Exam 4 (Genetics)
What is the purpose of raising the temperature to 90-95°C at the beginning of each cycle of PCR? a. To separate the double‑stranded DNA b. To renature two single DNA strands c. To extend the primer d. To attach the primer
a
When considering the initiation of transcription, one often finds consensus sequences located in the region of the DNA where RNA polymerase(s) binds. Which of the following is a common consensus sequence? a. TATA b. GGTTC c. any trinucleotide repeat d. TTTTAAAA e. satellite DNAs
a
Where do various forms of posttranscriptional processing in eukaryotes take place on the mRNA? a. alteration of 3′ end b. addition of amino acid sequences c. internal processing d. alteration of 5′5′ end
a, c, & d
Which protein class directly controls many of the metabolic reactions within a cell? a. structural proteins b. enzymes c. repressor proteins d. hydrophilic proteins e. operator proteins
b
Which type of DNA library represents the genes expressed by a given cell at a certain time? a. genomic b. cDNA c. RNA d. protein
b
DNA replication proceeds ________. a. unidirectionally b. dispersively c. semiconservatively d. progressively e. discontinuously
c
What enzyme will replace the R N A primers found in the newly synthesized strand? a. DNA pol III b. DNA pol II c. DNA pol I d. Primase e. ligase
c
Which of the following statements about DNA replication is true? a. Okazaki fragments are DNA fragments synthesized on the leading strand. b. DNA polymerase adds dNTP monomers in the 3′-5′ direction. c. Single‑strand binding proteins stabilize the open conformation of the unwound DNA. d. DNA gyrase unwinds the DNA double helix.
c
The protein responsible for the initial step in unwinding the DNA helix during replication of the bacterial chromosome is coded for by the ________ gene. a. gyrA b. polA c. dnaE d. dnaA e. polB
d
What is the name of the protein that helps fold other proteins into their final and functional form? a. proteasomes b. ubiquitin c. collagen d. chaperone e. flippase
d
Which of the following molecules is not required for a PCR reaction? a. DNTPs b. DNA c. Primer d. Ligase
d
When performing a sequencing reaction using Sanger sequencing, which ddNTPs must be included in the reaction? a. ddATP b. ddTTP c. ddGTP d. ddCTP e. all four ddNTPs must be present
e
A knock-out mouse is made with respect to the PFKL gene, and this mouse is now described as which of the following? a. a loss-of-function PFKL mouse b. a gain-of-function PFKL mouse c. a retention-of-function PFKL mouse d. an enhancement-of-function PFKL mouse
a
A mutation in EF-Tu would have a DIRECT effect on which part of translation? a. The next tRNA would not be able to enter the A site of the ribosome. b. The small and large subunits would not bind. c. The peptide bond formation would be blocked. d. The polypeptide would form, but translation termination would be blocked. e. Translocation would be directly blocked.
a
A particular mRNA is 300 nucleotides long. If a mutation in the middle of the sequence changed a codon from a AAA to a UAA then what would be a reasonable prediction? a. The protein coded by this mRNA would be shorter. b. The protein coded by this mRNA would be the same size. c. The protein coded by this mRNA would kill the cell. d. The protein coded by this mRNA would be longer. e. The protein coded by this mRNA would not form due to a failure in initiation.
a
A plasmid contains a multiple cloning site inside the coding region of the lacZ gene and also contains an ampicillin resistance gene at a separate locus. When cells are transformed with a successfully recombinant plasmid containing a piece of DNA cloned into the multiple cloning site, what color will the colonies be when grown on an agar plate containing ampicillin and X-gal? a. white b. clear c. colonies will not grow d. green e. blue
a
Agarose gels separate DNA fragments based on what property? a. size of the fragment b. amount of agarose in the DNA c. charge of the DNA molecule d. amount of adenine bases in the sequence
a
An mRNA that is being produced comes off of the ________. a. template strand in both bacteria and eukaryotes b. template strand in bacteria and the coding strand in eukaryotes c. coding strand in both bacteria and eukaryotes d. coding strand in bacteria and the template strand in eukaryotes e. coding or template strand in both bacteria and eukaryotes depending upon the species
a
Assuming that an amino acid sequence is 250 amino acids long, how many different molecules, each with a unique sequence, could be formed? a. 20^250 b. 250 x 20 x 2 c. 250^20 d. 250 x 20
a
Assuming the genetic code is a triplet, what effect would the addition or loss of two nucleotides have on the reading frame? a. It will change the reading frame. b. It will change the reading frame and result in the addition or loss of amino acids in the resulting protein. c. It will have no effect on the reading frame. d. It will have no effect on the reading frame, but will result in the addition or loss of amino acids in the resulting protein.
a
BamHI cuts the sequence 5′ G|GATCC 3′. Which of the following sequences would not be recognized by this enzyme? a. 3′ TCTTAAG 5′ b. 5′ AGCGGATCC 3′ c. 3′ CCTAGGATC 5′ d. 5′ AGGATCCGTA 3′
a
Creutzfeldt-Jakob, Huntington, Alzheimer, and Parkinson disease are all characterized with which part of protein synthesis? a. protein folding b. elongation c. N-terminal modification d. initiation e. termination
a
DNA replication in eukaryotes ________. a. initiates at multiple origins b. utilizes a single type of DNA polymerase c. takes place multiple times per cell cycle d. occurs without the need of a primer e. synthesizes DNA approximately 25 times faster than in prokaryotes
a
DNA sequencing by the Sanger method employs which of the following for chain termination? a. Dideoxynucleotides b. Dinucleotides c. Ribonucleotides d. Deoxynucleotides
a
Different sets of human hemoglobins are found at different times in development. a. true b. false
a
Each aminoacyl tRNA synthetase is specific for one amino acid and a small number of tRNAs. a. true b. false
a
If there were six bases in D N A and still only 20 amino acids, how long would a codon need to be in order to specify an amino acid? a. 2 bases b. 3 bases c. 4 bases d. 6 bases e. 20 bases
a
In eukaryotic cells, transcription occurs in the nucleus, and translation occurs in the cytoplasm. a. true b. false
a
In the Meselson-Stahl experiment, if D N A had been replicated conservatively, after two rounds of replication, there would be _____. a. one old, heavy band and one new, light band b. one "hybrid" band c. one "hybrid" band and one new, light band d. one "hybrid" band and one old, heavy band e. one old, heavy band, one new, light band, and one "hybrid" band
a
In the Meselson-Stahl experiment, which mode of replication was eliminated based on data derived after one generation of replication? a.conservative b. dispersive c. semiconservative d. none of the modes
a
Modular portions of a protein that fold into stable conformations with specific functional capabilities are referred to as ________. a. protein domains b. protein subunits c. protein secondary structures d. protein chaperones e. protein quaternary structures
a
Phage λ can carry larger DNA fragments than plasmids. a. true b. false
a
Reading the RNA sequences in a 5' to 3' direction, a base at the first position of an anticodon on the tRNA would pair with a base at the ________ position of the mRNA. a. third b. first c. second
a
Suppose that in the use of polynucleotide phosphorylase, nucleotides A and C are added in a ratio of 1A:5C. What is the probability that an AAA sequence will occur? a. 1/216 b. 1/432 c. 1/36 d. 1/125 e. 1/64 f. 1/27
a
The activity of ________ would be quickly undone in the absence of single-stranded binding protein. a. DNA helicase b. primase c. DNA ligase d. DNA polymerase I e. DNA polymerase III
a
The amount of DNA that is replicated from a single origin of replication is referred to as a(n) ________. a. replicon b. primer c. ori d. Okazaki fragment e. fork
a
The experiments that deciphered the genetic code used an enzyme called polynucleotide phosphorylase. If researchers added this enzyme to a large quantity of only guanine (G) ribonucleoside diphosphates then a RNA molecule would be produced that would code for which amino acid? a. glycine (gly) b. lysine (lys) c. arginine (arg) d. phenylalanine (phe) e. proline (pro)
a
The finding that some phage genes have multiple initiation sites is evidence against what characteristic of the genetic code? a. The genetic code is nonoverlapping. b. The genetic code is a triplet code. c. The genetic code is commaless. d. The genetic code is universal. e. The genetic code is unambiguous.
a
The genomics era began with the development of which of the following? a. whole-genome sequencing b. PCR c. third-generation sequencing d. whole-transcriptome sequencing
a
The nuclear genetic code is considered universal with a few exceptions. Some of these exceptions are found when comparing the nuclear genetic code of humans to what? a. human mitochondrial genetic code b. chimpanzee's genetic code c. bacterial genetic code d. phage M2 genetic code e. angiosperm's genetic code
a
The sigma subunit of bacterial R N A polymerase _____. a. binds to a bacterial gene's promoter b. is required for R N A polymerization c. is required for termination of transcription d. is required for ribosomal binding
a
What is the definition of a clone? a. an identical copy of a DNA molecule, a cell, or an organism b. a non-identical DNA molecule produced by recombinant DNA technology c. a circular DNA molecule that is able to replicate by itself d. a new combination of DNA molecules that is not found naturally
a
What is the first molecule in the biochemical pathway? a. succinate b. malate c. fumarate d. oxaloacetate
a
What is the order of mutations? a. 141, 162,136 b. 136, 141, 162 c. 162, 136, 141 d. 141, 136, 162 e. 162, 141, 136 f. 136, 162, 141
a
Which DNA polymerase is mainly responsible for genome replication in E. coli? a. DNA polymerase III b. DNA polymerase α c. DNA polymerase I d. DNA polymerase II
a
Which class of protein functions primarily by lowering the energy of activation during a reaction? a. enzymes b. heat-shock proteins c. prions d. chaperones
a
Which is the following is not a necessary feature of a good cloning vector? a. The ability to carry DNA fragments of up to 200 k b b. The ability to be replicated c. Restriction site(s) for the insertion of a foreign D N A fragment d. selectable marker gene e. The ability to be isolated from the host cell
a
Which level of protein structure do beta-pleated sheets and alpha helices represent? a. secondary b. tertiary c. primary d. quaternary
a
Which of the following is never found in the A-site of the ribosome? a. initiator tRNAmet b. release factor c. aminoacyl tRNA d. tRNA bearing the growing e. polypeptide chain
a
Which of the following lists steps of mRNA production in eukaryotes in the correct order? a. Transcription, 5' cap addition, addition of poly-A tail, exon splicing, passage through nuclear membrane b. Transcription, addition of poly-A tail, 5' cap addition, exon splicing, passage through nuclear membrane c. Transcription, 5' cap addition, addition of poly-A tail, passage through nuclear membrane, exon splicing d. 5' cap addition, addition of poly-A tail, exon splicing, passage through nuclear membrane, transcription
a
Which of the following statements is true regarding Okazaki fragments? a. They are short fragments of DNA synthesized from RNA primers on the lagging strand. b. They are synthesized by ligase. c. They are short fragments of RNA on the leading strand. d. They add nucleotides to the elongating DNA.
a
Would you predict this change to have the same effect? a. This change would be predicted to have less effect compared to the change of the amino acid from glutamic acid to valine. b. This change would be predicted to have more effect compared to the change of the amino acid from glutamic acid to valine. c. This change would be predicted to have the same effect compared to the change of the amino acid from glutamic acid to valine. d. It is impossible to predict the effect of a single nucleotide without proper genetic sequencing.
a
tRNAs___________ a. have double-stranded regions b. can be recognized by several aminoacyl-t R N A synthetases c. can carry more than one type of amino acid per molecule d. consist of two subunits e. contain unusual nucleotides, encoded by genes with nonstandard bases
a
Describe the role of 15N in the Meselson-Stahl experiment. (3 answers) a. Labeling the pool of nitrogenous bases of the DNA of E. coli with the heavy isotope 15N labels allows old DNA to be followed. b. Labeling the pool of nitrogenous bases of the RNA with 15N allows for the detection of newly synthesized DNA. c. Electrophoresis enables the separation of labeled DNA and estimates the amounts of DNA at various times during the experiment. d. A comparison of the density of DNA samples at various times in the experiment allows an estimation of amounts of old and new DNA . e. Medium containing 15N is more nutritious, so growing the cells in such medium allows results to be obtained in a shorter time. f. Growing the cells for many generations in medium containing 15N and transferring to 14N medium allows for the detection of new DNA.
a, d, f
A PCR was designed to clone a DNA sequence of 1.5 kb. When the products were run on an agarose gel, there was a smear of bands ranging from 1.5 kb to 6 kb. Which of the following is a reason for this result? a. the polymerase denatured b. one of the primers did not bind c. the polymerase overran the reverse primer d. the thermocycler malfunctioned
b
A particular mRNA makes a protein that has an unformylated methionine as its first amino acid. Did this mRNA come from a bacterial or a eukaryotic cell? a. Bacterial cell. Bacterial mRNA code for proteins starts with an unformylated methionine whereas eukaryotic mRNA code for proteins starts with a formylated methionine. b. Eukaryotic cell. Eukaryotic mRNA code for proteins starts with an unformylated methionine whereas bacterial mRNA code for proteins starts with a formylated methionine. c. The cell cannot be determined, because both eukaryotic and bacterial mRNA code for proteins may start with a formylated or unformylate methionine. d. Neither bacterial nor eukariotic cell, because no mRNA code for proteins starts with an unformylated methionine.
b
After observing the results of one round of replication, the scientists obtained results from a second round. The purpose of one additional round of replication was to _______. a. confirm that replication is conservative b. distinguish between semi-conservative and dispersive replication c. distinguish between conservative and semi-conservative replication d. distinguish between conservative and dispersive replication
b
All EXCEPT which of the following are related to telomeres? a. telomerase enzyme b. found in eukaryotes and prokaryotes c. links to the aging process d. short tandem repeats located at the ends of telomeres
b
All known bacterial D N A polymerases _____. a. can initiate D N A chain synthesis b. have 5′ to 3′ polymerization activity c. have 5′ to 3′ exonuclease activity d. have 3′ to 5′ polymerization activity e. all of the above
b
An intron is a section of ________. a. DNA that is removed during DNA processing b. RNA that is removed during RNA processing c. carbohydrate that serves as a signal for RNA transport d. protein that is clipped out posttranslationally e. transfer RNA that binds to the anticodon
b
Assume that a plasmid (circular) is 2800 base pairs in length and has restriction sites for EcoRI at the following locations: 400, 700, 1400, and 2600. Give the expected sizes of the restriction fragments following complete digestion with EcoRI. a. 700, 400, 1400, 2600 b. 300, 600, 700, 1200 c. 400, 1200, 1600 d. 200, 400, 700, 1200 e. 300, 700, 2200
b
DNA polymerase III adds nucleotides ________. a. in the place of the primer RNA after it is removed b. to the 3' end of the RNA primer c. to internal sites in the DNA template d. to the 5' end of the RNA primer e. to both ends of the RNA primer
b
Due to the wobble hypothesis, which position in the codon, if changed to a different nucleotide, would be least likely to cause a change in the amino acid encoded? a. first nucleotide of the codon b. third nucleotide of the codon c. any nucleotide of the codon d. second nucleotide of the codon e. either the first or second nucleotide of the codon.
b
During eukaryotic translation initiation, the _____ serves a role analogous to the Shine-Delgarno sequence in bacteria. a. poly-A tail b. 7-methylguanosine (m7G) cap c. initiator d. TATA box
b
During initiation in bacterial translation, a particular mutation causes the premature binding of the large ribosome subunit to the small ribosome subunit. Which component of initiation is not working properly? a. Shine-Dalgarno sequence on the mRNA b. IF3 c. IF1 d. Ribosome's E site e. IF2
b
Identify a classic experiment that used autoradiography to determine the replicative nature of DNA in eukaryotes. a. The Meselson-Stahl (1958) experiment used 15N-containing molecules. b. The Taylor, Woods, and Hughes (1957) experiment used 3H-thymidine. c. The Okazaki (1968) experiment used small fragments containing RNA primers. d. The Kornberg (1957) experiment used four radiolabeled deoxyribonucleoside triphosphates (dNTPs).
b
Identify a difference between the RNA polymerases of eukaryotes and prokaryotes. a. In eukaryotes, three polymerases (α, β, and δ) have been identified; only one has been described in prokaryotes. b. In eukaryotes, three polymerases (I, II, and III) have been identified; only one has been described in prokaryotes. c. In prokaryotes, three polymerases (α, β, and δ) have been identified; only one has been described in eukaryotes. d. In prokaryotes, three polymerases (I, II, and III) have been identified; only one has been described in eukaryotes.
b
If one wishes to clone a gene using typical restriction endonucleases, how does the restriction endonuclease identify the appropriate cut sites in the genome? a. The endonuclease cuts randomly in the genome. b. The endonuclease identifies its specific recognition sequence. c. The endonuclease recognizes the gene of interest. d. The endonuclease cannot identify the cut sites.
b
In prokaryotes, which component must disassociate to allow for elongation of the transcriptional complex? a. RNA polymerase b. sigma subunit c. rho d. none of the above
b
Individuals with phenylketonuria cannot convert phenylalanine to tyrosine. Why don't these individuals exhibit a deficiency of tyrosine? a. Phenylalanine and tyrosine are needed in only small amounts. b. Both phenylalanine and tyrosine can be obtained from the diet. c. Both phenylalanine and tyrosine are nonessential amino acids. d. Tyrosine is a nonessential amino acid.
b
Next, you would like study the gene that you ligated into the plasmid in Part B. From that experiment, which colonies should you select to culture for further experimentation? a. white colonies that grew on complete media b. white colonies that grew on complete media + ampicillin + X-gal c. blue colonies that grew on complete media + ampicillin + X-gal d. white colonies that grew on complete media + ampicillin
b
Northern blots are used to study what type of molecule? a. Proteins b. RNA c. RNA and proteins d. DNA
b
Recognition sequences for restriction enzymes possess the unique quality of being the same when read 5 to 3 on either strand. What is this property called? a. consensus sequence b. palindromic sequence c. gene sequencere d. combination sequence e. origin sequence
b
Restriction endonucleases cut DNA at specific recognition sequences and then bond two strands covalently with the same "sticky ends." a. true b. false
b
Restriction enzymes are used in all of the following molecular biology techniques EXCEPT __________. a. cloning DNA into vectors b. PCR c. mapping studies d.creating DNA libraries
b
Substitution RNA editing is known to involve either C-to-U or A-to-I conversions. What common chemical event accounts for each? a. Both cases involve the removal of an OHOH group. b. Both cases involve the removal of an NH2NH2 group. c. Both cases involve the removal of one group, but in one case it is an NH2NH2 group, and in other - an OHOH group
b
The Meselson and Stahl's experiment provided conclusive evidence for the semiconservative replication of DNA in E. coli . What pattern of bands would occur in a CsCl gradient for conservative replication? a. After one generation in the 14N, there would be three bands, one heavy, one intermediate, and one light. After the second generation in the 14N, there would also be three bands, one heavy, one intermediate, and one light. b. After one generation in the 14N, there would be two bands, one heavy and one light (no intermediate). After the second generation in the 14N, there would also be two bands, one heavy and one light (no intermediate). c. After one generation in the 14N, there would be two bands, one heavy and one light (no intermediate). After the second generation in the 14N, there would be three bands, one heavy, one intermediate, and one light. d. After one generation in the 14N, there would be one heavy band (no intermediate and no light). After the second generation in the 14N, there would be three bands, one heavy, one intermediate, and one light.
b
The chromosome of phage φX174 encodes nine proteins consisting of a total of more than 2300 amino acids, even though the size of its genome predicts that it should be able to code for only 1795 amino acids. The reason for this discrepancy is a. Alternative splicing b. Overlapping reading frames c. Frameshift mutations d. Enhancers
b
The data obtained from the Meselson-Stahl experiment after one generation of replication eliminated the dispersive model of DNA replication. a. true b. false
b
The enzyme EF‑Tu catalyzes the formation of a peptide bond between the amino acid held by the tRNA in the A site and the elongating amino acid chain held by the tRNA in the P site. a. true b. false
b
The genetic code is _________, meaning that an amino acid may be encoded by more than one codon. a. unambiguous b. degenerate c. commaless d. universal e. nonoverlapping
b
The genetic code is fairly consistent among all organisms. The term often used to describe such consistency in the code is ________. a. exceptional b. universal c. trans-specific d. overlapping d. none of the above
b
The protein shown below provides an example of which level of protein folding? a. primary b. quaternary c. secondary d. tertiary e. pentenary
b
The thermostability of Taq polymerase is required during the annealing phase of PCR. a. true b. false
b
Transformation of cells using the technique of heat shock requires which of the following? a. brief electric shock b. the use of calcium and brief exposure to elevated temperature c. the use of calcium ions d. the use of zinc ions e. brief exposure to elevated temperature
b
Translation in bacteria is directly dependent on all of the following associations except _______. a. complementary base pairing between mRNA and rRNA b. complementary base pairing between mRNA and DNA c. complementary base pairing between mRNA and tRNA d. association of the 30S and the 50S ribosomal subunits
b
What activity provides D N A pol III the ability to proofread? a. DNA pol III has 5′→3′ exonuclease activity. b. DNA pol III has 3′→5′ exonuclease activity. c. DNA pol III has exonuclease activity in both the 5′→3′ and 3′→5′ directions. d. DNA pol III has polymerase activity in the 5′→3′ and 3′→5′ directions. e. The sliding clamp activity.
b
What is a probe in molecular biology? a. an instrument used to manipulate cells in culture b. a DNA or an RNA molecule used in hybridization reactions c. a type of vector system d. Probes are not used in molecular biology.
b
What is the last component incorporated in the process of translational initiation? a. small ribosomal subunit b. large ribosomal subunit c. initiation factor(s) d. initiator tRNAmet
b
What is the proper order of molecules in this biochemical pathway? a. succinate, malate, fumarate, oxaloacetate b. succinate, fumarate, malate, oxaloacetate
b
What is the role of general transcription factors (G T Fs)? a. GTFs bind to enhancers or silencers and regulate transcription b. GTFs bind to the core promoter and allow transcriptional initiation c. GTFs are cis-acting regulatory sequences d. GTFs regulate the length of the m R N A e. GTFs are part of the R N A polymerase II holoenzyme, and control transcription initiation
b
What was the significance of the polA1 mutation? a. It was used to pinpoint the region of the chromosome that contains the gene determining the rate of DNA synthesis in bacteria. b. It was instrumental in demonstrating that DNA polymerase II activity is not necessary for in vivo replication. c. It was instrumental in estimating the rate of DNA synthesis in bacteria. d. It was used to determine the functions of different subunits of DNA polymerase I.
b
When a peptide bond is formed between two amino acids, one is attached to the tRNA occupying the P site and the other _______. a. is attached to the tRNA occupying the E site b. is attached to the tRNA occupying the A site c. is free in the cytoplasm d. is attached through hydrogen bonds to the mRNA
b
When scientists were attempting to determine the structure of the genetic code, Crick and coworkers found that when three base additions or three base deletions occurred in a single gene, the wild-type phenotype was sometimes restored. These data supported the hypothesis that ________. a. AUG is the initiating triplet b. the code is triplet c. there are three amino acids per base d. the code contains internal punctuation e. the code is overlapping
b
Which cluster of terms accurately reflects the nature of DNA replication in prokaryotes? a. random point of initiation, bidirectional, semiconservative b. fixed point of initiation, bidirectional, semiconservative c. fixed point of initiation, bidirectional, conservative d. random point of initiation, unidirectional, semiconservative e. fixed point of initiation, unidirectional, conservative
b
Which compound accumulates in the metabolic disorder alkaptonuria? a. Phenylalanine b. Homogentisic acid c. Tyrosine d. Phenylalanine hydroxylase
b
Which of the following describes a "knock-out" organism? a. An organism that is capable of out-competing another organism. b. An organism that is negative for alleles coding a gene of interest. c. An organism that is positive for alleles coding a gene of interest. d. An organism that loses consciousness randomly.
b
Which of the following elements is not found in a plasmid? a. Antibiotic resistance b. Lambda arms c. lacZ gene d. Polylinker
b
Which of the following is true regarding the genetic code? a. The genetic code is ambiguous. b. The genetic code is degenerate. c. The genetic code has three start codons and one stop codon. d. The genetic code is considered to not be universal. e. The genetic code is overlapping.
b
You irradiate spores of Neurospora to induce mutations. While normal spores can grow on minimal medium, you isolate one that cannot. When you inoculate supplemented medium with spores from this mutant, you observe the following results. From this, you can conclude your mutant is a. auxotrophic for amino acids b. auxotrophic for purines c. auxotrophic for pyrimidines d. auxotrophic for adenine e. auxotrophic for pyrimidines, amino acids, and adenine
b
Which of the following best describe(s) the function of the 5' mRNA cap? a. To provide a binding site for poly(A) polymerase b. To protect the transcript from degradation c. Termination of transcription d. It provides a site for ribosome binding in the cytoplasm.
b & d
Which statements are true? a. Intrinsic termination in prokaryotes occurs when the rho termination factor interacts with the growing RNA transcript. b. Since prokaryotes lack a nucleus, translation can begin before the transcript is fully transcribed. c. Eukaryotic RNA polymerase II requires general transcription factors for initiation of transcription. d. Three different RNA polymerases in eukaryotes transcribe different classes of genes.
b, c, & d
What are four ways that mRNA can be modified? Select the four сorrect answers. a. adding a polyadenylation tail to the 5′ end b. adding a modified guanine to the 5′ end c. splicing of introns d. adding a modified guanine to the 3′ end e. adding a polyadenylation tail to the 3′ end f. RNA editing
b, c, e, & f
A DNA fragment is introduced into the lacZ gene of a plasmid, which also contains a tetracycline resistance gene. What is the appearance of bacteria transformed with this plasmid if they are spread on plates containing tetracycline and Xgal? a. White colonies that are sensitive to tetracycline b. Blue colonies that are sensitive to tetracycline c. White colonies that are resistant to tetracycline d. Blue colonies that are resistant to tetracycline
c
A nonsense mutation is a mutation _____. a. that alters the reading frame b. that changes the amino acid sequence of the gene product c. that creates a termination codon d. in a t R N A gene that allows it to recognize a termination codon e. that allows a ribosome to bypass termination codons
c
A probe with the sequence 5'-A-T-G-C-C-A-G-T-3' will serve as a probe for which sequence? a. 3'-A-C-T-G-G-C-A-T-3' b. 3'-A-T-G-C-C-A-G-T-5' c. 3'-T-A-C-G-G-T-C-A-5' d. 3'-T-G-S-C-C-G-T-A-5'
c
After ONE round of DNA replication in Meselson and Stahl's classic experiment, ________. a. the dispersive model was conclusively proven to be an inaccurate model b. the semiconservative model was conclusively proven to be the accurate model c. the conservative model was conclusively proven to be an inaccurate model d. both the conservative and the semiconservative models were still possibilities e. all three models of replication were still possibilities
c
All of the following are involved in the process of tRNA charging EXCEPT __________. a. aminoacyl tRNA synthetase b. amino acids c. rRNA d. ATP
c
All of the following may occur during posttranslational modification of a protein EXCEPT __________. a. removal of N-terminal amino acid b. addition of phosphate groups c. removal of introns d. addition of metals to create tertiary or quaternary structures
c
Assume that a base addition occurs early in the coding region of a gene. Is the protein product of this gene expected to have MORE or FEWER altered amino acids compared with the original gene with a base deletion late in the coding region? a. Adding a base early in the coding region would change fewer amino acids since an addition of a base pair has less impact on amino acid sequence than a deletion does. b. Adding a base early in the coding region would change fewer amino acids since only a deletion of a base pair would change every codon following the deletion. c. Adding a base early in the coding region would change more amino acids since an addition or deletion of a base pair would change every codon after the addition or deletion. d. Adding a base early in the coding region would change more amino acids since only an addition of a base pair would change every codon following the addition.
c
At which site does the charged initiator tRNA bind during protein synthesis? a. T site b. E site c. P site d. A site
c
By their experimentation using the Neurospora fungus, Beadle and Tatum were able to propose the far-reaching hypothesis that ________. a. prototrophs will grow only if provided with nutritional supplements b. more than one codon can specify a given amino acid c. the role of a specific gene is to produce a specific enzyme d. genetic recombination occurred in Neurospora e. several different enzymes may be involved in the same step in a biochemical pathway
c
DNA fragments cut by restriction enzymes can form two types of ends. What are these ends called? a. ligase and blunt ends b. salvage and sharp ends c. sticky and blunt ends d. tails and heads
c
During DNA replication, ________ are 1000-2000 nucleotide long strands synthesized on the ________ strand to maintain the ________ of replication. a. Okazaki fragments; leading; semidiscontinuity b. primers; leading; discontinuity c. Okazaki fragments; lagging; bidirectionality d. Okazaki fragments; leading; accuracy e. primers; lagging; continuity
c
During the elongation phase of translation, charged t R N A s enter the ribosome at the ______. a. E site b. P site c. A site d. Shine-Delgarno site e. G site
c
Eukaryotic transcription is different than bacterial transcription because eukaryotic transcription ________. a. only requires one RNA polymerase b. does not require the mRNA to be modified c. requires the uncoiling of the chromatin fiber d. does not require general transcription factors to initiate transcription e. occurs in the cytoplasm
c
High throughput sequencing takes advantage of automated reading of sequencing data. Which of the following assists in automating the sequencing readout? a. fluorescently tagged dNTPs b. radioactive dNTPs c. fluorescently tagged ddNTPs d. radioactive ddNTPs
c
How many different codons code for amino acids? a. 3 b. 20 c. 61 d. 64
c
Identify what is meant by the term autoradiography. a. Autoradiography is a technique that use antibodies to detect structures inside a cell. b. Autoradiography is a technique that allows molecules of nucleic acids to be detected within a cell. c. Autoradiography is a technique that allows an isotope to be detected within a cell. d. Autoradiography is a technique that allows to detect structures inside a cell with the use a fluorescent label.
c
In 1964, Nirenberg and Leder used the triplet binding assay to determine specific codon assignments. A complex of which of the following components was trapped in the nitrocellulose filter? a. ribosomes and DNA b. sense and antisense strands of DNA c. charged tRNA, RNA triplet, and ribosome d. free tRNAs e. uncharged tRNAs and ribosomes
c
Is there any role for an R N A polymerase in D N A replication? a. No, only D N A polymerases function in D N A replication. b. Yes, in order to synthesize m R N A. c. Yes, to generate primers. d. Yes, to synthesize R N A that will bind to and keep the two D N A strands unwound. e. Yes, in eukaryotes an R N A polymerase functions in telomere maintenance.
c
It has been recently determined that the gene for Duchenne muscular dystrophy (DMD) is more than 2000 kb (kilobases) in length; however, the mRNA produced by this gene is only about 14 kb long. What is a likely cause of this discrepancy? a. When the mRNA is produced, it is highly folded and therefore less long. b. The DNA represents a double-stranded structure, whereas the RNA is single-stranded. c. The introns have been spliced out during mRNA processing. d. The exons have been spliced out during mRNA processing. e. There are more amino acids coded for by the DNA than by the mRNA.
c
Nucleic acid blotting is commonly used in molecular biology. Northern blotting is used to detect the presence of which type of nucleic acid? a. transfer ribonucleic acids b. deoxyribonucleic acids c. ribonucleic acids d. triphosphate nucleic acids e. unnatural nucleic acids
c
Nutritional mutants in Neurospora can be "cured" by treating the medium with substances in the defective metabolic pathway. What determines whether the mutant strain (auxotroph) is "cured" by a particular substance? a. The first substance in the biochemical pathway needs to be added. b. The substance to be added depends on other substances in the media. c. The substance needs to be added after the metabolic block in the biochemical pathway. d. The substance needs to be added before the metabolic block in the biochemical pathway.
c
Once elongation is underway, tRNAs involved in the process occupy a series of sites on the complexed ribosome. The occupation of sites occurs in the following order. a. A Site, P Site, E Site, S Site b. P Site, E Site, A Site c. A Site, P Site, E Site d. A Site, S Site, E Site
c
Protospacer adjacent motifs, PAMs, allow bacteria to do which of the following? a. recognize and integrate foreign DNA b. recognize and digest their own DNA c. recognize and digest foreign DNA d. recognize proper spacing for bacterial transcription initiation
c
Sanger sequencing is based on the order in which ddNTPs are added to a growing polynucleotide. Why are ddNTPs integral to the Sanger sequencing method? a. They have a 3 hydroxyl that allows for extension of the polynucleotide. b. They have a 2 hydroxyl that allows for extension of the polynucleotide. c. They do not have a 3 hydroxyl, which does not allow the extension of the polynucleotide. d. They do not have a 2 hydroxyl, which does not allow the extension of the polynucleotide.
c
Small nuclear RNAs (snRNAs) are rich in uridine residues and are involved with: a. self-slicing RNAs b. rho dependent transcription termination c. excision of introns via spliceosomes d. attachment of sigma subunit to the bacterial promoter
c
The following are four processes common to most cloning experiments: i)transforming bacteria ii)plating bacteria on selective medium iii)cutting DNA with restriction endonucleases iv)ligating DNA fragments Place the components of this list in the order in which they would most likely occur during a cloning experiment. a.I I , ii, iii, iv b. iv, i, iii, iii c. ii, iv, i, ii d. ii, i, iv, iii e. ii, iii, i, iv
c
The following is the order of steps when preparing a Southern Blot: a. Extract DNA, transfer DNA fragments to membrane via blotting, hybridize membrane with probe, expose membrane to X ray film, develop Xray and observe band patterns b. Extract DNA, digest DNA with restriction enzymes, transfer DNA fragments to membrane via blotting, run a gel, hybridize gel with probe, expose gel to X ray film, develop Xray and observe band patterns c. Extract DNA, digest DNA with restriction enzymes, run a gel, transfer DNA fragments to membrane via blotting, hybridize membrane with probe, expose membrane to X ray film, develop Xray and observe band patterns d. Extract DNA, run a gel, hybridize membrane with probe, expose membrane to X ray film, develop Xray and observe band patterns
c
The type of RNA modification that requires guide RNAs is ________. a. addition of the 3 polyadenylated tail b. addition of the 7-methylguanosine cap to the 5 end c. RNA editing d. removal of introns e. splicing together of exons
c
The wobble hypothesis predicts that codons coding for the same amino acid _____. a. may differ at the first position b. may differ at the second position c. may differ at the third position d. may differ at the first two positions e. may differ at all three positions
c
What effect would the addition or loss of three, six, or nine nucleotides have on the reading frame? a. It will change the reading frame. b. It will have no effect on the reading frame. c. It will have no effect on the reading frame, but will result in the addition or loss of amino acids in the resulting protein. d. It will change the reading frame and result in the addition or loss of amino acids in the resulting protein.
c
What event occurs during translocation? a. The two ribosomal subunits join to form a complex. b. The polypeptide is cleaved from the terminal tRNA. c. mRNA shifts in the 5' direction along the ribosome. d. Amino acids are added to the polypeptide chain.
c
What is meant by a gene knockout? a. The synthesis of gene DNA using RNA as a template. b. The insertion of several six-nucleotide repeats in the gene sequence in order to study the structure of the encoded protein. c. The designed loss of a specific gene in order to study its function. d. The deletion of a gene in order to study the structure of the encoded protein.
c
What is the initiator triplet in both bacteria and eukaryotes? What amino acid is recruited by this triplet? a. UAA, UGA, or UAG; arginine b. UAA, UGA, or UAG; no amino acid called in c. AUG; methionine d. AUG; arginine e. UAA, UGA, or UAG; methionine
c
What is the last molecule in the biochemical pathway? a. fumarate b. succinate c. oxaloacetate d. malate
c
What is the name given to the three bases in a messenger RNA that bind to the anticodon of tRNA to specify an amino acid placement in a protein? a. rho b. anti-anticodon c. codon d. protein e. cistron
c
What signals termination of translation in bacteria? a. EF-Tu and EF-G b. the stop amino acid is attached to the growing peptide chain c. RF1 and RF2 d. a tRNA specific to the stop codon enters the ribosome's A site e. ribozymes
c
When a 5-kb circular plasmid is digested with a restriction enzyme that has three recognition sites on the plasmid, how many bands can be visualized on an agarose gel? a. 1 b. 2 c. 3 d. 4
c
Which activity of E. coli DNA polymerase I is responsible for proofreading the newly synthesized DNA? a. 3' to 5' endonuclease b. 5' to 3' polymerase c. 3' to 5'; exonuclease d. 5' to 3' exonuclease
c
Which enzyme catalyzes the addition of nucleotides to a growing DNA chain? a. telomerase b. primase c. DNA polymerase d. helicase
c
Which features make yeast artificial chromosomes (YACs) an excellent cloning tool? a. YACs are large but low copy number plasmids that can accept DNA inserts up to 300-kb range. b. Eukaryotic genes are relatively small. Cloning into a YAC allows for the function and the structure of these genes to be studied. c. YACs have telomeres at each end, ORI and centromere d. The YAC allows for the expression of bacterial genes.
c
Which of the following intron groups is matched appropriately with a true statement? a. Spliceosomal introns are removed using the catalytic ability of the intron itself. b. Group I introns are removed from rRNAs that are found in mitochondria and chloroplasts. c. Spliceosomal introns are removed using large protein-based enzyme complexes. d. Group I introns are removed from rRNAs using large protein-based enzyme complexes. e. Group II introns are removed from mRNA in mammals.
c
Which of the following is characteristic of transcription in eukaryotes but not in prokaryotes? a. A 3' untranslated trailer sequenceA b. 5' untranslated leader sequence c. Exon splicing catalyzed by the spliceosome d. A single transcript may be transcribed and translated simultaneously.
c
Which of the following statements about a Neurospora valine auxotroph is true? a. The cells cannot grow on complete medium. b. The cells can grow on minimal medium + histidine. c. The cells can grow on minimal medium + valine. d. The cells can grow on minimal medium.
c
Which of the following statements about a protein domain is FALSE? a. Within a single protein, different domains may serve different functions, such as ligand-binding or catalysis. b. Domains may have resulted from exons of different genes, which were reshuffled during evolution. c. A domain consists of a single type of secondary structure. d. Each protein contains at least one domain but may contain several domains
c
Which of the following statements best describes the function of aminoacyl tRNA synthetase? a. It helps tRNA synthesize proteins. b. It synthesizes tRNA molecules. c. It attaches a specific amino acid to a tRNA molecule. d. It provides the energy required to attach a specific amino acid to a tRNA molecule.
c
Which of these D N A sequences is palindromic when double-stranded? a. 5'-A T G G T A-3' b. 5'-A T G A T G-3' c. 5'-A T G C A T-3' d. 5'-T A T C G C-3' e. 5'-C C C C C C-3'
c
Which region of a tRNA molecule binds to amino acids? a. Codon loop b. Variable loop c. 3′ end d. Anticodon loop
c
You are interested in knowing whether the addition of estrogen to your cell culture induces expression of m RNA from your gene of interest. Of the following choices, a good way to determine that is using a. Southern blot b. Western blot c. reverse transcriptase PCR (RT-PCR) d. transgenic female animals e. next-generation sequencing
c
ddATP, ddTTP, ddCTP, and ddGTP are labeled with red, green, yellow, and blue fluorescent dyes, respectively. A five-base read from a sequencing reaction produced the following color sequence, read by the computer: red, yellow, yellow, green, green. What is the sequence of the template DNA? a. AAGGT b. TGGAA c. ACCTT d. TTCCA
c
A protein is 300 amino acids long. Which of the following could be the number of total nucleotides in the section of DNA that codes for this protein? (Remember: DNA is double-stranded.) a. 300 b. 3 c. 900 d. 1800 e. 100
d
A scientist is troubleshooting the synthesis of a cDNA library. The scientist performs both a Northern and a Southern blot. The Northern blot demonstrated the presence of RNA while the Southern blot indicated that no cDNA was present in the sample. What is likely to be the cause of the failed synthesis of the cDNA library? a. too many dNTPs b. proper primers c. temperature too cold for annealing d. defective reverse transcriptase
d
All EXCEPT which of the following are differences between eukaryotic and prokaryotic DNA replication? a. the number of replication origins b. the rate of DNA synthesis c. the type and number of polymerases involved in DNA synthesis d. the ability to form a replication fork
d
All of the following are examples of posttranslational modifications, EXCEPT________. a. Polypeptide chains can be cleaved to produce a shorter and functional polypeptide. b. The N-terminal amino acid is often removed or modified. c. Individual amino acid residues are sometimes modified, such as adding a phosphates, acetyl, or methyl groups can be added. d. Polypeptides can be degraded and then reassembled to produce entirely different sequenced polypeptides. e. Prosthetic groups, such as metals or vitamins, can be added.
d
As unwinding of the helix occurs during DNA replication, tension referred to as ________ is created ahead of the replication fork. This tension is relieved by the action of ________. a. processivity; primase b. supercoiling; DNA helicase c. supercoiling; single-stranded binding proteins c. processivity; DNA gyrase d. supercoiling; DNA gyrase
d
Considering the types of side chains on amino acids and their relationship to protein structure, where are the amino acids with hydrophobic side chains most likely to be located? a. Closer to the water environment and in the exterior portion of the molecule. b. Hydrophobic side chains will form a hydrophobic cluster folding the protein in a single globule. c. Hydrophobic side chains will alternate with hydrophilic side chains. The hydrophilic side chains will hide the hydrophobic side chains from the water environment. d. Away from the water environment and in the interior portion of the molecule.
d
Considering transcription initiation, the core promoter in eukaryotes is homologous to what in prokaryotes? a. rho b. Sigma 70 c. core enzyme d. Pribnow Box e. Goldberg-Hogness box
d
During bacterial translation initiation, the m R N A _____. a. binds to the large subunit b. is oriented so that the A U G start codon is in the A site c. only binds f-met t R N A after the entire ribosome has been assembled d. is oriented by its Shine-Delgarno sequence through base-pairing with an r R N A e. requires A T P hydrolysis for binding to the ribosomal subunit
d
Eukaryotic D N A replication is more complex than prokaryotic because all of these except: a. There is more DNA in eukaryotes than in prokaryotes b. The chromosomes are linear c. DNA is complexed with nucleosomes d. There is a single origin of replication
d
Fluorescence in situ hybridization is another way to visualize the presence of a nucleotide sequence. Which of the following is an advantage of FISH over Northern and Southern blots? a. There are no advantages to FISH over Northern and Southern blots. b. Fluorophores are not used in Northern or Southern blots. c. Probes are not needed in FISH. d. Blotting is not used in FISH.
d
If humans had 25 amino acids instead of 20 amino acids then how many aminoacyl tRNA synthetases would humans have? a. 4 b. 75 c. 20 d. 25 e. 3
d
In bacteria, the methionine that initiates the formation of a polypeptide chain differs from subsequently added methionines in that _______. a. incorporation of the initial methionine does not require a tRNA b. the initiating methionine is not an amino acid c. its tRNA anticodon is not complementary to the AUG codon d. a formyl group is attached to the initiating methionine
d
In humans, the phenylalanine hydroxylase gene is 90,000 (90 k b) bases long, yet the m R N A is only 2,400 (2.4 k b). What explains this difference? a. RNA editing b. Removal of exons in the final m R N A c. Loss of stability without a 5′ cap d. Presence of introns in D N A e. Code for poly A tail that is removed in m R N A
d
R N A editing can be the result of insertion/deletion editing. This results in _______________. a. Removal of introns after transcription b. Addition (and subsequent removal) of poly-A tail as part of regulation of expression c. Removal of T's added to m R N A by mistake and replacement with U's d. Changes to the m R N A sequence after transcription e. Switching one base for another
d
The CRISPR-Cas system of gene editing is based on what naturally occurring biological process? a. eukaryotic defense against viral infection b. viral defense against eukaryotic defenses c. viral defense against bacterial defenses d. bacterial defense against viral infection
d
The discontinuous aspect of replication of DNA in vivo is caused by ________. a. polymerase slippage b. topoisomerases cutting the DNA in a random fashion c. trinucleotide repeatssister-chromatid exchanges d. the 5′ to 3′ polarity restriction
d
The results of the Meselson-Stahl experiments relied on all of the following except _______. a. a cesium chloride gradienta b. means of distinguishing among the distribution patterns of newly synthesized and parent molecule DNA possible c. that a heavy isotope of nitrogen could be incorporated into replicating DNA molecules d. the fact that DNA is the genetic material
d
The synthesis of a new DNA strand along the template is performed by ________________. The role of the _________________ is to ensure that the enzyme creating the new DNA strands does not become unattached from the template strand. To prevent knotting of the template DNA as the replication fork moves, _________ makes temporary nicks in the template DNA. The replication fork contains template DNA strands that were recently separated by __________ to become single stranded. To ensure that single strands near the replication fork do not reanneal to each other, _______________ attach to template strands. a. DNA gyrase, DNA helicase, single-stranded binding proteins, DNA polymerase, sliding clamps subunit. b. DNA polymerase, DNA helicase, sliding clamps subunit, DNA gyrase, single-stranded binding proteins. c. DNA helicase, single-stranded binding proteins, DNA gyrase, DNA polymerase, sliding clamps subunit. d. DNA polymerase, sliding clamps subunit, DNA gyrase, DNA helicase, single-stranded binding proteins.
d
There are multiple cloning vector types in modern recombinant DNA technology ranging from plasmids to viral vectors. Which vector type is most useful when cloning an insert of approximately 500kb? a. bacterial plasmid b. human artificial chromosome c. bacterial artificial chromosome d. yeast artificial chromosome e. viral vector
d
Translation in bacterial and eukaryotic cells has many similarities, but there are also several key differences. Which of the following is one of those differences that is seen in eukaryotes? a. Translation and transcription are coupled. b. Eukaryotic ribosomes are smaller with fewer proteins and RNA molecules. c. Eukartyotic mRNA contains a ShineDalgarno sequence that increases the efficiency of translation. d. Eukaryotes use the 5 G-cap and Poly-A-tail on their mRNAs to initiate translation. e. Eukaryotes only require one release factor that recognizes all three stop codons.
d
What does the term "processivity" mean in the context of D N A replication? a. that the D N A polymerase III holoenzyme has completed its self-assembly b. that the D N A polymerase III has completed one round of D N A replication c. that the D N A polymerase III is replicating bidirectionally d. that length of D N A that is replicated by the core enzyme before it detaches from the template e. the ability to move "backward" for proofreading.
d
What is meant by processivity of a DNA-synthesizing enzyme? a. The strength of the association between the enzyme and DNA, and thus the number of new DNA molecules that is synthesized before the enzyme dissociates from the template. b. The strength of the association between the enzyme and its cofactors, and thus the speed of the new DNA strand synthesis. c. The strength of the association between the enzyme and dNTPs, and thus the speed of the new DNA strand synthesis. d. The strength of the association between the enzyme and its substrate, and thus the length of DNA that is synthesized before the enzyme dissociates from the template.
d
What is the function of restriction endonucleases in bacteria? a. They serve no function. b. They allow bacteria to genetically recombine with other bacteria. c. They allow bacteria to engineer new DNA fragments. d. They provide a defense mechanism against infection by viruses.
d
What is the main purpose of a DNA probe? a. extend the growing polynucleotide b. binds to proteins c. cuts DNA targets d. hybridizes to a target sequence
d
What is the most serious drawback to using library screening to study genetics? a. The product of the gene must be known in order to design enzyme probes to locate the gene in the library. b. The promoter of the gene must be known in order to design primers to amplify the gene in the library. c. The sequence of adjacent genes must be known in order to identify all the copies of the gene in the library. d. The sequence of the gene must be known in order to design probes to locate the gene in the library.
d
What is the order of the three main steps in a PCR? a. elongation, annealing primers, denaturation b. denaturation, elongation, annealing primers c. annealing primers, denaturation, elongation d. denaturation, annealing primers, elongation
d
Which of the following bacterial RNA polymerase subunits is found in the holoenzyme, but not the core enzyme? a. β (beta prime) b. α (alpha) c. ω (omega) d. σ (sigma) e. β (beta)
d
Which of the following best describes a cloning vector? a. A DNA molecule that accepts DNA fragments and degrades them in a host. b. The direction in which DNA is cloned. c. The fragment of DNA encoding a gene of interest. d. A DNA molecule that accepts DNA fragments and replicates the fragment in a host
d
Which of the following best describes the first step in the formation of the translation initiation complex? a. The large ribosomal subunit binds to an mRNA sequence near the 5' end of the transcript b. The large ribosomal subunit binds to the small ribosomal subunit. c. The small ribosomal subunit binds to an mRNA sequence near the 3' end of the transcript. d. The small ribosomal subunit binds to an mRNA sequence near the 5' end of the transcript
d
Which of the following complexes bind to an open A-site in the process of translational elongation? a.charged tRNA b. charged tRNA+GTP c. charged tRNA+elongation factor d. charged tRNA+elongation factor+GTP
d
Which of the following is true regarding the tRNA structure? a. The anticodon is found at the 3 end of the tRNA molecule. b. The nucleotides found in a tRNA molecule can only be adenine, uracil, guanine, and cytosine. c. The tRNA binds to an mRNA's codon at the variable loop. d. A tRNA molecule that has an amino acid attached to it is called a charged tRNA. e. An amino acid binds to the 5 end of the tRNA molecule.
d
Which of the following would result from a third round of replication using the methods of Meselson and Stahl? a. One heavy band, one light band, and one intermediate band b. One heavy band c. One light band d. One light band and one intermediate band
d
Which three steps constitute a PCR cycle? a. Inactivation, activation, and transfer b. Naturation, annealing, and photolysing c. Transfection, transformation, and transduction d. Denaturation, annealing, and extension
d
Which type of mutation helped lead to the understanding that the genetic code is based on triplets? a. Missense mutation within the promoter b. Base substitution (substitution of one base for another) c. Nonsense d. Frameshift
d
In a particular bacterial mutant, a specific gene is not producing a mRNA or the corresponding protein. Researchers sequence the gene and determine that there are no mutations in the coding portion of the gene. Choose the structures that could be mutated to explain these observations. (select all that apply) a. splice sites b. poly-A tail c. termination sequences d. Pribnow box (TATAAT) e. −35 sequence (TTGACA)
d & e
A researcher is studying the synthesis of a specific amino acid found in Neurospora. She knows that the pathway begins with a precursor that is converted into the amino acid with two known intermediates (Substance Blue and Substance Green). She accurately predicts that this amino acid synthesis pathway is catalyzed by three enzymes, (I, II, and III). She subsequently identifies three mutants that she calls Mutant I, Mutant II, and Mutant III. With the information about the mutants below place the enzymes in the order that the enzymes act in this pathway. (Note: the numbers I, II, and III don't necessarily indicate the order in which the enzymes appear.) Mutant I (only Enzyme I is mutated) is unable to synthesize the amino acid even if she provided the mutant with both Substance Blue and Substance Green.Mutant II (only Enzyme II is mutated) is able to synthesize the amino acid if she provided the mutant with Substance Blue or Substance Green.Mutant III (only Enzyme III is mutated) is able to make the amino acid if she provided the mutant with Substance Green, but not if she provided the mutant with only Substance Blue. a. I , II, III B. II, I , III c. III, II, I d. III, I , II e. II, III, I
e
Archibald Garrod's work suggested that _____. a. D N A is the genetic material b. each gene codes for a unique ribosome c. each gene is associated with the production of a single polypeptide d. biologically active D N A is in a double-helical structure e. inherited factors control metabolic activities
e
DNA ligase ________. a. adds bases into a growing DNA molecule b. removes bases from a DNA molecule c. reconnects the bases together between the DNA strands d. cuts the DNA to produce sticky or blunt ends e. reconnects the phosphodiester linkage between bases on the same strand of DNA
e
If DNA replication were fully conservative, how many intact parental double helices would have been detected in Meselson and Stahl's experiment after three rounds of replication? a. 3 b. 0 c. 7 d. 8 e. 1
e
If one compares the base sequences of related genes from different species, one is likely to find that corresponding ________ are usually conserved, but the sequences of ________ are much less well conserved. a. introns; chaperons b. introns; exons c. introns; proteins d. chaperons; exons e. exons; introns
e
In the polymerase chain reaction, the purpose of the step in which the temperature is between 70°Celsius and 75°Celsius is _____. a. to denature the D N A b. to denature the polymerase c. to allow the primers to anneal d. to allow the primers to release from the template e. to allow DNA polymerase to synthesize D N A
e
Restriction mapping is used to characterize cloned DNA. What does a restriction map tell the researcher about the cloned DNA? a. The distances between restriction sites for the specific restriction enzyme. b. The number of restriction sites for the specific restriction enzyme. c. The size of the genome the cloned DNA was isolated from. d. The restricted conditions under which the organism can grow. e. The number of sites and distance between them for the specific restriction enzyme
e
Structures located at the ends of eukaryotic chromosomes are called ________. a. recessive mutations b. centromeres c. telomeres d. permissive mutations e. telomeres
e
Telomerase _____. a. contains its own R N A template b. is a reverse transcriptase c. extends one strand of the telomere d. is responsible for helping to maintain chromosome size e. all of the above
e
The generation of a knock-out organism generally requires all the following EXCEPT ________. a. a selectable marker b. a targeting vector c. knowledge of the target sequence d. embryonic stem cells e. knowledge of the sequence product
e
The poly(A) tail of m R N A _____. a. is added to the 3′ end of most eukaryotic m R N As b. is found on most mature eukaryotic m R N As c. helps terminate transcription d. helps prevent degradation of eukaryotic m R N As e. all of the above are correct.
e
The primary structure of a protein is determined by ________. a. covalent bonds formed between fibroin residues b. hydrogen bonds formed between the components of the peptide linkage c. pleated sheets d. a series of helical domains e. the sequence of amino acids
e
The β chain of adult hemoglobin is composed of 146 amino acids of a known sequence. In comparing the normal β chain with the β chain in sickle cell hemoglobin, what alteration is one likely to find? a. frameshift substitutions b. glutamic acid replacing valine in the first position c. extensive amino acid substitutions d. trinucleotide repeats e. valine instead of glutamic acid in the sixth position
e
What is the purpose of the dideoxynucleotides in computer-automated D N A sequencing? a. To cause defined chain termination b. To label the synthesized D N A c. To help transfer the D N A to the membrane d. To aid in electrophoresis e. Both a and b
e
What protein is functioning at the point marked with the large arrow? a. DNA ligase b. helicase c. gyrase d. DNA polymerase I e. DNA polymerase III
e
When choosing a restriction enzyme for use in recombinant DNA technologies, it is often preferred that the enzyme generate cohesive, or "sticky," ends. Why is this preferred? a. The sticky ends make the DNA bind tighter to any cut DNA. b. The sticky ends do not have hydrogen bonds to help in re-annealing the cut DNA. c. The sticky ends prevent the DNA from re-annealing to any DNA. d. The sticky ends stick to the purification medium making the fragments easier to purify. e. The sticky ends have hydrogen bonds that help re-anneal the cut DNA.
e
