Genetics Exam 3

(Hwangbo Q) An XX Drosophila fertilized egg is a homozygous mutant for the gene sex-lethal (sxl). What effect do you predict this will have on phenotype? a) It will cause development as a male. b) It will cause development as a female. c) It will be intersex d) It will have no effect on this fly, but will on male offspring. E) It will have no effect on this fly, but will on female offspring

A

(Hwangbo Question) If a promoter region is mutated in such a way that it can no longer be methylated, what would the most likely effect be? a) The gene linked to that promoter would be over expressed. b) The gene linked to that promoter would not undergo replication. c) The gene linked to the promoter would be under expressed. d) The gene linked to the promoter would be expressed at regular levels. The gene linked to the promoter would still be expressed, but the protein should contain different amino acids

A

(Student Q) CRP binds near the lac promoter when ___: A. cAMP is high B. cAMP in low C. cAMP isn't present D. cAMP is mutated

A

(Recitation Q) Which of the following are some examples of each of cis regulatory elements? You can pick one or more A. Silencer B. Enhancer C. Repressor D. deactivator

A and B.

(Recitation Q) What are the two types of gene regulation control systems? *Choose two* A. Inducible B. Enhancer C. Repressible D. Silencing

A and C

(Recitation Q) What are the differences between cis and trans regulatory elements? *Choose two.* A. Cis regulatory elements are built into the DNA and can either be down stream or upstream B. Cis regulatory elements are added on, but only upstream from the site. C. Trans regulatory elements are added on, influenced by outside elements. D. Trans regulatory elements are built in and can either be down stream or upstream.

A and C.

(Hwangbo Q) Attenuation uses _____ to control ____ a) Translation, transcription b) Transcription, translation c) Translation, elongation d) Elongation, Translation

A.

(Hwangbo Question) Usually, bacteria only make tryptophan when tryptophan is absent or available in low concentration. However, a particular bacterial mutation makes tryptophan all the time whether or not tryptophan is present. What could explain this phenotype? a) the terminator hairpin is unable to form b) the antiterminator hairpin is unable to form c) trpE is mutated d) trpD is mutated trpA is mutated

A.

(Student Q) Under catabolite repression, when is the lac operon expressed at its highest levels? A. When lactose is available and glucose is low B. When lactose is unavailable and glucose is high C. When lactose is unavailable and glucose is low D. When lactose is available and glucose is high

A. ex) (Lecture 15, Slide 17)

(Hwangbo Sample Q) 1. For a(n) ___ operon, transcription normally does NOT take place, and it is kept off by a(n) ___. a) inducible; activator b) inducible; repressor c) repressible; activator d) repressible; repressor inducible; inducer

B Ex) Recitation Confirmed

(student Q) The trp operon is an example of which of the following? A. Genetic attenuation B. repressible operon C. Premature termination D. Trp codon

B. Ex) The trp operon is a repressible system. The primary difference between repressible and inducible systems is the result that occurs when the effector molecule binds to the repressor.

(Hwangbo Q) 1. When tryptophan is ( _______) , charged tRNA's are (_____ ) made, and ribosomes (_________ ) . a. high ; easily ; die off b. low ; not easily ; are stalled c. low ; easily ; keep moving forward d. high ; not easily ; are stalled

B. Ex) You can't charge tRNAs with Tryptophan you don't have.

(Hwangbo Q) 1. In a eukaryote, what is the best way to compare the number of genes in a genome to the number of proteins that the genome can produce and why? a) The number of proteins is equivalent to the number of genes due to alternative splicing. b) The number of proteins is usually fewer than the number of genes due to alternate splicing. c) The number of proteins is usually greater than the number of genes due to alternate splicing. d) The number of proteins is usually fewer than the number of genes due to histone modification. e) The number of proteins is usually greater than the number of genes due to histone modification.

C

(Student Q) Which of the following is responsible for rRNA cleavage during pre-rRNA processing? A. U1 B. U2 C. U3 D. U4 E. U5 F. U6

C

(Recitation Q) Which of the following are some examples of each of trans regulatory elements? You can pick one or more. A. Silencer B. Enhancer C. Repressor D. deactivator

C and D.

(Hwangbo Q) Even though both lens cells and liver cells have numerous transcription factors that are present in both cells, the lens cell makes the crystallin protein (not albumin), whereas the liver cell makes albumin (not crystallin). Which of the following explains this cell specificity? a) At fertilization, specific cells are destined for certain functions. b) The activators needed for expression of the crystallin gene are present in all cells. c) Different specific transcription factors made in each cell determine which genes are expressed. The promoters are different for the different genes

C.

(Hwangbo Q) If a particular operon encodes enzymes for making an essential amino acid and is regulated like the trp operon, then a) the amino acid inactivates the repressor. b) the repressor is active in the absence of the amino acid. c) the amino acid acts as a corepressor. d) the amino acid turns on transcription of the operon. e) the amino acid acts as an attenuator

C.

(Hwangbo Question) When referring to attenuation in regulation of the trp operon, it would be safe to say that when there are high levels of tryptophan available to the organism, ________. a) the trp operon is being transcribed at relatively high levels b) translational termination is likely c) transcriptional termination is likely d) tryptophan is inactivating the repressor protein e) ribosomes are stalling during translation of the attenuator region

C.

(Hwangbo Sample Q) Altering patterns of gene expression in prokaryotes would most likely serve an organism's survival by ________. a) organizing gene expression, so that genes are expressed in a given order b) allowing each gene to be expressed an equal number of times c) allowing an organism to adjust to changes in environmental conditions d) allowing environmental changes to alter a prokaryote's genome fighting DSHB

C. Ex) Recitation Confirmed

(Student Q) Which one of the following is incorrect/false about miRNA? A) origin is RNA transcribed from distinct gene B) 21-25 nucleotides C) degradation of mRNA and inhibition of translation D) target genes from which they were transcribed

D

(student Q) An insulator is __ a) Between a promoter and silencer on a target gene b) Between a promoter and enhancer on a target gene c) Between a promoter and silencer on a nontarget gene d) Between a promoter and enhancer on a nontarget gene

D

(student Q) Scientist discover a new operon in eukaryotes. Upon further investigation they find a GC and CAAT sequence upstream of the TATA box and BRE motifs. When this sequence is removed the mutant shows decreased levels of basal transcription. What sort of sequences are these? A. Structural genes B. Insulators C. Core Promoters D. Proximal-Promoter Elements

D

(Hwangbo Q) Which of the following lac genotypes would allow for beta galactosidase to be expressed constitutively even in the absence of lactose?(CHOOSE TWO) + : wild type c or a - : means mutation a) I+ P+ O+ Z+ Y+ A+ b) I+ P- O+ Z+ Y+ A+ c) I+ P+ O+ Z- Y+ A+ d) I+ P+ Oc Z+ Y+ A+ e) P+ O+ Z+ Y+ A+

D AND E. ex) D has a mutated O so it doesn't matter that the repressor gene (I+)functions. E has *no* repressor gene (I+), so it doesn't matter that O isn't mutated.

(Hwangbo Q) When both lactose and glucose are available to E. coli, which part of the lac operon regulation assures that glucose will be metabolized first? a) The repressor binds to the operator in the absence of lactose. b) The repressor cannot bind to the operator in the presence of lactose. c) Permease allows lactose to enter the cell when lactose enters the cell. d) CAP binds to cAMP and then to the promoter only in the presence of low glucose. e)RNA polymerase transcribes the lac operon to make a single RNA molecule.

D.

Student Q) What is the name of Hwangbo's friend's dog and what is it dying of? A. Rusty, heart disease B. Holly, diabetes C. Barry, rabies D. Dusty, cancer

D. :(

(Hwangbo Q) 1. UASs (upstream activating sequences) are DNase hypersensitive. This means that ________. a) more than one strand of DNA exists in each UAS b) each UAS is likely to be single stranded c) each UAS has more histone-binding sites than non-UAS sites d) a UAS is constitutively open e) any given UAS is composed of a double-stranded site with a bound repressor

D. always prone to gene regulation

(Hwangbo Q) 1. The discovery of RNA interference (RNAi) led to its use in biotechnology and medicine. All of the following are examples of how RNAi could be used in biotechnology or medicine, EXCEPT ________. a) to treat a disease characterized by the buildup of a specific protein b) to treat a disease characterized by the normal expression of a mutated gene c) to treat a disease characterized by the overexpression of a nonmutated gene d) to treat a disease characterized by a gene that is not expressed e) to study loss-of-function phenotypes of specific genes in a model research organism

D. ex) A lot of treatments for genetic diseases are to block out the mutation with some sort of inhibitor. There is not much that can be done to make a gene express that isn't doing so or is totally absent.

(Hwangbo Q) If Mia moves the operator to the far end of the operon, past the transacetylase (lacA) gene, which of the following processes would likely occur when the cell is exposed to lactose? a) The inducer will no longer bind to the repressor. b) The repressor will no longer bind to the operator. c) The operon will never be transcribed. d) The genes of the lac operon will be transcribed continuously. e)The operon will be permanently repressed

D. ex) An operator sequence located at the 5′ end serves as a binding site for a repressor protein that blocks RNA polymerase. If the operator sequence is at the *end of the operon*, repressed or not, all enzymes will be transcribed.

(Hwangbo Question) Within a cell, the amount of protein made using a given mRNA molecule depends partly on a) the degree of DNA methylation. b) the number of introns present in the mRNA. c) the types of ribosomes present in the cytoplasm. d) the rate at which the tRNA is degraded. the rate at which the mRNA is degraded

E

(Student Q) You are working with a Lac operon and you decide to let it go through transcription but there is nothing expressed the next day. What could have caused this to occur? A. Mutation at regulatory region B. Mutation at the genes C. Mutation of the repressor to keep it binded to the sequence D. There was too much glucose in the system E. All the above

E

(Student Q) Is the following statement True or False? "The concentration of cAMP is inversely proportional to the level of available glucose" False True

True

(Recitation Q) All cells have the same kind of DNA within an organism . True False

True.

(Student Q) What regions of mRNA transcribed by the Trp operon for the attenuation hairpin? A. Regions 3 and 4 B. Regions 2 and 3 C. Regions 1 and 2 D. Regions 1 and 4 E. The attenuation hairpin structure does not form on specific regions

A

(Student Q) The relationship between glucose and cAMP is an example of what type of regulation? a. Positive Control b. Negative Control c. Protein synthesis d. Catabolite inducer

A. ex) "The positive control of gene expression refers to the case when a gene is expressed in presence of an activator or inducer." Glucose inhibits the cap-cAMP complex that helps RNA poly translate. That complex is an activator. *transcriptional activator is a protein that increases transcription of a gene or set of genes. * an inducer is a molecule that regulates gene expression

(Hwangbo Q) To activate the transcription of permease (and the whole lac operon), lactose needs to be present in the cell. How can lactose get in the cell when the permease gene is not activated? a) The repressed lac operon is never completely repressed. b) There is a second permease in the genome that initially transports lactose. c) Lactose freely moves across the plasma membrane. d) Though the lac operon has been studied for many years, this mystery is unsolved. e) None of the above.

A. ex) It's always on at basal levels.

(Student Q) If ATP levels are low, what possible molecule is harder to create? a. cAMP b. CAP c. Allolactose d. Silencer Proteins

A. ex) cAMP is cyclic adenosine monophosphate and is synthesized from ATP-- Adenosine *tri*phosphate.

(Student Q) In eukaryotic gene regulation, enhancers are ______ than in prokaryotic gene regulation. A. Less commonly found B. More commonly found C. Much smaller D. Much larger

B

(Student Q) What does the lacY structural gene do? A. Encodes B-galactosidase, an enzyme that converts disaccharide lactose to monosaccharides glucose and galactose B. Specifies primary structure of permease, an enzyme that facilitates entry of lactose into bacterial cell C. Encodes enzyme transacetylase, which may be involved in removal of toxic by-products of lactose digestion from the cell D. None of the above E. All of the above

B. ex) (lec 14, slide 20)

(Hwangbo Q) A regulatory sequence of DNA that is 10,000 base pairs away from the gene it regulates is mutated. The result is that the gene being regulated is now expressed at a higher rate compared to when this regulatory sequence was not mutated. What would this sequence of DNA best be called? a) Insulator b) activator protein c) enhancer d) silencer e) zinc finger motif

D

(Hwangbo Question) Genetic regulation in bacteria can involve alterations in RNA secondary structure. What phenomenon occurs in the trp operon that involves such alterations? a) transcription b) capping c) polyadenylation of the 3′ end of the mRNAs d) intron processing e) attenuation

E

(Student Q) Which describes the summary of the operon model? A. Invokes series of molecular interactions between proteins, inducers, and DNA B. No lactose present: enzymes are not needed and expression of genes encoding enzymes is repressed C. Lactose present: indirectly induces activation of genes by binding depressor D. All lactose metabolized: none is available to bind to repressor and transcription is repressed E. All of the above

E. ex) (lec 14, Slide 29)

(HwangboSampleQ) Where does posttranscriptional regulation take place in eukaryotic cells? a) Nucleus b) Nucleolus c) Cytosol d) Endoplasmic reticulum e) Both nucleus and cytosol

E. ex) Recitation Confirmed.

(Student Q) Which of the following is/are NOT a level of gene expression regulation? Transcriptional control Protein activity control mRNA degradation control Cis-acting sequence control a. i only b. ii only c. iii only d. iv only e. i and iii only f. i , ii, and iii only g. All of the above

F

(Student Q) When levels of tryptophan are high, the trp operon is ______. A. Expressed B. Repressed C. Turned "on" D. Turned "off" E. Both a and c F. Both b and d

F Ex) This question is flagged and may be removed. The way this originally read was that the trp operon would be both turned on and turned off. I believe this was a typo. I have not fully confirmed the answer I have corrected this to, which is that is it "repressed and turned off."

(Student Q) The ______ strand is what the attenuator loop forms on. This strand will then be released from the ____ due to the weak base pairings of uracil and guanine. A. DNA; mRNA strand B. mRNA; DNA strand C. DNA; ribosome D. mRNA; tRNA

B

(Hwangbo Sample Q) Which of the following processes would result from a mutation that deactivates a regulatory gene of a repressible operon in an E. coli cell? a) continuous transcription of the regulatory gene controlled by that operon b) continuous transcription of the structural gene controlled by that regulator c) complete inhibition of transcription of the structural gene controlled by that regulator d) irreversible binding of the repressor to the operator e) continuous translation of the mRNA because of alteration of its structure

B. Ex) Recitation Confirmed. "In the Operon Model, the regulatory genes are those that code for the production of regulatory proteins. For instance, the regulatory gene in lac operon is the lac I gene that codes for the lac repressor. The repressor protein binds to operator gene, which consequently prevents the production of a specific enzyme."

(Recitation Q) Do glucose and cAMP have a positive or negative correlation to each other and explain what happens. A. Positive. The concentration of cAMP is inversely proportional to the level of available glucose. High Glucose means low cAMP. B. Negative. The concentration of cAMP is directly proportional to the level of available glucose. Low Glucose means low cAMP. C. Positive. The concentration of cAMP is directly proportional to the level of available glucose. High Glucose means high cAMP. D. Negative. The concentration of cAMP is inversely proportional to the level of available glucose. High Glucose means low cAMP.

D.

(Student Q). In the transcriptional regulation of the GAL gene in the yeast family, which regulatory gene is the repressor, and which complexes with the repressor to open up the activator binding site? A. GAL 4 is the repressor, and GAL 3 will complex with it B. GAL 3 is the repressor, and GAL 4 will complex with it C. GAL 4 is the repressor, and GAL 80 will complex with it D. GAL 80 is the repressor, and GAL 3 will complex with it E. GAL 80 is the repressor, and GAL 4 will complex with it

D.

(Hwangbo Q) 1. A researcher is studying plant development. She isolates a mutant and discovers that the piece of DNA that is mutated does not code for a protein. However, this piece of DNA is complimentary to a gene known to function in early embryonic plant development. The mutant she identified most likely functions as a(n) ________. a) ribosomal RNA (rRNA) b) transfer RNA (tRNA) c) intron d) general transcription factor known to regulate many different genes e) microRNA (miRNA)

E

(Hwangbo Question) Muscle cells differ from nerve cells mainly because they a) contain different genes. b) use different genetic codes. c) have unique ribosomes. d) express same but independent genes express different genes

E

(student Q)Which of the following operons have the attenuation mechanism? A. Threonine B. Histidine C. Leucine D. Phenylalanine E. All of the above

E

(Student Q) Under what conditions is the lac operon transcribed minimally ? a. High Glucose + High Lactose b. Low Glucose +Low lactose c. High Lactose + Low Glucose d. High lactose + No glucose

A. Ex) Specifically, the lac operon is always transcribed. However, if there is High Glucose + any amount of lactose, it will be transcribed at low levels in the background while glucose is prioritized.

(Hwangbo Q) The GAL gene system in yeast is used to metabolize galactose. In the presence of galactose, the GAL genes are expressed; however, in the absence of galactose, the GAL genes are repressed. A yeast mutant is discovered that continuously expresses the GAL genes in the presence or absence of galactose. Which GAL gene is likely mutated? a) GAL4 b) GAL80 c) GAL3 d) GAL1 e) GAL 10

B

(Student Q) Transcription is activated by _____ in response to galactose. A. Gal 7 B. Gal 4 C. Gal 80 D. Gal 2

B

(Student Q) What two processes are coupled with attenuation with the Trp operon? A. Transcription and replication B. Transcription and translation C. Translation and mRNA processing D. Replication and mRNA processing

B

(student Q) A mutant yeast cell is created that prevents binding of GAL 80 to GAL 4. What will happen to the operon? A. It will permanently be turned off B. It will permanently be turned on even when no galactose is present C. Nothing GAL 3 can take GAL 80 place in the operon

B

(Hwangbo Q) As a _________ operon, the trp operon is affected by the presence of tryptophan as: a) Repressible; tryptophan binds to a repressor, inactivating it and allowing RNA polymerase to bind to the operator. b) Repressible; tryptophan acts as a corepressor, allowing the repressor bind the operator effectively blocking RNA polymerase from binding. c) Inducible; tryptophan binds to a repressor, inactivating it and allowing RNA polymerase to bind to the operator. Inducible; tryptophan acts as a corepressor, allowing the repressor bind the operator effectively blocking RNA polymerase from binding

B.

(Student Q) What happens if there is a mutation on the GAL 4 gene? A. The GAL 80 would not bind to UAS B. The transcription would not be activated C. The transcription would be activated

B.

(Hwangbo Question) Zack isolated a yeast mutant that contains histones resistant to acetylation. What phenotype would you predict for this mutant? a) The mutant will grow rapidly. b) The mutant will require galactose for growth. c) The mutant will show decreased levels of gene expression. d) The mutant will show increased levels of gene expression. e) The mutant will switch sex

C

(Recitation Q) How much lac mRNA would be transcribed if both lactose and glucose were present? A. None, because the cell prefers glucose. B. Both lac and glucose operons will be simultaneously expressed in equal amounts to take advantage of both food sources. C. If both are present, glucose operons will be prioritized but some lac mRNA would still be made.

C. Ex) The repressed lac operon is never completely repressed and always on even at basal levels. Bonus: Basal is defined at a minimal level that is necessary for health or life, indicating a standard low level of activity of an organism, as during total rest

(Student Q) Which of the following is true about the enzyme histone acetyltransferase (HAT)? a) Adds an acetyl group on the side chain arginine b) Makes genes unavailable for transcription c) Increases affinity of a histone to DNA d)Neutralizes the net charge of protein

D

(Recitation Q) What are the main enzymes of the lac operon? A. Amylase, permease, β-galactosidase, B. Lipase, β-galactosidase, transacetylase C. β-galactosidase, Amylase, Lipase D. Permease, β-galactosidase, transacetylase

D. Ex) Amylase and Lipase are enzymes produced by the salivary glands and the pancreas of complex eukaryotes. Not the enzymes produced by the operons of a bacteria.

(Hwangbo Sample Q) What would occur if the repressor of an inducible operon were mutated so it could not bind the operator? a) irreversible binding of the repressor to the promoter b) reduced transcription of the operon's genes c) buildup of a substrate for the pathway controlled by the operon d) continuous transcription of the operon's genes e) continuous translation of the repressor gene

D. Ex) Recitation Confirmed

(Hwangbo Q) DNA-binding proteins such as transcription factors, activator, and repressors interact _____with DNA, usually via _____ bonds. a) dynamically; hydrogen b) dynamically; covalent c) permanently; hydrogen d) permanently; phosphodiester e) permanently; ionic

A. ex) Most things in the human body aren't and shouldn't be permanent. Covalent bonds take a lot of energy to break, so you wouldn't want them in a situation where things are zipping along very quickly.

(Student Q) Which promoter structure is not involved in DNA sequencing elements? A. TATA box B. TFIIB recognition element C. RNA Polymerase D. Downstream promoter element

C

(Hwangbo Sample Q) There is a mutation that is found in E. coli in the repressor that results in a molecule known as a super-repressor because it represses the lac operon permanently. Which of the following characteristics would you expect to observe in such a mutant? a) It cannot bind to the operator. b) It cannot make a functional repressor. c) It cannot bind to the inducer. d) It makes a repressor that binds CAP. e) It can always bind to the operator

C. Ex) Recitation Confirmed. The inducer is lactose and it can't bind to the repressor, so the repressor doesn't release from the operator.

(Hwangbo Q) If Lucas moves the repressor gene (lacI) to a position at some several thousand base pairs away from its normal position, which of the following results would be expected? a) The repressor will no longer bind to the operator. b) The repressor will no longer bind to the inducer. c) The lac operon will be expressed continuously. d) The lac operon will function normally. e) The lac operon will not be able to sense the concentration of glucose.

D. Ex) The repressor gene makes repressors all the time. These repressors go and float around in the cytosol in total chaos. Distance doesn't matter in this case, because any one of them can float along and do the job.

(Student Q) Which of the following is true concerning attenuation? A. Attenuation is a process found within the leader region of the Trp operon B. Attenuation acts as a fine-tuning layer of regulation in order to save energy in some prokaryotic cells C. Attenuation causes a specific hairpin sequence which forces RNA polymerase to disassociate, repressing the Trp operon to a greater extent D. The mRNA strand transcribed before attenuation stopped it short will not contain structural genes and is degraded easily E. All of the above

E.

(Hwangbo Question) Under what conditions does the trp repressor block transcription of the trp operon? a) when the repressor binds to the inducer b) when the repressor binds to tryptophan c) when the repressor is not bound to tryptophan d) when the repressor is not bound to the operator when the operator binds to tryptophan

B.

(Student Q) Which type of bond do transcription factors not form when they interact with bases? a. van der waals b. Covalent c. Hydrogen d. Hydrophobic

B. Ex) "Transcription factors interact with their binding sites using a combination of electrostatic (of which hydrogen bonds are a special case) and Van der Waals forces." Covalent bonds require too much energy to break to be conducive to the transcription process.

(Hwangbo Q) In positive control of several sugar metabolism-related operons, the cAMP receptor protein (CRP) binds to DNA to stimulate transcription. Which of the following environmental conditions causes an *increase* in CRP activity in stimulating transcription? a) an increase in glucose and an increase in cAMP b) a decrease in glucose and an increase in cAMP c) an increase in glucose and a decrease in cAMP d) a decrease in glucose and a decrease in the repressor e) a decrease in glucose and a decrease in CRP

B. ex) Short version: cAMP and Glucose have an inverse relationship. Glucose inhibits the cap-cAMP complex. RNA poly needs the complex to bind to the promoter region to keep it steady, or it will fall right off as soon as it starts. (cap-cAMP complex is RNA poly training wheels) Long Version: Sometimes the bacteria exists in a space where both lactose and glucose are in good supply. In this case, since it favors glucose, it will prioritize the glucose uptake. First, cAMP (cyclic adenosine monophosphate) must bind to Catabolite-activating protein (CAP) to create a CAP-cAMP complex. Glucose inhibits adenyl cyclase causing a decline in the level of cAMP in the cell. If there isn't enough cAMP to bind to CAP, the complex will not be made.The lack of this complex reduces the expression of the lac operon when glucose is present- by NOT binding to the promoter region. This is because RNA polymerase does not bind very efficiently unless CAP-cAMP complex is also bound to facilitate the process.

(student Q) The lac y gene is considered which of the following? A) structural gene in the trp gene B) structural component of the lac promoter region C) structural component of the lac operon. D) negative regulator of gene transcription

C

(Student Q) The lacZ gene encodes for β-galactosidase, used to cleave the disaccharide lactose. What two monosaccharides make up lactose? a. Two glucose monosaccharides b. Two allolactose monosaccharides c. Two galactose monosaccharides d. One glucose monosaccharide and one galactose monosaccharide e. One galactose monosaccharide and one allolactose monosaccharide

D. ex) When lactose is cleaved, it doesn't perfectly make two glucose molecules- it results in one glucose and one galactose monosaccharide. It seems Galactose then receives some modifications from other enzymes to eventually enter the glycolysis cycle itself.

(Student Q) Which protein modification method is most closely linked to protein degradation? A. Ubiquitination B. Methylation C. Chromatin modification D. RNA interference E. Histone modification

A.

(Recitation Q) What is the main difference between positive and negative control in relation to gene regulation? *Choose Two* A. A positive inducer has to bind to increase the speed of gene expression. B. Positive (Inducer) is always on and has to be turned off. C. Genes are always expressed unless a negative (repressor) is present D. Genes are always expressed unless a negative (repressor) is present and acts as the 'off switch' by being activated.

B and C. Ex) B: If Inducer is not turned off, it acts like nitrous fuel to speed up the process. C: Unless there is something to prevent expression, such as a repressor, most genes are always expressed. A Repressor acts as the 'off switch'. A is wrong because inducers are always on, so binding is not in the situation. D is wrong because repressors don't have to be activated to repress. Still don't love the wording of the question answers but I think it's correct.

(Hwangbo Sample Q) To translate the three enzymes of the lac operon, _____ mRNA molecule(s) is/are transcribed. a) 0 b) 1 c) 2 d) 3 e) 4

B. Ex) Recitation Confirmed

(Student Q) Maskin is involved in the regulation of the poly-A tail. A _____ regulatory element sequence on the mRNA is recognized and bound by a special RNA-binding protein. This binding _______ the poly-A tail. The outcome is that the poly-A tails are bound by _____ molecules of Poly-A Binding proteins. This ______ the mechanism for translation initiation. Maskin then comes along to bind to the cap binding protein, elF4e, blocking eLF4G. This causes the mRNAs to be _________. A. Trans, lengthens, denser, stabilizes, transcriptionally repressed. B. Cis, shortens, fewer, destabilizes, translationally repressed. C. Trans, lengthens, more, destabilizes, translationally repressed. D. Cis, lengthens, fewer, destabilizes, transcriptionally repressed.

B. ex) (Klug, p 426)

(Hwangbo Question) Which of the following mechanisms is used to coordinate the expression of multiple, related genes in eukaryotic cells? A) Environmental signals enter the cell and bind directly to promoters. B) A given gene may have multiple enhancers, but each enhancer is generally associated with only that gene and no other. C) The genes are organized into a large operon, allowing them to be coordinately controlled as a single unit. D) A single repressor is able to turn off several related genes

B. ex) Genes often have multiple enhancers, and each enhancer can provide diverse transcriptional regulatory instructions to modulate the levels of gene expression depending on differing biological conditions

(Student Q) A mutation in the repressor would cause the reporter gene to measure ______ mRNA levels. A. Lower B. Higher C. The same D. Become unable to measure the mRNA levels at all.

B. ex) Reporter genes are genes whose products can be readily assayed subsequent to transfection, and can be used as markers for screening successfully transfected cells, for studying regulation of gene expression". Imagine the green dye. If a gene for green color was not repressed, shown by there being a lot of green color present, that means none of the mRNA got repressed either.

(Student Q.) The nucleus has mutated to have fewer nuclear pores. Which of the methods of gene regulation would have less opportunity to occur at normal rates? 1) addition of a 5′ cap 2) the removal of non coding introns aka RNA Splicing 3) synthesis of a 3′ poly-A tail. 4) alternative splicing to generate spliceoforms 5)ARE (adenosine-uridine rich element) binding by the stabilizing RBP, HuR 6) deadenylation-dependent and independent decay A. 1-4 B. 4-6 C. All of them will be reduced, a cell having fewer nuclear pores affects everything. D. None of them will be reduced because nuclear pores will not have any effect on gene regulation

B. ex) The answer depends on two things. That you know that mRNA travels through the nuclear pore after a handful of translation regulation methods. And which one of those are before exiting the nucleus and after leaving the nucleus.

(student Q) miRNA binds to the RISC (RNA-induced silencing complex) and does what? A. Amplifies the transcribed mRNA B. Assists in transport of mRNA to ribosomal complex C. Silences specific genes by blocking translation or signaling for its degradation D. Silences genes by degrading pre-mRNA

C

(student Q)What is the function of transacetylase in relation to the lac operon mechanism?A. Facilitates entry of lactose into the bacterial cell B. Converts disaccharide lactose to monosaccharide glucose and galactose C. Removes toxic by-products of lactose digestion D. Ask DS for the answer because I am not sure

C

(Student Q) You are working with the lac operon and notice that there is a mutation that causes acetyl cyclase to not work properly. What would happen to the gene expression of this lac operon with high lactose levels and low glucose levels? A. The lac operon would be transcribed more efficiently because acetyl cyclase acts as an inducer for the lac repressor. B. The lac operon would be transcribed less efficiently because acetyl cyclase allows lactose to be directly broken down into glucose and galactose. C. The lac operon would be transcribed less efficiently because acetyl cyclase turns ATP into cAMP, a molecule needed for CAP to bind to the DNA strand to initiate lac transcription. D. The lac operon would be transcribed more efficiently because acetyl cyclase is the name of the repressor that blocks RNA Polymerase II from binding to the DNA strand.

C.

(Hwangbo Q) If Olivia moves the promoter for the lac operon to the region between the beta galactosidase (lacZ) gene and the permease (lacY) gene, which of the following results would be most likely? a) The three genes of the lac operon will be expressed normally. b) RNA polymerase will no longer transcribe permease. c) The operon will still transcribe the lacZ and lacY genes, but the mRNA will not be translated. d) Beta galactosidase will not be produced. e) Beta galactosidase will be continuously produced.

D. ex) From left to right: Repressor gene, Promoter Region(Promoter, then Operator), Lac Z, Lac Y, Lac A. Lac Z is the Beta Galactosidase. If you move the promoter (think of it as the start of a sentence) to the right side of Laz Y, translation will just start there, skipping Lac Z. That's the only important thing being skipped, all the rest of the enzymes will be made.