Biochemistry Review A
27.(1 point) In oxygenated myoglobin, the oxygen molecule does which ONE of the following? A.becomes the sixth coordinating link to the heme iron. B.causes the reversible oxidation of Fe2+ to Fe3+. C.forces a change in conformation of one alpha-helix to a beta-strand. D.is coordinated to the imidazole side-chain of the distal histidine. E.replaces a histidine side chain in the iron coordination system.
A. Becomes the sixth coordinating link to the heme iron
33.(1 point) Why does sickle cell anemia NOT cause problems for fetuses that carry the genetic defect (hemoglobin SS)? A.The synthesis of hemoglobin SS does not begin until around the time of birth B.The imbalance of globin chain synthesis is less during fetal life C.Maternal oxygen affinity differs from that of the fetus D.Stillborn infants with sickle cell anemia are common
A. The synthesis of hemoglobin SS does not begin until around the time of birth
24.(1 point) How does fetal hemoglobin (Hb F) differ from normal adult hemoglobin (HbA)? Choose the ONE best answer. A.A histidine residue in Hb A is replaced with a neutral amino acid in Hb F. B.An alpha chain lysine residue in Hb A is replaced with a neutral amino acid in HbF. C.Hb F has a greater tendency to associate in the deoxygenated state. D.Hb F has a greater affinity for CO. E.Hb F exhibits enhanced oxygen unloading versus Hb A at the same pO2
A. A Histidine residue in Hb a is replaced with a neutral amino acid in Hb F
52.(1 point) Mismatch repair is characterized by each of the following observations EXCEPT for which ONE? A.Recognition of a mismatch site by a specialized "mut" protein B.The presence of 5-methyl cytidine in the sequence GATC C.The existence of a mismatch within 1 kb of a GATC sequence D.Endonuclease cleavage at the 5' side of GATC E.A high incidence of cancer when one of the "mut" proteins is lacking
B. The presence of 5-methyl cytidine in the sequence GATC
32.(1 point) Which ONE of the following statements is TRUE concerning sickle cell anemia (hemoglobin SS)? A.It's inheritance follows an autosomal dominant pattern B.It's patients have an elevated level of hemoglobin A2 C.Premature red cell breakdown leads to anemia D.Heart attacks are common among children with the disease
C. Premature red cell breakdown loads to anemia
25.(1 point) The O2 binding affinity of hemoglobin decreases when there is a decrease in which ONE of the following? A.ionic strength B.2,3 -bisphosphoglycerate concentration C.carbon dioxide concentration D.pH E.vitamin C
D. pH
59.Uracil is not found in DNA because it would base pair with G
FALSE
10.(1 point) Which ONE of the following enzymes is required for formation of cross-linksin collagen? A.pro-collagen peptidase B.protein disulfide isomerase C.elastase D.lysyl oxidase E.protein desmosine oxidase
D. Lysyl oxidase
50.(1 point) Telomere shortening might be expected to occur in all of the following situations EXCEPT for which ONE? A.A down-regulation of telomerase activity B.Elimination of the telomerase RNA-encoding gene C.Highly differentiated mammalian cells D.Very old bacterial cells E.Enhanced 3' to 5' exonuclease activity in the cell
D. Very old bacterial cells OR E. Enhanced 3' to 5' exonuclease activity in the cell
20.(1 point) Which ONE of the following ionic species of glutamate is predominant at pH10.5?
E
71.(1 point) Lac repressor displays each of the following characteristics except for which ONE? A.Binds to a specific dyad symmetric DNA sequence B.Typically functions in a tetrameric complex at the lac operon C.Blocks passage of RNA polymerase D.Requires allolactose to inhibit its ability to bind to DNA E.Regains its ability to bind to DNA in the absence of glucose
E. Regains ability to bind to DNA in the abscence of glucose
14.(1 point) Which ONE of the following statements is TRUE for proline and hydroxyproline in collagen? A.Hydroxylation occurs on the collagen protein after synthesis on the ribosome B.Proline in native collagen results from dehydroxylation of hydroxyproline C.Collagen is not synthesized on ribosomes permitting direct insertion ofhydroxyproline D.Hydroxylation of proline occurs on the prolyl-tRNA E.There are separate codons for hydroxyproline and proline
A. Hydroxilation occurs on the collagen protein after synthesis on the ribosome
1.(1 point) Which ONE of the following is most responsible for the maintenance of protein secondary structure? A.Hydrophobic interactions B.van der Waals forces C.Hydrogen bonds D.Disulfide cross-links E.Salt bridges
C. Hydrogen Bonds are responsible for stabilizing the secondary structure.
19.(1 point) Given the following 5 amino acids, which ONE of them is the most hydrophilic at pH 7.0? A.serine B.asparagine C.methionine D.arginine E.glycine
D. Arginine
64.(1 point) In order for prokaryotic transcription to be initiated all of the following have to occur except for which ONE? A.The promoter needs to be recognized by holoenzyme B.DNA downstream of the promoter has to be "melted" C.Sigma factor has to accompany the polymerase to the promoter D.The DNA strand that acts as a template is the one that reads 5' to 3' E.Two molecules of rNTP are condensed to form the first phosphodiester bond
D. The DNA strand that acts as a template is the one that reads 5' to 3'
63.(1 point) Several different proteins can be synthesized from a typical prokaryotic mRNA because of which ONE of the following? A.Any of the 3 reading frames can be used B.There is redundancy in the choice of codon/tRNA interactions C.The gene contains several operator sequences from which to initiate translation D.Alternative splicing events are commonly found E.Many mRNAs are organized in a series of consecutive translational cistrons
E. Many mRNAs are organized in a series of consecutive translational cistrons
13.(1 point) At their isoelectric point proteins exhibit which ONE of the following? A.no ionized groups. B.no positively charged groups. C.no negatively charged groups. D.all of their acidic groups protonated. E.no tendency to migrate in an electric field.
E. No tendency to migrate in an electric field
60.G-C base pairs require less energy to disrupt than A-T base pairs
FALSE
61.Retroviruses are the only known source of dogma-violating reverse transcriptases
FALSE
75.Enhancers can only work from positions upstream of genes
FALSE
78.The concentration of mRNA in the cell is necessarily proportional to its rate of transcription
FALSE
82.Eukaryotes and prokaryotes use a universal genetic code
JOKER _:_
80.Combinatorial regulation of gene expression allows many unique regulatory patterns to evolve from a relatively small number of proteins
TRUE
21.(1 point) Which sequence of atoms can be found in the backbone of polypeptides ? Choose the ONE best answer. A.C-C-N-C B.N-C-C-C C.C-O-C-N D.C-N-N-C E.C-C-C-N
A. C-C-N-C
55.(1 point) The key mechanistic failure in Xeroderma Pigmentosum patients involves which ONE of the following? A.Mutation in the photolyase gene B.Inability to excise a section of UV damaged DNA C.Mutation on one of the mismatch repair components D.Inability to synthesize DNA across the damaged region E.Loss of proofreading capacity
B. Inability to excise a section of UV damaged DNA
6.(1 point) Which ONE of the following groups of amino acids would be characterized as entirely hydrophobic? A.His, Gly, Ala B.Phe, Ile, Val C.Trp, Glu, Val D.Asn, Glu, ArgE.Asp, Ser, Phe E.Asp, Ser, Phe
B. Phe, Ile, Val
62.(1 point) Transcription in prokaryotes requires all of the following components except for which ONE? A.DNA B.tRNA C.Mg2+ ions D.rNTP's E.RNA polymerase
B. tRNA
7.(1 point) Under which ONE of the following conditions would hemoglobin have the highest affinity for oxygen? A.High bisphosphoglycerate and high pH B.High bisphosphoglycerate and low pH C.Low bisphosphoglycerate and high pH D.Low bisphosphoglycerate and low pH E.Low bisphosphoglycerate and low pH and high CO
C. Low bisphosphoglycerate and high PH
29.(1 point) The primary structure of the collagen alpha-chain is best represented by which ONE of the following? X, Y, and Z represent any amino acid and n=250-400. A.(X-Gly)n B.(Pro-Y-Z)n C.(Lys-Pro-Z)n D.(X-Y-Gly)n E.(Gly-X-Y-Pro)n
D. (X-Y-Gly)n
16.(1 point) At physiological pH, lysine (pK amino group = 9.0; pK carboxylate group =2.2; pK of ionizing side-chain = 10.5) would exist mainly as a species with a net charge of which ONE of the following? A.-2 B.-1 C.0 D.+1 E.+2
D. +1
70.(2 points) tRNA s have several unique features which distinguish them from other types of RNA. From what you have learned in this course, which of the following features are NOT UNIQUE to tRNA? This question may have more than one correct answer; be sure to indicate all correct answers on the answer sheet. A.Ability to form a 3D structure by virtue of intramolecular base pairing B.Modification of the 3' end by non-templated bases C.Presence of inosine residues D.Presence of a methylated G base (or bases) E.Presence of thymine base(s) F.Existence of covalent links to amino acids
A. Ability to form a 3D structure by virtue of intramolecular base pairing B. Modification of the 3' end by non-templated bases D. Presence of a methylated G base (or bases)
26.(1 point) Which ONE of the following is an important difference between hemoglobin(Hb) and myoglobin (Mb)? A.Hb is a heterotetramer containing 2 alpha and 2 beta chains B.Hb binds oxygen more tightly than Mb C.Each chain in Hb contains a heme prosthetic group D.Hb does not bind CO E.The polypeptide chains of Hb are folded mostly into α-helices
A. Hb is a heterotetramer containing 2 alpha and 2 beta chains
9.(1 point) Collagen contains large amounts of which ONE of the following? A.Inter-chain hydrogen bonds B.Intra-chain hydrogen bonds C.ß-sheet D.α-helix E.310 -helix
A. Inter-chain hydrogen bonds
23.(1 point) Which ONE of the following amino acid substitutions most likely causes a change in a protein's tertiary structure? A.Isoleucine to arginine B.Arginine to lysine C.Valine to leucine D.Threonine to serine E.Asparagine to glutamine
A. Isoleucine to arginine
34.(2 points) Nucleic acids are composed of which of the following component parts? This question may have more than one correct answer; indicate all correct answers on the answer sheet. A.Nitrogen-containing heterocyclic bases B.Diphosphate linkages C.Sugars with 6 carbon atoms comprising the ring structure D.5' to 3' phosphodiester linkages E.Deoxyglucose sugars F.2' hydroxyl or 2' deoxy substituents G.Peptide linkage between sugar and base
A. Nitrogen-containing heterocyclic bases D. 5' to 3' phosphodiester linkages F. 2' hydroxyl or 2' deoxy substituentes
28.(2 points) Ionic bonds between positively and negatively charged amino acid side chains, sometimes called salt bridges, often stabilize protein tertiary structures. Given the salt bridge: Over what range of pH will this salt bridge be stable? (Assume that the side chains must be at least 50% charged in order for the salt bridge to be stable and the pK for -NH3 is~10.5 and the pK for -COO- is ~4.0). Choose the ONE best answer. A.between pH 3.0 and 9.5 B.between pH 4.0 and 10.5 C.between pH 5.0 and 11.5 D.between pH 4.0 and 11.5 E.between pH 3.0 and 10.5
B. Between PH 4.0 and 10.5
48.(2 points) Which of the following processes would NOT increase the chances of causing mutations in DNA? This question may have more than one correct answer; be sure to indicate all correct answers on the answer sheet. A.Exposure to UV light B.Incorrect charging of tRNA C.Loss of 3' to 5' exonuclease activity in DNA polymerase D.Translational frameshifting by ribosomes E.Deamination of cytosine bases F.Eating large quantities of wild mushrooms
B. Incorrect charging of tRNA D. Loss of 3' to 5' exonuclease activity in DNA polymerase F. Eating large quantities of wild mushrooms
12.(1 point) Hydroxylation of prolyl residues of procollagen chains by prolyl hydroxylaserequires all of the following EXCEPT for which ONE? A.prolyl residue B.ascorbate C.CO2 D.O2 E.α-ketoglutarate
C. CO2
18.(1 point) Given the following 5 amino acids, which ONE has the bulkiest side chain? A.alanine B.valine C.tyrosine D.histidine E.tryptophan
E. Tryptophan
79.Cellular aging may well be related to the lack of telomerase in the cells
TRUE
30.(1 point) The genetic cause of most cases of alpha thalassemia is which ONE of the following? A.A point mutation of the alpha globin gene B.Mutations affecting the transcriptional regulation of the beta globin gene C.Mutations causing structurally abnormal hemoglobin D.Deletion of one or more alpha globin genes
D. Deletion of one or more alpha globin genes
57. Chemically damaged bases are usually removed and repaired by nucleotide excisionrepair rather than base excision repair
JOKER HAHAHAHAHA
49.(1 point) The Ames test attempts to identify potential mutagens in which ONE of the following ways? A.By converting Salmonella into E. coli B.By selecting for a "back mutation" to convert an inactive gene to an active one C.By using chemically exposed bacteria to infect human cells D.By killing Salmonella bacteriaE.By creating mutations in the histidine codon
B. By selecting for a "back mutation" to convert in inactive gene to an active one
45.(1 point) Okazaki fragments show all of the following characteristics except for which ONE? A.Are mixed DNA/RNA polymers B.Are typically 1000 nucleotides long in prokaryotes C.Are joined together by DNA primase D.Are formed as part of the lagging strand E.Allow a replisome to move in one direction on double stranded DNA
C. Are joined together by DNA primase
8.(1 point) Choose the SINGLE best answer concerning the amino acid cysteine. A.It is required for the formation of tertiary structure in proteins. B.It can be present within the active site of enzymes and function as a nucleophile. C.It forms disulfide bonds in secreted proteins. D.The side-chain thiol has a pK of 6.5. E.Both A and C F.Both B and C
F. Both B and C B.It can be present within the active site of enzymes and function as a nucleophile. C.It forms disulfide bonds in secreted proteins.
81.Mg2+ is needed for replication and transcription but not for translation
FALSE
76.Where proteins form multimeric complexes, one non-functional subunit can have adominant negative effect on the whole complex
TRUE
77.Splicing is one way to increase the diversity of the protein population in an organism starting with a fixed number of genes
TRUE
38.(1 point) Resistance of HIV to nucleoside analogs commonly arises because of which ONE of the following? A.Human cells become impermeable to their uptake B.The virus produces a specific enzyme to degrade the analogs C.Error-prone replication of the viral genome leads to a reverse transcriptase with altered properties D.Reverse transcriptase is no longer needed by resistant viruses E.Viral components inhibit phosphorylation of the nucleoside
C. Error-prone replication of the viral genome leads to a reverse transcriptase with altered properties
42.(1 point) All of the following components except for which ONE are necessary for replicating a prokaryotic chromosome? A.DNA polymerase III B.DNA primase C.RNA polymerase I D.DNA ligase E.Ribonucloside triphosphates
C. RNA polymerase I
46.(1 point) Bidirectional replication is a phenomenon which is best described by which ONE of the following? A.Allows bacteria to grow in two directions at once B.Requires at least two replication origins C.Requires no more than two replisomes D.Cannot occur on linear chromosomes E.Is purely theoretical since it cannot be visualized
C. Requires no more than two replisomes
22.(1 point) In a multisubunit protein such as hemoglobin, the individual polypeptide chains are usually bound to one another by all of the following EXCEPT for which ONE? A.hydrogen bonds B.electrostatic interactions C.hydrophobic interactions D.peptide bonds
D. Peptide bonds
54.(1 point) The enzyme telomerase synthesizes DNA strands at the end of chromosomes through which ONE of the following mechanisms? A.By converting DNA polymerase into a continuously cycling mode B.By adding each of the 4 nucleotides in turn to produce a repetitive sequence C.By extending the leading strand via instructions from its own internal template D.By violating the usual rule and synthesizing DNA 3' to 5' E.By adding long poly-A tails to the leading strand
C. By extending the leading strand via instructions from its own internal template
51.(1 point) When cytosine deamination occurs in DNA all of the following activities are needed to repair the lesion except for which ONE? A.DNA ligase B.AP endonuclease C.Uracil DNA glycosylase D.DNA primase E.DNA polymerase
D. DNA primase
72.(1 point) Complementation in trans signifies which ONE of the following molecular scenarios? A.DNA in one strand is complementary to DNA in the other strand B.It is a technical term for referring to coupled transcription and translation C.The ability of DNA sequences on different chromosomes to hybridize to oneanother D.The protein product of a gene on one piece of DNA is able to compensate for amutant, non-functional version of the protein encoded on another E.The transport of proteins from the cytoplasm to the nucleus, or vice-versa
D. The protein product of a gene on one piece of DNA is able to compensate for amutant, non-functional version of the protein encoded on another
44.(2 points) Which of the following enzymatic activities are NOT contained within DNA polymerase I? This question may have more than one correct answer; be sure to indicate all correct answers on the answer sheet. A.Making internucleotide linkages in the 5' to 3' direction B.Destroying internucleotide linkages in the 5' to 3' direction C.Having an exonuclease activity specific for RNA but not DNA D.Making internucleotide linkages in the 3' to 5' direction E.Destroying internucleotide linkages in the 3' to 5' direction
C. Having an exonuclease activity specific for RNA but not DNA. D. Making internucleotide linkages in the 3' to 5' direction
11.(2 points) Which ONE of the following is directly responsible for initiation of triple helix formation during procollagen biosynthesis? A.deamination of lysine residues to form an aldehyde group and formation of crosslinks. B.intra-peptide disulfide bond formation in the N- terminal pro-peptide of procollagen. C.hydroxylation of lysine residues in the procollagen protein. D.inter-peptide disulfide bond formation between C- terminal pro-peptides of procollagen. E.removal of cross-linked C- terminal pro-peptides in mature collagen.
D. Inter-peptide disulfide bond formation between C-terminal pro-peptides of procollagen
74.(1 point) Frequently seen features among DNA binding proteins include all of thefollowing EXCEPT for which ONE? A.The existence of a specific " helix that lies across the major groove of DNA B.The ability to form dimers between identical or non-identical partners C.The ability to form multiple hydrogen bonds between amino acid side chains and the edges of base pairs in the double-strand D.The ability to interact with small molecule effectors to alter DNA binding ability E.The ability to recognize RNA molecules with the same sequence
E. Ability to recognize RNA molecules with the same sequence
53.(1 point) 5-methyl cytidine is present in high quantities in mammalian DNA, so it is likely to be a hot-spot for mutation because of which ONE of the following? A.It is unable to base-pair with G, hence creating a distortion in DNA B.It is hydrolyzed to give 5-methyl uracil, which is removed by uracil DNA glycosylase to leave an unrepaired gap in DNA C.It is deaminated to thymine, which results in a G:T mismatch D.It should not be there in the first place E.It causes DNA polymerase to utilize incorrect bases when encountering it on the template strand
C. It is deaminated to Thymine, which results in a G:T mismatch
5.(2 points) Conversion of the T form of hemoglobin to the R form is INCORRECTLY described by which ONE of the following statements? A.Subunit interface displacement occurs resulting in a smaller central cavity. B.BPG binding is reduced by a factor of 100 fold. C.The iron atom moves into the plane of the protoporphyrin IX ring. D.Movement of the proximal histidine pulls several other residues in the F helixalong with it. E.Tyrosine 145 forms a hydrogen bond with aspartate 94 in the β-chain
E. Tyrosine 145 forms a hydrogen bond with aspartate 94 in the β-chain
15.(1 point) Which ONE of the following statements is TRUE for collagen? A.The fundamental collagen polypeptide is an alpha-chain that forms alpha-helices. B.Collagen fibrils are formed by the self-assembly of procollagen molecules. C.The carbohydrate residues are bound to hydroxyproline. D.Glycine makes up nearly one third of the amino acid residues. E.Arrangement of collagen fibrils is determined by the presence of alanine.
D. Glycine makes up nearly one third of the amino acid residue
3.(2 points) Which ONE of the following statements concerning 2,3 bisphosphoglycerate(BPG) is INCORRECT? A.BPG binding increases the oxygen affinity of hemoglobin. B.The stoichiometry of BPG is one molecule per hemoglobin tetramer. C.BPG stabilizes the T form of hemoglobin through ionic bonds. D.In the complete absence of BPG, hemoglobin and myoglobin are observed to haveidentical oxygen binding properties. E.The binding of BPG is weaker to fetal hemoglobin than to the adult form.
A. BPG binding increases the oxygen affinity of hemoglobin tetramer.
73.(1 point) Finely tuned gene transcription levels in cells are typically controlled by which ONE of the following? A.Unique combinations of positively or negatively acting transcription factors B.A combination of messenger half-life and transport of mRNAs C.Presence of either F factor or TFIID D.The presence or absence of mutations in promoters or other regulatory regions E.The relative concentration of glucose versus lactose in the cells
A. Unique combinations of positively or negatively acting transcription factor
67.(2 points) Most eukaryotic genes produce mRNAs that are processed. Which of thefollowing are correct statements regarding this process? This question may have morethan one correct answer; indicate all correct answers on the answer sheet. A.All processing occurs before the mRNA is fully synthesized B.Capping of the 5' end occurs as soon as the 5' end emerges from the polymerase C.The capping machinery uses methylated GTP to create the cap D.Polyadenylation occurs after the repeated sequence AUUUA is produced at the 3'end E.All processing is completed before transport of the mature mRNA to the cytoplasm F.Alternative splicing only occurs when mutations in or around the intron sequences have been sustained
B. Capping og the 5' end occurs as soon as the 5' end emerges from the polymerase E. All processing is completed before transport of the mature mRNA to the Cytoplasm
(1 point) Each of the following features are characteristics of introns except for which ONE? A.100% conservation of a dinucleotide sequence at both their 5' and 3' ends B.Contain a poly purine sequence directly adjacent to their 3' end C.Always form a lariat through an A residue about 30 nt from the 5' end D.Bind to protein/RNA complexes called snRNP's to facilitate splicing E.Are not present in prokaryotes
B. Contain a poly purine sequence directly adjacent to their 3' end or C. Always form a lariat through an A residue about 30 nt from the 5' end
2.(1 point) Which ONE of the following statements concerning the properties of heme is CORRECT? AThe heme in sickle cell hemoglobin is unable to bind O2. B.Fe has six coordination positions, four of which are occupied by the nitrogenatoms of the porphyrin ring. C.In deoxyhemoglobin, the sixth coordination position of heme is occupied bywater. D.The fifth coordination position of the Fe+2 is occupied by the distal histidineresidue. E.The heme iron is oxidized as it binds O2
B. Fe has six coordination positions, four of which are occupied by the nitrogenatoms of the porphyrin ring
17.(1 point) When fatty acids are added to water, they aggregate to form micelles. Which ONE of the following is the most important driving force for aggregation? A.Hydrogen bonding between the adjacent carboxy groups. B.Reduction of the hydrocarbon surface area exposed to water. C.Van der Waals interactions between carboxyl groups and water. D.Electrostatic interactions between the carboxyl groups and water. E.Hydrogen bond formation between fatty acids in the micelle.
B. Reduction of the hydrocarbon surface area exposed to water
4.(2 points) Concerning sickle cell anemia and the structure of hemoglobin S, which ONEof the following statements is INCORRECT? A.The molecular consequence of sickle cell anemia results from the mutation ofglutamate 6 to valine in the β-chain of hemoglobin. B.The complementary hydrophobic pocket at the EF corner of the β-chain is inaccessible in the T form of hemoglobin S. C.Sickle cell formation is favored by low oxygen tension in the tissues. D.The solubility of deoxy-hemoglobin S is greatly reduced compared to theoxygenated form. E.Sickle cell anemia does not result from oxidation of the heme iron to the ferricform.
B. The complementary hydrophobic pocket at the EF corner of the β-chain is inacessible in the T form of hemoglobin S.
40.(1 point) Repeating dinucleotide sequences are very common in eukaryotic genomes, e.g. .......ACACACACACACACACACACAC........ Based on what you know, which ONE of the following statements is likely to be correct? A.When occurring within genes they will give rise to a monotonous run of a single amino acid B.depending on the reading frame they will give rise to repetitive runs of 1, 2 or 3amino acids C.Irrespective of reading frame they will produce a run of the same two alternating amino acids D.Ribosomes will rapidly dissociate from mRNAs containing such sequences E.If located within introns they will precipitate alternative splicing events
C. Irrespective of reading frame they will produce a run of the same two alternating amino acids
(2 points) Promoters are ubiquitous elements for all eukaryotic genes. Which TWO of the following statements regarding eukaryotic promoters are INCORRECT? A.Many, but not all, promoters contain a TATAA consensus at ca. -30 bp B.The TATAA sequence is on the sense strand, thereby defining the other strand as the template for transcription C.Many genes need only a TATAA sequence for efficient transcription D.Upstream regulatory elements within 200 bp of the TATAA sequence bind toTFII initiation factors (such as TFIIA and B) and help to recruit TFIID E.Enhancers are typically not considered part of the promoter, though they canaffect transcription rates F.Many of the factors that bind at a TATAA promoter are themselves complexes ofseveral individual proteins
C. Many genes only a TATAA sequence for efficient transcription D. Upstream regulatory elements within 200 bp of the TATAA sequence bind to TFII initiation factors (Such as TFIIA and B) and help to recruit TFIID
69.(2 points) In comparing protein synthesis in eukaryotes and prokaryotes there are many similarities. Which TWO of the following are clearly different between these two groups of organisms? A.Number of GTP molecules consumed per peptide bond completed during elongation B.Presence of polyribosomes on individual mRNA molecules C.Requirement of a chemically modified form of methionine at initiation D.Requirement for a capped mRNA in order to get efficient translation E.Requirement for two species of methionine-specific RNA F.Large numbers of ancillary proteins in both the small and large ribosomalsubunits
C. Requirement of a chemically modified form of methionine at initiation D. Requirement for a capped mRNA in order to get efficient translation
35.(1 point) A typical purine base may be identified by which TWO of the followingcharacteristics? A.4 carbons and 2 nitrogens in the ring structure B.At least one oxygen atom linked to the ring structure C.5 carbons and 4 nitrogens in the ring structure D.A nitrogen atom in the 9 position E.6 carbons and 3 nitrogens in the ring structure F.A carbon atom in the 1 position
C.5 Carbons and 4 nitrogens in the ring structure D. A nitrogen atom in the 9 position
37.(1 point) The reason there are 64 possible codons is which ONE of the following? A.There are 64 aminoacyl tRNA synthetases B.Each base is able to participate in wobbling C.All possible reading frames can be used in this way D.There are 4 possible bases at each of three codon positions E.The more codons, the faster protein synthesis can be accomplished
D. There are 4 possible bases at each of three codon positions
31.(1 point) Which ONE of the following mutations of the beta globin gene would NOT be expected to produce beta thalassemia? A.A point mutation that results in premature chain termination B.A point mutation that results in abnormal splicing of pre-mRNA C.A point mutation that results in defective assembly of the complex required for transcription D.A point mutation that results in the substitution of valine for glutamic acid at position 6
D. A Point mutation that results in the substitution of valine for glutamic acid at position 6
43.(2 points) Which of the following characteristics of proof-reading are essential to maintain fidelity in DNA replication? This question may have more than one correct answer; be sure to indicate all correct answers on the answer sheet. A.Degrading DNA in the 5' to 3' direction B.Using wobble pairing to increase efficiency C.Using methylation differences to determine parent vs daughter strand D.Always having a free 3'-OH end on the strand being synthesized E.Having both a nuclease and a polymerase activity on the same molecule F.Ensuring the correct amino acid is bound to its cognate tRNA
D. Always having a free 3'-OH end on the strand being synthesized E. Having both, a nuclease and a polymerase activity on the same molecule
47.(1 point) DNA replication requires primers in order to proceed because of which ONE of the following? A.DNA primase cannot work de novo B.DNA polymerases need a template from which to copy DNA C.Replication origins cannot be melted in their absence D.DNA polymerases require free 3' ends in order to both make DNA and check it E.DNA primase only works at replication origins
D. DNA polymerases require free 3' ends in order to both make DNA and check it
39.(2 points) In comparing DNA and RNA which features are UNIQUE to one or the other molecule? This question may have more than one correct answer; indicate all correct answers on the answer sheet. A.Contain phosphodiester linkages B.Are synthesized in the 5' to 3' direction C.Can participate in G-C base pairs D.Usually contain both single-stranded and double-stranded regions E.Are created from nucleoside triphosphates F.Can participate in G-U base pairs G.May undergo post-synthetic modification of bases H.Frequently have a 3' poly A tail I.Are considered informational macromolecules J.Are typically repaired in vivo
D. Usually, contain both single-stranded and double-stranded regions F. Can participate in G-U base pairs H. Frequently have a 3' poly tail J. Are typically repaired in vivo
41.(1 point) The stop codons in mRNA are UAA, UAG and UGA. Considering only the 3rd position of the codon, how many other codons are subject to sustaining a nonsense mutation that would lead to the production of one of these? Choose the ONE best answer. A.1 B.2 C.3 D.4 E.5 F.6
E. 5
65.(2 points) mRNAs in prokaryotes and eukaryotes have differences in all of the following features except for which TWO? A.Structure at the 5' end of the mRNA B.Structure at the 3' end of the mRNA C.Temporary existence of lariat structures D.Require transport to the site of translation E.Are translated 5' to 3' F.Are transcribed in the nucleus G.Require initiation factors to be assembled with ribosomes for translation
E. Are translated 5' to 3' G. Require initiation factors to be assembled with ribosomes for translation
36.(1 point) Typical anti-HIV drugs like AZT are toxic to humans because of which ONE of the following reasons? A.Inhibition of the poly A polymerase enzyme B.Incorporation into mRNA C. Completely inhibits the polymerizing ability of DNA polymerase D. Incorporation into full-length viral DNA and thus enhance mutation frequency E.Incorporation into cellular DNA causing termination of replication
E. Incorporation into cellular DNA causing termination of replication
58.Double stranded regions in RNA occur by parallel base pairing rather than theantiparallel base pairing characteristic of DNA
FALSE
56.Cancer is a common consequence of mutation in DNA repair genes
TRUE