs would be degraded.
decrease protein levels because mRNAs would be degraded.
Alternative splicing allows for: enhanced recognition of an mRNA by a ribosome. increased stability of a mature mRNA. different polypeptides to be made from a single gene. multiple genes to be used to code for a single polypeptide chain. two or more different proteins to be made from a single processed mRNA.
different polypeptides to be made from a single gene.
In messenger RNA, the protein-coding sequence is present in: introns. exons and the poly(A) sequence. introns and the poly(A) sequence. exons.
exons
The human body contains approximately 200 major cell types. They look and function differently from one another because each cell type: expresses a different set of genes. has a slightly different genome and each expresses a different set of genes. has a slightly different genome. expresses the same set of genes, but in different orders at different times.
expresses a different set of genes.
In mammals, dosage compensation occurs because: females decrease transcription of both X chromosomes by half. females lose one X chromosome from each cell. males transcribe X chromosome genes at twice the rate of females. females randomly inactivate one X chromosome in each cell. females inactivate the paternal X chromosome in each cell.
females randomly inactivate one X chromosome in each cell.
If a point mutation changes a single nucleotide in the 3' untranslated region (3'-UTR) of a gene this would: change the sequence of the protein produced from the mRNA. decrease protein levels because mRNAs would be degraded. have no effect on translation.
have no effect on translation.
The paper proposes a cure for type 1 diabetes that involves: a combination of careful monitoring of blood sugar, a healthy diet, and daily shots of insulin. implantation of pancreatic β-cells derived from stem cells that have been genetically modified to evade the immune system. transplantation of pancreatic β-cells from a healthy donor coupled with life-long treatment of immunosuppressing drugs.
implantation of pancreatic β-cells derived from stem cells that have been genetically modified to evade the immune system.
Positive and negative transcriptional regulation differ in that: positive regulation requires that a promoter be present; a promoter is not necessary in negative regulation. in positive regulation, the binding of a regulatory protein to the DNA is necessary for transcription to occur; in negative regulation, no such protein is necessary. in positive regulation, the absence of a regulatory protein promotes transcription; in negative regulation, the absence of a regulatory protein promotes transcription. in positive regulation, the binding of a regulatory protein to the DNA is necessary for transcription to occur; in negative regulation, such binding prevents transcription.
in positive regulation, the binding of a regulatory protein to the DNA is necessary for transcription to occur; in negative regulation, such binding prevents transcription.
A mutation in the enhancer for the insulin (INS) gene that increases the affinity of its activator protein binding would: decrease insulin production in pancreatic beta cells and increase insulin production in cells where it is not typically expressed. cause cells that do not usually express insulin to produce the insulin peptide. disrupt insulin signaling because it would change the structure of the insulin peptide. increase the production of insulin, but only in pancreatic beta cells.
increase the production of insulin, but only in pancreatic beta cells.
The lacZ and lacY genes, which produce the enzymes that transport lactose into cells and then breaks it down, are transcribed when: glucose levels are high and lactose levels are low. glucose levels are low, regardless of the level of lactose in the cell. lactose is absent and glucose levels are high. lactose is present, regardless of the level of glucose in the cell. lactose is present and glucose levels are low.
lactose is present and glucose levels are low.
Which condition will result in maximum expression of the lac operon? low glucose and low lactose high glucose and low lactose low glucose and high lactose high glucose and high lactose
low glucose and high lactose
(Multi-select) srRNAs inhibit gene expression by binding: DNA and causing gene degradation. mRNA and triggering RNA degradation. mRNA and altering alternative splicing. mRNA and forming a RISC complex that inhibits translation. DNA enhancers, which block activators from promoting transcription.
mRNA and triggering RNA degradation. mRNA and forming a RISC complex that inhibits translation.
X-inactivation occurs because: proteins produced by the Xist gene bind to just one X chromosome and inhibit gene transcription. noncoding RNAs produced by the Xist gene bind to just one X chromosome and inhibit gene transcription. proteins produced by the Xist gene bind and then degrade one X chromosome. noncoding RNAs produced by the Xist gene bind and then degrade one X chromosome.
noncoding RNAs produced by the Xist gene bind to just one X chromosome and inhibit gene transcription.
A region of prokaryotic DNA consisting of an operator, promoter, and coding sequence for several functionally related genes is called a(n): organized genomic region. operon. closed reading frame. operation. opera.
operon
A mutation that disrupts the repressor binding site in the lac operon would: permit lac operon transcription in the absence of lactose. induce repressor binding to the operator, regardless of lactose levels. inhibit lac operon transcription.
permit lac operon transcription in the absence of lactose.
When a group of functionally related genes located next to one another along the bacterial DNA is transcribed as a single molecule of mRNA, that mRNA is said to be: polymeric. polyproteinacious. polycistronic. polytranslational. polynomial.
polycistronic
The _____ of lactose _____ the binding of the lac repressor protein to the operator and potentially _____ transcription of the structural genes in the operon. absence, increases, increases presence, does not affect, does not affect presence, decreases, increases absence, decreases, increases
presence, decreases, increases
An operon is a: (Hint: The term 'structural gene' means a gene that encodes a protein. It is discussed in the textbook.) region of DNA consisting of the promoter, the operator, and coding sequences for structural proteins. constitutively expressed gene encoding a repressor protein, such as lacI. region of DNA that consists of the promoter and operator sequences, but excludes the structural genes which are regulated by these sequences. region of DNA, found in both prokaryotes and eukaryotes, that controls gene expression. single molecule of RNA encoding more than one protein in prokaryotes.
region of DNA consisting of the promoter, the operator, and coding sequences for structural proteins.
Epigenetic patterns of gene regulation are: random. reversible and responsive to environmental change. permanent never passed from parent to child.
reversible and responsive to environmental change.
MicroRNAs are a subclass of: messenger RNAs. transfer RNAs. ribosomal RNA. splicing RNA. small regulatory RNAs.
small regulatory RNAs.
In prokaryotes: (Select all correct answers.) translation of an mRNA cannot begin until transcription is completed. the primary RNA transcript needs a "cap" at the 5' end for the initiation of translation. the DNA is packaged into nucleoid. the translation of mRNA can begin even before transcription is completed.
the DNA is packaged into nucleoid. the translation of mRNA can begin even before transcription is completed.
Which of the following are constitutively (always) expressed in prokaryotic cells which have the lac operon? the gene for RNA polymerase the gene for the beta-galactosidase enzyme the gene for the lactose transporter the lacI gene, which encodes the repressor protein
the gene for RNA polymerase the lacI gene, which encodes the repressor protein
RNA splicing provides an opportunity for regulating gene expression because: the same introns may be spliced together in different sequences to produce different proteins from the same primary transcript. methylation of spliceosomes controls how rapidly primary transcripts are processed and sent to the cytoplasm. the same exons may be spliced together in different sequences to produce different proteins from the same primary transcript. methylation of the poly(A) tail controls how rapidly the primary transcript can be broken up and spliced back together again.
the same exons may be spliced together in different sequences to produce different proteins from the same primary transcript.
In an operon, different genes have _____ start codon and _____ stop codon. the same; the same their own; the same their own; their own the same; their own
their own; their own
Many genes have multiple enhancer sequences. The multiple enhancer sequences allow multiple: options for RNA editing of the RNA transcript. transcription factors to control gene expression. options for alternative splicing of the RNA transcript. proteins to be made from the same protein-coding gene.
transcription factors to control gene expression.
Enhancer sequences bind: RNA editing complexes. RNA splicing proteins. RNA polymerase. transcription factors.
transcription factors.
