Genetics Unit 2
Arrange the following in the proper order in which they occur during glucocorticoid hormone action. 1. Binding of hormone to receptor 2. Release of HSP90 proteins 3. Entry of hormone into the nucleus Multiple Choice 1, 2, 3 2, 1, 3 2, 3, 1 3, 2, 1
1, 2, 3
Indicate number of Barr bodies with the different karyotypes 1. XY 2. XXX 3. XXXY 4. XXY 5. XXX 6. XX
1. 0 2. 2 3. 2 4. 1 5. 2 6. 1
How many Barr bodies would you expect to find in a cell from a person with the following genotype? 1. XXY 2. XY 3. XX 4. XYY 5. XXX 6. XO (only one X)
1. 1 2. 0 3. 1 4. 0 5. 2 6. 0
You have available a dwarf male mouse with the genotype Igf-2m/Igf-2m and a dwarf female with the genotype Igf-2m/Igf-2. What is the minimum number of generations it would take to produce a normal male? Hint: mice inbreed happily. rev: Multiple Choice 3 1 4 2
2
What is diauxic growth? Explain he roles of CAMP and CAP in this process
C10. Diauxic growth refers to the phenomenon in which a cell first uses up one type of sugar (such as glucose) before it begins to metabolize a second type (such as lactose). This process is governed by gene regulation. When a bacterial cell is exposed to both sugars, the uptake of glucose causes the cAMP levels in the cell to fall. When this occurs, the catabolite activator protein (CAP) is removed from the lac operon so it is not able to be activated by CAP.
What is antisense RNA? Howdoes it affect the translation of a complementary mRNA?
C19. Antisense RNA is RNA that is complementary to a functional RNA such as mRNA. The binding of antisense RNA to mRNA inhibits translation.
Place statements in correct category- Environmental or developmental 1. dan methylation during oogenesis 2. cell type differentiation 3. temperature causes histone modifications 4. diet of royal jelly creates queen bees 5. Xist and Tsix 6. dan covalently modified by toxins
Environmental- diet of royal jelly, temperature causes histone modification, dan covalently modified by toxins Development- dna methylation during oogenesis, Xist and Tsix, cell type differentiation
T or F: An inducer binds to an activator protein and inhibits transcription
False
T or F: An inhibitor regulates an inducible gene.
False
T or F: DNA methylation in eukaryotes, which is associated with transcription inhibition, occurs on A residues at GATC sites.
False
T or F: Expression of how genes results in body segmentation
False
Which of the following were strategies that were used in the ENCODE project? Check All That Apply Identify the DNA sequence of genes Identify the sequence of RNA produced from genes Identify methylation sites Identify transcription factors Identify transcription factor binding sites Identify histones Identify histone modification sites
Identify the DNA sequence of genes Identify transcription factors Identify histones
Variant histones are very prevalent in eukaryotes. The Barr body, the inactive X in eukaryotic females, is associated with which variant histone? Multiple Choice MacroH2A cenH3 H2A.X H2A.Z
MacroH2A
The SOX9 gene appears to play an important role in maleness. Which gene appears to regulate SOX9? Multiple Choice SRY DAX1 DMRT1 Hox genes
SRY
Which of the following is true with regards to enhancer sequences? Multiple Choice They are orientation-dependent. Repressor proteins bind to them. They may be located either upstream or downstream of the promoter. They cannot be downstream of the start of transcription.
They may be located either upstream or downstream of the promoter.
T or F: Parasegments form during gastrulation in Drosophila.
True
Attenuation of the trp operon requires which conditions to be met? Multiple Choice Tryptophan levels must be high, and regions 3 and 4 must pair. Tryptophan levels must be high and regions 2 and 3 must pair. Tryptophan levels must be low and regions 3 and 4 must pair. Tryptophan levels must be low and regions 2 and 3 must pair.
Tryptophan levels must be high, and regions 3 and 4 must pair.
Match the four overlapping phases of animal development with the correct description. 1. Formation of body axes 2. Segmentation of the body 3. Determination of structures within segments 4. Cell differentiation Label 1-4 in order of phase development
formation of body axes- 1 segmentation- 2 determination- 3 differentiation- 4
The order of hox genes on a chromosome is important for the correct expression along the anteroposterior axis of the body. If a mutation occurs that causes one of these genes to be expressed in an area where expression does not normally occur, the outcome is referred to as a Multiple Choice new-function mutation. rearrangement of expression. gain-of-function mutation. loss-of-function mutation.
gain-of-function mutation
When both glucose and lactose are present Multiple Choice cyclic AMP is high so transcription of the lactose operon occurs. the lac repressor binds with the lactose and transcription of the lactose operon occurs. RNA polymerase is able to bind to the operator so transcription of the lactose operon occurs. transcription of the lactose operon is turned off.
transcription of the lactose operon is turned off.
True or false: 1. The LacI gene makes a repressor protein. 2. The structural proteins encoded by the lac operon are involved in lactose synthesis. 3. The CAP protein is an activator that binds to the operator. 4. The product of LacI is an allosteric protein that can undergo a conformational change when allolactose binds to it. 5. CAP binding causes the DNA to bend facilitating RNA polymerase binding
1. true 2. false 3. false 4. true 5. true
T or F: In fruit flies the three germ layers are formed before the celluar blastoderm.
False
T or F: All cells in the body have the same genes, but cells become differentiated due to differences in gene expression.
True
When glucose is present Multiple Choice cyclic AMP is high, the catabolite activator protein (CAP) binds to the activator binding site, and transcription of lactose operon is turned on. cyclic AMP is low, CAP binds to the site activator binding site, and transcription of lactose operon is turned on. cyclic AMP is high, CAP does not bind to the activator binding site, and transcription of lactose operon is turned on. cyclic AMP is low, CAP does not bind to the activator binding site, and transcription of the lactose operon is turned off.
cyclic AMP is low, CAP does not bind to the activator binding site, and transcription of the lactose operon is turned off.
Which of the following proteins does NOT directly interact with TFIID? Multiple Choice Activator protein Co-activator protein Repressor protein Histone deacetylase Mediator RNA polymerase
histone deacetylase
Translation of mRNA transcribed from the trp operon can be regulated by formation of a secondary structure within the mRNA. The mRNA that forms this secondary structure is transcribed from which gene in the trp operon? Multiple Choice trpA trpE trpL operator
trpL
T or F: Lac repressor protein in active in the absence of lactose within a cell.
true
Glucocorticoid hormones activate genes that are involved in which of the following processes? Multiple Choice A.Synthesis of glucose B.Mobilization of fats C.Breakdown of proteins A and B A, B and C
A, B and C
Translational control is usually aimed at preventing the initiation of translation. with regard to cellular efficiency, why do you think this is the case?
C18. It takes a lot of cellular energy to translate mRNA into a protein. A cell wastes less energy if it prevents the initiation of translation rather than stopping the process a later stage, such as elongation or termination.
If a gene is repressible under positive control, what kind of effector molecule and regulatory protein are involved in regulation? Explain how binding of the effector affects the protein
In this case, an inhibitor molecule and an activator protein are involved. The binding of the inhibitor molecule to the activator protein would prevent it from binding to the DNA and thereby inhibit its ability to activate transcription.
Nucleosome-free regions (NFRs) are found in many eukaryotic genes. Select the statement that is not true about NFRs. Multiple Choice They are often found at the beginning and end of a gene. The presence of a NFR is sufficient for gene activation. An NFR is likely required for transcription to occur. The NFR is frequently flanked by variant histones.
The presence of a NFR is sufficient for gene activation.
How many binding sites are there in the lac operon for the lac repressor? Multiple Choice 4 2 1 3
3
A segment of DNA that serves as a boundary between two genes is called a(n) Multiple Choice insulator. NFR. enhancer. silencer.
Insulator
Name the stages of fruit fly development in order Larve Embryo CEllular blastoderm Gastrula Oocyte Syncitial blastoderm
Oocyte Syncytial blastoderm cellular blastoderm gastrula embryo larva
T or F: Polycistronic mRNA is transcribed from the lac operon when lactose is present in the cell
True
The lac repressor binds to what site within the lac operon? Multiple Choice lacZ lacO lacA lacl
lacO
Which of the following is not part of the lac operon? Multiple Choice lacO lacZ lacA lacl lacP
lacl
Choose true or false for the following statements. 1. Steroid hormones are synthesized in the same cells where they function. 2. Estrogen is a gonadocorticoid. 3. Glucocorticoid receptors are membrane bound. 4. Glucocorticoid receptors have a nuclear localization signal that is hidden until a glucocorticoid is bound. 5. Two glucocorticoid receptors function as a homodimer. 6. Glucocorticoid receptors bind to GRE elements which are present on newly synthesized mRNAs.
1. False 2. True 3. False 4. True 5. True 6. False
An operon is repressible. Which combination of small effector molecules and regulatory protein could be involved in turning off transcription?` a. inducer plus repressor b. corepressor plus repressor c. inhibitor plus activator d. inducer plus activator
B and C are correct. In both cases, the presence of the small effector molecule will turn off transcription. In contrast, the presence of an inducer turns on transcription.
What is the correct order of gene expression that results in animal development? A= cell differentiation genes B= maternal-effect genes C= homeotic genes D= segmentation genes Multiple Choice ABCD DCBA BDCA BCAD
BDCA
T or F: In fruit flies, gastrulation occurs before the formation of the celluar blastoderm
False
T or F: Maintenance methylation of DNA is rare and highly regulated.
False
T or F: The first morphogen gradient to provide positional information is established initially in the celluarized embryo.
False
What are the characteristics of Hox genes? Check All That Apply Adjacent groups of Hox genes form Hox complexes. Adjacent groups of Hox genes form Hox complexes In vertebrates, Hox genes play a key role in the anteroposterior axis. In vertebrates, Hox genes play a key role in the anteroposterior axis. Hox genes are present in vertebrates but not in Drosophila. Hox genes are present in vertebrates but not in Drosophila. The coding sequence of Hox genes contains the homeobox. The coding sequence of Hox genes contains the homeobox. Knockout genes have been used to determine the function of Hox genes.
How genes are present in vertebrate but not in drosophila
Which of the following sets of conditions would result in high levels of gene transcription from the lac operon? Multiple Choice Low glucose, high lactose Low glucose, low lactose High glucose, low lactose High glucose, high lactose
Low glucose, high lactose
Which of the following is not a process mediated by histone variants? Multiple Choice Phosphorylation DNA repair Kinetochore binding X chromosome inactivation Telomere maintenance
Phosphorylation
Which of the following are possible if an XY-individual has two copies of DAX? Multiple Choice SOX9 will not be expressed. SRY will be expressed an XY-male will occur. DMRT1 will be expressed.
SOX9 will not be expressed
In the absence of glucose and presence of lactose, allolactose combines with the repressor and allows RNA polymerase to proceed with transcription. Multiple Choice True False
True
T or F: The glucocorticoid receptor is active as a dimer
True
T or F: The presence of small effector molecule may inhibit transcription
True
what is meant by attenuation? is it an example of gene regulation at the level of transcription or translation?
C13. Attenuation means that transcription is ended before it has reached the end of an operon. Because it causes an end to transcription, it is a form of transcriptional regulation even though the translation of the trpL region plays a key role in the attenuation mechanism.
Which of the following is a mechanism to imprint genes? Multiple Choice Methylation of cytosine Methylation of alanine Phosphorylation of adenine Acetylation of cytosine
Methylation of cytosine
Choose true or false for the following statements. 1. Insulators can prevent an enhancer from working on a neighboring gene. 2. Insulators prevent DNA looping. 3. Insulators can prevent chromatin remodeling proteins from working on a DNA region. 4. An insulator is a protein.
1. true 2. false 3. true 4. false
In ChIP-Seq, how does the DNA in the supernatant and the DNA in the pellet differ? Multiple Choice The DNA in the supernatant is associated with histones, while the DNA in the pellet is not bound to histones. The DNA in the supernatant is not bound to histones, while the DNA in the pellet is associated with histones. The DNA in both the supernatant and the pellet are the same, but the DNA in the supernatant is bound to antibody beads. The DNA in both the supernatant and the pellet are the same, but the DNA in the pellet is bound to antibody beads.
The DNA in the supernatant is not bound to histones, while the DNA in the pellet is associated with histones.
The lac repressor Multiple Choice binds to the operator and prevents transcription of the lactose operon. binds to the CAP site and prevents transcription of the lactose operon. binds to the CAP site and facilitates transcription of the lactose operon. binds to the operator and facilitates transcription of the lactose operon.
binds to the operator and prevents transcription of the lactose operon.
Place a single word in each sentence to make it correct The trpR gene encodes a ____________ . The repressor is bound to the operator when tryptophan levels are ____________ . The trp operon is also regulated by ____________ attenuation. The attenuator is similar to rho ____________ termination. The RNA forms stem loops as it is being ____________ . Word Bank: Activator, dependent, high, independent, low, repressor, transcribed, transcription, translation
1. repressor 2. high 3. transcription 4. independent 5. transcribed
Under each of the following sets of conditions, would attenuation occur? a. region 1 is mutant, tryptophan is high, and translation is not occuring b. region 2 is mutant, tryptophan is high, translation is occuring c. region 3 is mutant, high tryptophan, translation is not occuring d. region 4 is mutant, tryptophan is low, translation is not occuring
A. Attenuation will not occur because 2-3 stem-loop will form. B. Attenuation will occur because a 2-3 stem-loop cannot form, so a 3-4 stem-loop will form. C. Attenuation will not occur because a 3-4 stem-loop cannot form. D. Attenuation will not occur because a 3-4 stem-loop cannot form
in the lac operon, how would gene expression be affected of the following segments were missing 1. lac operon promotor b. operator site c. lacA gene
A. No transcription would take place. The lac operon could not be expressed. B. No regulation would take place. The operon would be continuously turned on. C. The rest of the operon would function normally but none of the transacetylase would be made.
What cellular events must occur to establish the body pattern in an animal? Check All That Apply cell division hybrid formation cell migration all cells live cell differentiation apoptosis
All cells live hybrid formation
Would a mutation that inactivated lac repressor and prevented it from binding to the lac operator site result in the constitutive expression of the lac operon under all conditions? Explain. What is the disadvantage to bacterium of having a constitutive lac operon
C12. A mutation that prevented the lac repressor from binding to the operator would make the lac operon constitutive only in the absence of glucose. However, this mutation would not be entirely constitutive because transcription would be inhibited in the presence of glucose. The disadvantage of constitutive expression of the lac operon is that the bacterial cell would waste a lot of energy transcribing the genes and translating the mRNA when lactose was not present.
How would attenuation of trp operon be affected? would the operon be more or less likely to be attenuated? If tRNA synthetase has reduced ability to attach tryptophan to trna
C15. A defective tryptophanyl-tRNA synthetase would make attenuation less likely. This is because the bacterial cell would have a lower amount of charged tRNATrp. Therefore, it would be more likely for the ribosome to stall at the tryptophan codons found within the trpL gene, even if the concentration of tryptophan amino acids in the cell was high. When the ribosome stalls at these tryptophan codons, this prevents attenuation.
Explain difference between cis and trans mutations. Which type can be complemented in a merozygote experiment?
C6. A mutation that has a cis-effect is within a genetic regulatory sequence, such as an operator site, that affects the binding of a genetic regulatory protein. A cis-effect mutation affects only the adjacent genes that the genetic regulatory sequence controls. A mutation having a trans-effect is usually in a gene that encodes a genetic regulatory protein. A trans-effect mutation can be complemented in a merozygote experiment by the introduction of a normal gene that encodes the regulatory protein.
Why is it important to regulate genes? Discuss examples of advantageous bacteria
In bacteria, gene regulation greatly enhances the efficiency of cell growth. It takes a lot of energy to transcribe and translate genes. Therefore, a cell is much more efficient and better at competing in its environment if it expresses a gene only when the gene product is needed. For example, a bacterium will express only the genes that are necessary for lactose metabolism only when the bacterium is exposed to lactose. When the environment is missing lactose, these genes are turned off. Similarly, when tryptophan levels are high within the cytoplasm, the genes that are required for tryptophan biosynthesis are repressed.
How would the interpretation of the Jacob, Monod, and Pardee experimental results change if lacO was mutated instead of lacI? Multiple Choice The lac operon has constitutive expression and O has a trans-effect The lac operon has constitutive expression and O has a cis-effect The lac operon has no expression and O has a cis-effect The lac operon has no expression and O has a trans-effect
The lac operon has constitutive expression and O has a cis-effect
Which of the following would not be considered a reversible posttranslational modification? Multiple Choice phosphorylation proteolytic processing acetylation methylation
proteolytic processing
Place the statements in the correct order Trimethylation of lysine 27 may directly inhibit transcription and recruit PRC1 PRE binding protein binds to PRE and recruits PRC2 to the site Recruitment of pRC1 inhibits transcription through compaction, further modification of histones and interaction with transcription factors PRC2 catalyzes trimethylation
PRE binding protein binds to PRE and recruits PRC2 to the site PRC2 catalyzes trimethylation Trimethylation of lysine 27 may directly inhibit transcription and recruit PRC1 Recruitment of pRC1 inhibits transcription through compaction, further modification of histones and interaction with transcription factors
Choose true or false for the following statements. 1. Insulators can prevent an enhancer from working on a neighboring gene. 2. Insulators prevent DNA looping. 3. Insulators can prevent chromatin remodeling proteins from working on a DNA region. 4. An insulator is a protein.
1. true 2. false 3. true 4. false
Put the terms in one of two categories: Cis or trans epigenetic mechanisms 1. X chromosome activation 2. can be a result of a transcription factor 3. dna methylation 4. cell fusion results in both cell's genes being transcriptionally repressed 5. cell fusion results in no change in transcription of one cell's genes
Cis- dna methylation, X chromosome activation, can be a result of a transcription factor Trans- cell fusion results in no change in transcription of one cell's genes, ell fusion results in both cell's genes being transcriptionally repressed, can be a result of a transcription factor
T or F: Glucocorticoid response elements function as enhancers
true
Do each of the following terms apply to a regulatory protein, segment of dna, or small effector molecule? Repressor Inducer operator site corepressor activator attenuator inhibitor
A. Regulatory protein B. Effector molecule C. DNA segment D. Effector molecule E. Regulatory protein F. DNA segment G. Effector molecule
How can antisense RNA inhibit translation? Multiple Choice An antisense RNA forms a single stranded structure that inhibits translation. An antisense RNA binds to a translation inhibitor protein and prevents translation. An antisense RNA makes a protein that inhibits translation. An antisense RNA binds to a transcript and inhibits translation.
An antisense RNA binds to a transcript and inhibits translation.
If an abnormal repressor protein could still bind allactose but the binding of allaolactose did not alter the conformation of the repressor protein, how would the expression of the lac operon be affected?
C9. It would be impossible to turn the lac operon on even in the presence of lactose because the repressor protein would remain bound to the operator site.
ook at the figure and data to the left. Not all of the operator sites behave the same. Which combination of two operator sites have the lowest amount of repression?
O2 and O3
What would be the consequence if an individual was homozygous for an IRP that could not bind iron but could bind to the IRE? Multiple Choice Unregulated tansferrin receptor levels Increased degradation of ferritin Possible iron toxicity to the cells at levels of iron that would not normally be toxic to a cell There would be no predicted consequence to iron metabolism in the cell
Possible iron toxicity to the cells at levels of iron that would not normally be toxic to a cell
A transcriptional repressor that controls the transcription of gene A is not normally active unless bound by an effector molecule X. In a certain cell, the domain of the repressor that binds X is mutated. With all other factors being the same, what effect do you predict on the transcription of gene A? Multiple Choice The transcription of gene A will not be affected. The effect on the transcription of gene A cannot be predicted. The transcription of gene A will increase. The transcription of gene A will decrease.
The transcription of gene A will increase.
A transcriptional repressor that controls the transcription of gene A is not normally active unless bound by an effector molecule X. In a certain cell, the domain of the repressor that binds to the silencer of gene A is mutated. With all other factors being the same, what effect do you predict on the transcription of gene A? Multiple Choice The transcription of gene A will not be affected. The effect on the transcription of gene A cannot be predicted. The transcription of gene A will increase. The transcription of gene A will decrease.
The transcription of gene A will increase.
What is one technique used by researchers to determine how a mutant allele affects a phenotype? Multiple Choice A knockout gene A homeotic gene A morphogen An ortholog
A knockout gene
If the SRY gene on the male Y-chromosome is damaged or otherwise inhibited so that it is not expressed, which of the following are expected outcomes? Multiple Choice An XY-female will occur Normal male development is expected Abnormal phenotypic male development will occur
An XY-female will occur
The inheritance of traits is sometimes the direct result of specific alleles being present or absent, but it can also be due to the ability of an allele to be ____________ . The definition of epigenetics is the study of mechanisms of heritable traits that ____________ the result of changes in DNA sequence. In ____________ inheritance the transmission of the trait may be based not on the allele but on which parent the allele comes from. The modifications made to DNA in epigenetics results in changes in ____________ association with the DNA. In epigenetics, change can be due to ____________ of DNA Word bank: Mendelian, acetylation, are, protein, dominant, epigenetic, expressed, methylation, are not, recessive
1. expressed 2. are not 3. epigenetic 4. protein 5. methylation
A ____________ is a molecule that promotes developmental changes over time. The final identity of a body region is under the control of a ____________ . A gap gene is also called a ____________ . A ____________ is expressed after fertilization. An ____________ is an example of a homologous gene found in different species. Word bank- Ortholog, homeotic gene, knockout gene, zygotic gene, morphogen, segmentation gene, maternal effect gene
1. morphogen 2. hometic gene 3. segmentation gene 4. zygotic gene 5. ortholog
The Igf-2 locus encodes a growth hormone called insulin-like growth factor 2. Igf-2 is an imprinted gene. The copy of the gene inherited from the father is active and the copy inherited from the mother is silenced. Igf-2 is the wild type allele. There is also a recessive allele Igf-2- The expression of the Igf-2- allele results in dwarf offspring. Two crosses are listed below. Match the cross with the expected phenotype of the offspring. 1. An Igf-2- Igf-2- female crossed with an Igf-2 Igf-2 male 2. An Igf-2 Igf-2 female crossed with an Igf-2- Igf-2- male
1. normal offspring 2. dwarf offspring
Glucocorticoids are ________ hormones secreted by ________ glands. Multiple Choice peptide ; endocrine peptide ; exocrine steroid ; endocrine steroid ; exocrine
steroid ; endocrine
The body size of a mouse can be controlled by the expression of the Igf-2 gene which can be regulated by imprinting. A dwarf female mouse is heterozygous for the lgf-2 gene (lgf-2/lgf-2-). You can conclude that Multiple Choice the lgf-2- allele came from the father. the lgf-2- allele came from the mother. the father was dwarf. the lgf-2 allele came from the father.
the lgf-2- allele came from the father.
Place a single word in each sentence to make it correct. One form of gene expression control found frequently in prokaryotes involves a ____________ , which occurs when an RNA can exist in two different secondary conformations. One conformation of the RNA requires a small molecule binding which stabilizes the ____________ structure. In Bacilus subtilis, a riboswitch controls the ____________ of the thi operon involved in thiamin pyrophosphate synthesis. Riboswitches can regulate transcription, ____________ , and RNA stability. Bacteria use riboswitches extensively; about ____________ of bacterial genes are regulated this way. Word Bank: 10%, 4%, primary, protein, riboswitch, secondary, transcription, translation
1. riboswitch 2. secondary 3. transcription 4. translation 5. 4%
The difference between constitutive gene and regulated gene?
A constitutive gene is unregulated, which means that its expression level is relatively constant. In contrast, the expression of a regulated gene varies under different conditions. In bacteria, the regulation of genes often occurs at the level of transcription by combinations of regulatory proteins and small effector molecules. In addition, gene expression can be regulated at the level of translation or the function of a protein can be regulated after translation is completed.
What is enzyme adaption? How does it occur?
C7. The term enzyme adaptation means that a particular enzyme is made only when a cell is exposed to the substrate for that enzyme. It occurs because the gene that encodes the enzyme that is involved in the metabolism of the substrate is expressed only when the cells have been exposed to the substrate.
The cAMP-CAP binding site is between operators O1 and O3. When cAMP-CAP is bound it facilitates binding of the repressor. Under what conditions would this occur? Multiple Choice High glucose, high lactose Low glucose, high lactose Low glucose, low lactose
Low glucose, low lactose
Mutations may have an effect on the expression of lac operon and the trp operon. Would the following mutations have a cis or trans effect on the expression of the protein-encoding genes in the operon? A. mutation in the operator site that prevents lac repressor from binding to it B. mutation in the lacI gene that prevents lac repressors from binding to DNA c. mutation in the trpL gene that prevents attenuation
A. Cis-effect. It would affect only the genes that are in the adjacent operon. B. Trans-effect. This is a mutation that affects a protein that can move throughout the cell. C. Cis-effect. It would affect only the genes that are in the adjacent operon.
The active Igf-2 allele is inherited from the ____________ Methylation of the sites around the Igf2 locus ____________ binding of the CTC binding factors Binding of the CTCF proteins results in the chromosome ____________ The ____________ may also be methylated Imprinting at the Igf-2 locus may be initiated by methylation at a region between the H19 and Igf2 locus known as the ____________ Methylation in the sperm occurs by a ____________ methylase Word bank: H19 locus, de novo, DMR, enhancer, enhances, female, forming a loop, ICR, maintenance, male, remaining straight, suppresses
1. male 2. suppresses 3. forming a loop 4. DMR 5. ICR 6. de novo
Would you expect attenuation to occur if tryptophan levels were high and mutations changed the attenuator sequence from UUUUUUUU to UGGUUGUC. explain why or why not
C16. The addition of Gs and C into the U-rich sequence would prevent attenuation. The U-rich sequence promotes the dissociation of the mRNA from the DNA, when the terminator stem-loop forms. This causes RNA polymerase to dissociate from the DNA and thereby causes transcriptional termination. The UGGUUGUC sequence would probably not dissociate because of the Gs and C. Remember that GC base pairs have three hydrogen bonds and are more stable than AU base pairs, which have only two hydrogen bonds.
Why might all histone variants not be expressed by all cells? Multiple Choice Because not all cell types have the DNA for all histone variants Because some histones are not needed in certain cell types Because some histones are not able to bind to DNA Because some histones have no known function
Because some histones are not needed in certain cell types
The lac repressor is inactivated by binding to which of the following? Multiple Choice lactose betagalactosidase transcription factors glucose allolactose
allolactose
Each statement describes a type of gene regulation. Determine if it describes regulation at the transcription, translation or post-translation level. 1. Genetic regulatory proteins bind to the DNA. 2. A transcription terminator forms in the RNA. 3. Repressor proteins bind to an mRNA and prevent ribosome binding. 4. Riboswitches produce an RNA conformation that prevents ribosome binding. 5. Antisense RNA binds to the mRNA. 6. The product of a metabolic pathway inhibits the first enzyme in a pathway. 7. A protein is covalently modified.
1. transcription 2. transcription 3. translation 4. translation 5. translation 6. post translation 7. post translation
Using three examples, describe how allosteric sites are important in the function of genetic regulatory proteins
1. lac operon: The binding of allolactose causes a conformational change in the repressor protein and removes it from the operator site. 2. lac operon: The binding of cAMP to CAP causes a conformational change that allows it to bind to the promoter region. 3. trp operon: The binding of tryptophan to trp repressor causes it to bind to the operator site and inhibits transcription.
How are actions of lac repressor and trp repressor similar and how are they different with regard to their binding to operator sites, their effects on transcription and the influences of small effector molecules?
The two proteins are similar in that both bind to a segment of DNA and repress transcription. They are different in three ways: (1) They recognize different effector molecules (i.e., the lac repressor recognizes allolactose, and the trp repressor recognizes tryptophan. (2) Allolactose causes the lac repressor to release from the operator, while tryptophan causes the trp repressor to bind to its operator. (3) The sequences of the operator sites that these two proteins recognize are different from each other. Otherwise, the lac repressor could bind to the trp operator, and the trp repressor could bind to the lac operator.
When both glucose and lactose are absent, transcription of the lac operon occurs. Multiple Choice True False
False
True or False: 1. coat color in mice is only controlled by methylation of a promoter 2. coat color in mice can be correlated with the amount of methylation of a transposable element 3. coat color in mice is controlled only by dietary factors 4. exposure of pregnant female mice to a specific diet will result in all progeny being psuedoagouti phenotype 5. methylation of a TE promoter may influence coat color 6. If transposable element is not upstream from the agouti allele there should be no influence of diet on coat color
True- methylation of a TE promoter may influence coat color, coat color in mice can be correlated with the amount of methylation of a transposable element, If transposable element is not upstream from the agouti allele there should be no influence of diet on coat color False- coat color in mice is controlled only by dietary factors, coat color in mice is only controlled by methylation of a promoter, exposure of pregnant female mice to a specific diet will result in all progeny being
In Drosophila melanogaster, fruM expression in males affects what tissue? Multiple Choice the nervous system germline cells somatic cells the endocrine system
the nervous system
Two phenotypically normal mice produce a single F1 male progeny that is also phenotypically normal. This F1 male is mated with an lgf-2/lgf-2 female and ½ of the progeny are dwarf. Where did the lgf-2- allele in the F2 progeny originate? Multiple Choice The phenotypically normal F1 generation female The parental generation female that had to have been heterozygous (lgf-2/lgf-2-) The parental generation male The lgf-2- could have come from either the male or female in the parental generation
The parental generation female that had to have been heterozygous (lgf-2/lgf-2-)
The selection of which chromosome is inactivated is a ____________ process. The inactive X chromosome in a human female somatic cell is called a ____________ . Although the Tsix transcript is produced by both X chromosomes the Xist transcript is only produced from the ____________ chromosome. The symmetry break that occurs is due to localization of ____________ to one X chromosome. Presence of the xist transcript on the Xi chromosome results in the recruitment of ____________ . At least some genes are silenced on inactive X chromosomes by ____________ . Word bank- Barr body, CTCFs, H2B, euchromatin, active, demethylation, inactive, macroH2A, methylation, pluriptency factors, random, selected
1. random 2. barr body 3. inactive 4. CTCFs 5. macroH2A 6. methylationThe selection of which chromosome is inactivated is a ____________ process. The inactive X chromosome in a human female somatic cell is called a ____________ . Although the Tsix transcript is produced by both X chromosomes the Xist transcript is only produced from the ____________ chromosome. The symmetry break that occurs is due to localization of ____________ to one X chromosome. Presence of the xist transcript on the Xi chromosome results in the recruitment of ____________ . At least some genes are silenced on inactive X chromosomes by ____________
