Bio zoom poll questions 2
In eukaryotes, transcription can occur from DNA contained in the ____. a. 10 nm nucleofilaments b. 30 nm fiber c. 300 nm fiber d. all of the above e. only b and c are true
a. 10 nm nucleofilaments RNA polymerase can only access and transcribe the DNA when it is smaller than 30 nm fiber.
Suppose the brown hair allele (B) is completely dominant to the blond hair allele (b). How many homozygous recessive individuals would the HW principle predict if a population of 200 people have 168 individuals with brown hair. a. 32 b. 72 c. 0.48 d. 0.64
a. 32
The experiment by Weintraub and Groudine showed that _____ cuts genes that are ______ a. DNase; being actively transcribed b. DNA methyl transferase; not being actively transcribed c. RNase; being actively transcribed d. RNA polymerase; not being actively transcribed
a. DNase; being actively transcribed
______ is a regulatory protein that binds to ______ to shut off the transcription from the lac operon a. LacI; lacO operator b. LacI; lacP promoter c. LacZ; lactose d. LacI; lactose
a. LacI; lacO operator
______ are transcription factors that bind to ______ a. activators; enhancers b. enhancers; promoters c. promoters; promoter-proximal elements d. silencers; repressors e initiation region elements; the TATA box
a. activators (type of transcription factor); enhancers (DNA binding site)
The process by which information in DNA is converted to the gene product is called: a. gene expression b. transcription c. translation d. replication e. all of the above
a. gene expression
_____ can cause the frequency of an allele a population to change due to random circumstances or variations over generations a. genetic drift b. genetic flow c. natural selection d. mutations e. nonrandom mating
a. genetic drift (change in allele frequencies of a gene pool due to random meeting of gametes in fertilization)
In E. coli, the gal operon is turned on when galactose is present. However, in its absence the protein GaIR shut is shut off. Thus, the gal operon is said to be _______ regulated a. inducible; negatively regulated b. repressible; negatively regulated c. inducible; positively regulated d. repressible; negatively regulated
a. inducible; negatively regulated (inducible = presence/absence that will turn operon on/off) negatively regulated = absence of galactose, protein is not made
Which of the following statements about conjugation is true? a. it requires direct physical contact between the donor and recipient bacterium b. the recipient creates the sex pilus c. either the F+ or the F- strain can be the recipient d. the donor is always lysed e. both a and c are true
a. it requires direct physical contact between the donor and recipient bacterium
Which of the following is a protein that does not bind directly to a DNA sequence? a. mediator b. activator c. general transcription factor d. repressor
a. mediator
______ is the building block of eukaryotic chromatin. a. nucleosome b. 30 nm nucleofilament c. 300 nm fiber d. 700 nm
a. nucleosome (includes DNA strand wrapped around 8 histones) H1 histone is on the outside
You find a population of 638 individuals where: 6 are DD 115 are Dd 517 are dd Which of the following statements is true about this population in regard to the D gene? a. p = 0.1 b. q = 10.7 c. q = 7.55 d. q = 0.9 e. both a and d are correct
a. p = 0.1
In a particular population, the frequency of the completely dominant allele B is 0.4 and the frequency of the recessive allele b is 0.6. In subsequent generations, an environmental shift leads to increased deaths of individuals with the genotype bb relative to the number of deaths of individuals with at least one copy of the B allele. What would be the likely effect of this environmental shift on the frequency of the B allele? a. the frequency of B would likely increase b. the frequency of B would likely decrease c. the frequency of B would likely stay the same
a. the frequency of B would likely increase
_______ regulation is energetically most efficient but takes the longest for the bacterium to adapt to the environment a. transcriptional b. translational c. posttranscriptional d. both a and b are true
a. trasncriptional
You find a population of 638 individuals where: 6 are DD 115 are Dd 517 are dd Is this population in HW equilibrium for the alleles of the D gene? a. yes b. no c. it cannot be determined without more information
a. yes
In the absence of lactose: a. B-galactosidase is produced b. LacI binds to the lacO+ thereby preventing transcription from the lac operon c. galactoside permease is expressed d. all of the above are true e. only b and c are true
b. LacI binds to the lacO+ therby preventing transcription from the lac operon
Translational control of gene expression: a. affects transcription b. affects protein synthesis or mRNA lifespain c. affects protein activity d. is the quickest of the three modes of gene regulation e. both b and d
b. affects protein synthesis or mRNA lifespan
A bacterium that is _____ means that it is capable of taking up naked extracellular DNA a. transformed b. competent c. conjugated d. mutated
b. competent (recipient cell, naturally or artificially)
Which of the following statements is FALSE? a. the TATA box is upstream of the transcription initiation site b. enhancers are always located upstream of the transcription initiation site c. a eukaryotic transcription factor may bind to the promoter proximal element of several different genes d. silencers are binding sites for repressors
b. enhancers are always located upstream of the transcription initiation site
_____ is the likelihood of an organism to survive and reproduce. a. biological evolution b. fitness c. genetic drift d. gene flow
b. fitness
rhyB refers to the _____, whereas RyhB refers to the _____ a. gene product; gene b. gene; gene product c. gene; mRNA d. mRNA; gene
b. gene; gene product gene = italics gene product/protein = not italicized with upper case letter
A donor strain has the genotype met lys thi+, what must be the genotype of the recipient so that protorophs can be observed? a. met lys thi+ b. met+ lys+ thi c. met lys+ thi d. met lys+ thi+
b. met+ lys+ thi
If you find a population of 1000 individuals where: 0 are EE 698 are Ee 302 are ee Is this population in HW equilibrium for the alleles of the E gene? a. yes b. no c. it cannot be determined without more information
b. no
In the merodiploid strain: I+P+O+Z+Y- I-P+O+Z-Y+ a. does not produce LacI in the absence of the inducer b. produces lacZ and lacY only in the presence of the inducer c. produces lacZ but not lacY in the presence of the inducer d. the lacZ and lacY are produced constitutively
b. produces lacZ and lacY only in the presence of the inducer
In eukaryotic transcription, which of the following events occurs first? a. chromatin decondenses and exposes DNA sequences b. transcription factors bind to promoter-proximal elements c. transcription factors recruit chromatin-remodeling complexes d. RNA polymerase core assembles with sigma to bind to promoter
c. 1. transcription factors recruit chromatin-remodeling complexes (help decondense chromatin) 2. chromatin decondenses and exposes DNA sequences 3. transcription factors bind to promoter-proximal elements 4. RNA polymerase core assembles with sigma to bind to promoter
You find a population of 638 individuals where: 6 are DD 115 are Dd 517 are dd How can we calculate the value for p? a. take the square root of 6 b. take the square root of the frequency of DD since this population must be in equilibrium c. add the genotypic frequency of DD and 1/2 the frequency of Dd
c. add the genotypic frequency of DD and 1/2 the frequency of Dd
In eukaryotes, general transcription factors _____ a. bind to sequences just after the start site of transcription b. inhibit RNA polymerase binding to the promoter and begin transcribing c. bind to other proteins or to the TATA box d. facilitates the binding of ribosomes to the ribosomal binding site
c. bind to other proteins or to the TATA box
An E. Coli strain that has the genotype met lys arg+: a. can synthesize methionine, lysine, and arginine b. can synthesize methionine and lysine but not arginine c. can synthesize arginine but not methionine and lysine d. cannot synthesize methionine, lysine, or arginine
c. can synthesize arginine but not methionine and lysine
Which of the following controls access of RNA polymerase to promoters and genes by controlling the condensation level of the DNA in specific regions? a. Posttranslational control b. Transcriptional control c. Chromatin remodeling d. Translational control
c. chromatin remodeling *something only eukaryotic cells do
A change in allele frequency within a population over time is know as... a. the HW principle b. mutation c. evolution d. natural selection
c. evolution
An operon is a: a. single gene that encodes two or more proteins b. promoter sequence that regulates the transcription of two or more genes c. group of two or more genes that are transcribed from a single promoter d. regulatory gene that codes for a repressor protein
c. group of two or more genes that are transcribed from a single promoter
_____ serves as a platform upon which other proteins assemble to initiate transcription a. repressor b. activator c. mediator d. RNA polymerase IIII e. RNA polymerase II
c. mediator
Male cardinals with bright red feathers that are better able to attract females can lead to biological evolution through _____. a. gene flow b. genetic drift c. nonrandom mating d. natural selection e. mutations
c. nonrandom mating (occurs when individuals are selective about choosing a mate with a preferred trait)
In a population, you find that p = 0.5 and q = 0.5 for one particular gene. What can you conclude from this? a. the observed frequency of the homozygous dominant genotype will be 0.25 b. the observed frequency of the heterozygous genotype will be 0.5 c. the expected frequency of the homozygous recessive genotype is 0.25 d. both a and b are correct
c. the expected frequency of the homozygous recessive genotype is 0.25 * expected (predicted by HW equilibrium)
For a population of organisms, you have found that for gene A, p = 0.7 and q = 0.3. Which of the following would the Hardy Weinberg model predict? a. the frequency of the homozygous dominant genotype would be 0.09 b. the frequency of the homozygous recessive genotype would be 0.49 c. the frequency of the heterozygous genotype would be 0.42 d. only a and c are true e. only b and c are true
c. the frequency of the heterozygous genotype would be 0.42 = 2 (0.7) (0.3) = 0.42
When lactose is imported into the cell: a. the expression of the lac operon is silenced b. the lacI repressor is not expressed c. the lacI repressor becomes inactive d. only the lacZ gene is not expressed, lacY is still expressed e. both b and c are true
c. the lacI repressor becomes inactive
In a particular population you observe 1007 individuals with the genotype GG, 512 individuals with the genotype Gg, and 81 individuals with the genotype gg. What does the HW principle predict as the expected frequency of individuals with the genotype GG? a. 0.23 b. 0.32 c. 0.05 d. 0.62
d. 0.62
You find a population of 638 individuals where: 6 are DD 115 are Dd 517 are dd What are the observed genotypic frequencies a. DD = 0.01 b. Dd = 0.18 c. dd = 0.81 d. all of the above are correct e. it's a trick question, the frequency of DD can never be lower than the frequency of dd since the wild type is always dominant
d. all of the above are correct DD = 0.01 Dd = 0.18 dd = 0.81
In a population, you find that there are: 128 BB individuals 317 Bb individuals 55 bb individuals What can you conclude about this population? a. p = 0.573 b. q = 0.427 c. the frequency of the heterozygous genotype is 0.634 d. all of the above are correct
d. all of the above are correct p = 0.573 q = 0.427 the frequency of the heterozygous genotype is 0.634
An E. Coli strain that has the genotype: met lys arg+ is: a. the wild type strain b. a prototroph c. can grow on minimal medium d. can grow on complete medium e. all of the above
d. can grow on complete medium (strain cannot grow unless it is provided met and lys in the medium)
If a cell of an individual contains the same set of genes, how do these cells become different from each other during development? a. different cell type specific regulatory elements in DNA are selectively lost during development b. differences develop in promoter sequences that lead to different signals being produced by each type of cell c. different cell type specific regulatory elements in DNA are created during development d. differences in extracellular signals received by each cell lead to differences in the types of regulatory proteins present in each cell
d. differences in extracellular signals received by each cell lead to differences in the types of regulatory proteins present in each cell
In a population, you find that p = 0.5 and q = 0.7 for one particular gene. What can you conclude from this? a. the dominant allele is represented by q b. the allele frequencies are not changing over time for this gene c. natural selection must be occurring on this population and it favors the allele of this gene represented by q d. none of the above are correct
d. none of the above are correct (p + q = 1 in Hardy Weinberg equilibrium, frequencies need to add up to 1)
Suppose you find a population where 51 individuals have the dominant phenotype and 49 individuals have the recessive phenotype for a trait that is controlled by a single autosomal gene that shows complete penetrance. What does q equal? a. since the homozygous recessive frequency is 0.49 and since that equals q^2, then q is 0.7 (square root of 0.49). b. since the homozygous recessive individuals have two recessive alleles and the total number of alleles is 200, then q = 2x49/200 = 0.49 c. since p+q=1, and since there are 100 individuals in this population, then q = 100-49/100 = 51/100 = 0.51 d. none of the above are correct
d. none of the above are correct -CANNOT assume that the population is in HW equilibrium (so a and c are incorrect) -b is incorrect because we do not know the # heterozygotes (need to account for the number of recessive alleles within the heterozygotes for a complete answer)
Which of the following statements is FALSE? a. a eukaryotic transcription factor may bind to the promoter-proximal element of several different genes b. various promoter-proximal elements have different sequences that are unique to specific set of genes c. the promoter-proximal element is upstream of +1 d. the TATA box is downstream of the transcription initiation site
d. the TATA box is downstream of the transcription initiation site TATA box = core promoter sequence
A population that is in Hardy-Weinberg equilibrium: a. is experiencing evolution in regard to that particular gene b. is undergoing genetic drift but no mutations are occurring c. is one where mating is not occurring at random d. will not experience a change in allele or genotype frequencies for that particular gene from one generation to the next
d. will not experience a change in allele or genotype frequencies for that particular gene from one generation to the next (no forces acting on the population --> gene is not undergoing biological evolution)
Which of the following will cause a gene to be transcribed more frequently? a. decreased DNA methylation b. increased acetylation of histones c. presence of enhancers d. presence of proximal promoter elements e. all of the above are true
e. all of the above are true decreased DNA methylation (less compact = increases transcription) increased acetylation of histones (less compact = increases transcription) presence of enhancers presence of proximal promoter elements
Which of the following can lead to changes in allele frequency in a population? a. natural selection b. mutation c. gene flow d. none of these can lead to changes in allele frequency in a population e. all of these can lead to changes in allele frequency in a population
e. all of these can lead to changes in allele frequency in a population
If you already know that a population is in HW equilibrium for D and you also know that in a population of 396 individuals that the frequency of dd is 0.36, then what else do you know about this population? a. the frequency of DD must equal 0.64 b. q = 0.6 c. p = 0.4 d. all of the above are correct e. b and c only are correct
e. b and c only are correct q = 0.6 (square root of 0.36 = q^2) p = 0.4 (1-0.6 = 0.4)
A nucleosome is made of: a. DNA b. histones c. transcription factors d. all of the above e. both DNA and histones
e. both DNA and histones
The araBAD operon is turned on in the presence of the sugar arabinose. It is an example of a _________ gene. a. regulated b. inducible c. repressible d. constitutive e. both a and b are true f. both a and c are true
e. both a and b are true regulated (depends on the presence/absence of arabinose) and inducible (presence of arabinose turns the operon on)
You isolate a mutant where the expression from the lac operon is permanently silenced regardless of the presence of lactose. The mutation: a. might be in the promoter of the lac operon b. might produce a nonfunctional LacI protein c. might be in the region of lacI protein that binds to lactose d. all of the above are true e. both a and c are true
e. both a and c are true might be in the promoter of the lac operon might be in the region of lacI protein that binds to lactose
A mutation in the lacZ gene that produces a nonfunctional protein will: a. still import lactose b. still breakdown lactose c. cause the lac operon to be constitutive d. still have the lac operon as inducible e. both a and d are true
e. both a and d are true still import lactose still have the lac operon as inducible
You are studying a novel bacterial pathogen and arrived at the conclusion that it can be transformed. Which of the following experiments support your conclusion? a. when DNase is added, transformants are no longer observed b. when DNase is added, transformants are still observed c. when protease is added, transformants are no longer observed d. when protease is added, transformants are still observed e. both a and d are true
e. both a and d are true when DNase is added, transformants are no longer observed when protease is added, transformants are still observed (DNase breaks down DNA --> no DNA present --> no transformation protease breaks down proteins --> DNA still present --> transformation occurs)
Which of the following is a property of enhancer sequences? a. they can be located far away from the +1 site b. they are orientation independent c. they are binding sites for transcriptional repressors d. all of the above e. only a and b are true
e. only a and b are true they can be located far away from the +1 site they are orientation independent *they are binding sites for transcriptional ACTIVATORS
Which of the following about histones is true? a. H2A, H2B, H3, H4 and H1 are all histone proteins b. they are negatively charged proteins c. involved in DNA packaging d. all of the above e. only a and c are true
e. only a and c are true H2A, H2B, H3, H4 (pairs make up the inside of the nucleosome) and H1 (glues nucleosome together on the outside) are all histone proteins involved in DNA packaging histones have a net positive charge --> allows binding to negatively charged DNA = packaged
Which of the following will result in a more highly compact chromatin? a. decrease DNA methylation b. increase DNA methylation c. decrease histone acetylation d. increase histone acetylation e. only b and c are correct f. only b and d are correct
e. only b and c are correct increase DNA methylation decrease histone acetylation
Biological evolution occurs: a. within individuals b. within populations over time c. when certain alleles of genes increase or decrease fitness of individuals d. all of the above are true e. only b and c are true
e. only b and c are true within populations over time when certain alleles of genes increase or decrease fitness of individuals
______ promoter elements are the binding sites for ______ transcription factors a. proximal; general b. core; general c. proximal; regulatory d. core; regulatory e. only b and c are true
e. only b and c are true core; general proximal; regulatory
A conjugative plasmid: a. contains an oriV b. contains an oriT c. contains genes that code for the pilus proteins d. is transferred as a double stranded DNA molecule to the recipient e. all of the above are true f. a, b, and c are true
f. a, b, and c are true a. contains an oriV b. contains an oriT c. contains genes that code for the pilus proteins
In the bacterial strain with the genotype I+P+Oc Z+Y- a. a functional galactosidase will be produced b. a nonfunctional galactoside permease will be produced c. the holoenzyme can bind to the promoter e. the LacI repressor cannot bind to the operator f. all of the above are true
f. all of the above are true a functional galactosidase will be produced a nonfunctional galactoside permease will be produced the holoenzyme can bind to the promoter the LacI repressor cannot bind to the operator
Transcription factors: a. recognize specific DNA sequences b. form covalent bonds with the center of the base-pairs c. form noncovalent bonds with the edges of base-pairs d. bind only at the minor groove e. all of the above are true f. only a and c are true
f. only a and c are true recognize specific DNA sequences form noncovalent bonds with the edges of base-pairs *binds at major groove NOT minor
In the U-tube experiment, if prototrophs were observed even when the filter was present, this would indicate that formation of prototrophs: a. may occur by conjugation b. may occur by transformation c. may occur by transudction d. does not require direct physical contact between donor and recipient e. all of the above are true f. only b, c, and d are correct
f. only b, c, and d are correct may occur by transformation may occur by transudction does not require direct physical contact between donor and recipient
_____ represents the number of copies of all the alleles of one particular gene that are present in a reproductive population a. the gene pool b. p c. q d. p+q (if only 2 alleles in the population) e. all of the above are true f. only b and c are true g. only a and d are true
g. only a and d are true the gene pool p+q (if only 2 alleles in the population)