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238 Cards in this Set
- Front
- Back
- 3rd side (hint)
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The osmotic pressure of an aqueous solution depends on... A. The chemical nature of the solute B. The molar concentration of the solute C. The hydrophobic effect of the solute D. All of the above |
B. The molar concentration |
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If the R group of an amino acid is -CH3, then the name of the compound is_____ A. Glycine B. Histidine C. Alanine D. Serine |
C. Alanine |
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Amino acids with non-ionizable side chains are zwitterions when they are ______ A. In any solution B. At physiological pH, pH=7.4 C. In acidic solutions only D. In alkaline solutions only |
B. At physiological pH, pH = 7.4 |
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Histidine has a pKa value of 1.6, 6.0 (R group) and 9.3. At pH 8.0, the net charge on histidine is A. Positive B. Negative C. Neutral D. Insufficient information to tell |
C. Neutral |
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Gel-filtration chromotography separates a mixture of proteins on the basis of_________. A. Charge B. Size C. Affinity for ligands in the column matrix D. Density |
B. Size |
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To what level of structure to alpha-helices belong? A. Primary B. Secondary C. Tertiary D. Quaternary |
B. Secondary |
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Conditions in the tissues which enhance the delivery of oxygen by hemoglobin are the presence of A. Carbon dioxide B. 2,3 BPG C. Protons D. All of the above |
D. All of the above |
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In an enzyme reaction involving one enzyme and one substrate, the rate of reaction depends on ... A. Substrate concentration B. Enzyme concentration C. Both substrate and enzyme concentration D. The enzyme concentration at first and the substrate concentration later on |
C. Both substrate and enzyme concentration |
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Acetic acid has a pKa of 4.8. How many milliliters of .2 M acetic acid and 0.2 M sodium acetate are required to prepare 1 liter of 0.1 M buffer solution having a pH of 4.8 A. 500 ml acetic acid, 500 ml sodium acetate B. 250 mL acetic acid, 250 mL sodium acetate, then 500 mL water C. 250 mL acetic acid, 500 mL sodium acetate, then 250 mL water D. 500 mL acetic acid, 250 mL sodium acetate, 250 mL water |
B. 250 mL acetic acid, 250 mL sodium acetate, 500 mL water |
pH = pKa + log (A/HA) |
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According to the Henderson Hasselbach equation, when the concentration of proton acceptor and proton donor are the same, then... A. The carboxylic acid is totally neutralized B. Only salt forms are present C. pH = pKa D. pKa = log (proton acceptor)/(proton donor) |
C. pH = pKa |
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The Michaelis constant, Km, is equal to the _____ A. Maximum velocity that any given enzyme reaction can achieve B. Substrate concentration which gives the best enzyme assay for an enzyme reaction C. Substrate concentration when the rate is equal to half it's maximal value D. Maximum velocity divided by two |
C. Substrate concentration when the rate is equal to half it's maximal value |
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In the Lineweaver-Burke plot of an enzyme reaction, the Km is given by the ________. A. X-intercept B. Y-intercept C. Negative reciprocal of the X-intercept D. Reciprocal of the y-intercept |
C. Negative reciprocal of the X-intercept |
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The __(blank)_____ pressure is the pressure required to prevent the flow of solvent through a solvent permeable membrane that separates two solutions of different solute concentrations. A. Hydrostatic B. Electromotive C. Osmotic D. Partial |
C. Osmotic |
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What is the concentration of hydroxide ion in an aqueous solution with an H+ concentration of 2×10^-5 M? A. 2 x 10^9 M B. 2x10^-19 M C. 2×10^-19 M D. 5 ×10^-10 M |
D. 5 × 10^-10 |
Kw=10^-14 |
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The pH of a 10^-4 M solution of HCl is... A. 3 B. 3.5 C. 4 D. 4.5 |
C. 4 |
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At the midpoint of a titration curve A. The concentration of a conjugate base is equal to the concentration of a conjugate acid B. The pH = pKa C. The ability of the solution to buffer is best D. All of the above |
D. All of the above |
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For a weak acid with a pKa=6.5 l, the effective buffering range is usually considered to be... A. pH 6 to pH 7 B. pH 6.4 to pH 6.6 C. pH 5.5 to pH 7.5 D. Dependent on the Molarity of the acid |
C. pH 5.5 to 7.5 |
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At neutral pH, the net charge on serine is... A. Positive B. Negative C. Zero D. None of the above |
C. Zero |
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At neutral pH, the net charge of Glutamate is... A. -2 B. -1 C. 0 D. +1 |
B. -1 The carboxyl group is deprotonated |
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Proline is distinct among the 20 commonly found amino acids because... A. It is a ring compound B. It is hydrophilic and ionic C. The nitrogen of the amino group is in a ring D. The carbon of the carboxyl group is in a ring |
C. The nitrogen of the amino group is in a ring |
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Alanine, valine, leucine and Isoleucine are important in 3 dimensional structure because they ... A. Are branched B. Are highly hydrophobic C. Are highly hydrophilic D. Attract water molecules |
B. Are highly hydrophobic |
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The amino acids in polypeptide chains which contain sulfur (S) are... A. Cysteine, cystine, and methionine B. Cystine C. Methionine only D. Cysteine and methionine |
D. Cysteine and methionine |
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At the isoelectric pH of an amino acid which has two pKa values the net charge is... A. 0.5 B. 1 C. 0 D. -1 |
C. 0
Isoelectric point is pH at which the overall charge is 0 |
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The pH inside cells is normally near 7. At pH 7 which statement is true about the charges (ionization state) of the alpha - carboxyl and alpha-amino groups of an amino acid? A. The alpha-carboxyl group is 1- and the alpha-amino group is 1+ B. The alpha-carboxyl group is 1+ and the alpha-amino group is 1- C. The alpha-carboxyl group is 1- and the alpha-amino group is uncharged D. Both groups are uncharged (not ionized) at pH 7 |
A. The alpha-carboxyl group is 1- and the alpha-amino group is 1+ |
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The pKa of a certain weak acid is 4.0. Calculate the ratio of proton acceptor to proton donor at pH 7.0 A. 1000:1 B. 20:1 C. 3:1 D. 1:1 |
A. 1000:1 |
10^(pH-pKa) = (A/HA) |
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The peptide bond is which of the following? A. An amide bond B. An Ester bond C. An ether bond D. An amine bond |
A. An amide bond |
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What is the net charge on the tripeptide GRK at pH 7? A. -1 B. 0 C. +1 D. +2 |
D. +2 (+)NH3- Gly- Arg (+) - lys (+)- COO (-) |
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A mixture of 4 proteins (X, Y, Z, and N) is applied to a Gel-filtration column. Given the information supplied, which will elute 1st? X=35,000 g/mol Y = 26,000 g/mol Z = 146,000 g/mol N = 26,000 g/mol A. Z B. Y and N will elute together C. X D. Can or answer without information about Isoelectric point |
A. Z Separates by size Smaller particles have a longer path because they can get caught up in "maze" of porous stationary phase |
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What is the purpose of SDS in SDS-PAGE? A. To selectively bind target protein B. To maintain buffer pH in gel C. To cause the separation to be on the basis of molecular weight only D. To initiate polymerization of acrylamide to form a gel |
C. To cause a separation to be on the basis of molecular weight only Adds extensive negative charge to proteins and denatures them |
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Which is used as the basis of separation of proteins by affinity chromatography? A. The net charge and pI of the protein at the pH of the column B. The proteins molecular weight C. The proteins density D. The selective binding of the protein to a ligand on the column matrix |
D. The selective binding of the protein to a ligand on the column matrix |
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Structural proteins that typically assemble into large cables or threads to provide mechanical support to cells are classified as ________ proteins. A. Fibrous B. Enzyme C. Globular D. Beta-strand |
A. Fibrous |
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The amino acid that destabilizes alpha-helical structures and is usually found at the ends of alpha-helices is a. Glycine B. Alanine C. Aspargine D. Glutamate |
A. Glycine Alanine is good for helicase as they have small R group |
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Which statement is NOT true about an alpha-helix? A. It is usually right handed B. It is a type of Secondary structure C. It frequently contains proline residues D. It is stabilized by hydrogen bonding |
C. It frequently contains proline residues Prioline destabilizes due to its ring structure |
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Which is true about the side chains of residues in an alpha-helix? A. The extend above or below the pleats B. They extend radially outward from the helix axis C. They point toward the center of the helix D. They hydrogen bond extensively with each other |
B. They extend radially outward from the helix |
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Tertiary structure of proteins describe A. Polypeptide folding B. Bringing amino acids far apart in primary structure close together C. Stabilizing protein structure by noncovalent interaction D. All of the above |
D. All of the above |
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Which of these is most likely to be preserved when a protein is denatured? A. Primary structure B. Secondary structure C. Tertiary structure D. Quaternary structure |
A. Primary structure |
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Which of the following statements is most likely to be true of nonpolar R groups in aqueous solution? A. They are hydrophilic and found buried within proteins B. They are hydrophilic and found on protein surfaces C. They are hydrophobic and found buried within proteins D. They are hydrophobic and found on protein surfaces |
C. They are hydrophobic and found buried within proteins |
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Which demonstrates that the primary structure of a protein determines its tertiary structure? A. How the disulfide bonds hold it in the correct shape B. Proteins can refold even when the amino acid sequence is changed C. Proteins refold when the amino acid sequence is the same as in the native conformation D. Chaotropic agents cannot denature the native conformation |
C. Proteins refold when the amino acid sequence is the same as in the native conformation |
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Cooperative binding by hemoglobin... A. Is induced by hemoglobin B. Is a result of different affinities for oxygen by each subunit protein C. Is induced by oxygenation D. Is a result of interaction with myoglobin |
C. Is induced by oxygenation
After one O2 binds affinity for the next O2 increases |
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Which of the following factors determine an enzyme's specificity? A. The 3 dimesional shape of the active site B. The Michaelis constant C. The type of cofactor required for the enzyme to be active D. The prosthetic group on the enzyme |
A. The 3 dimensional shape of the active site |
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The initial velocity of an enzyme reaction (v0) describes ... A. The concentration of the enzyme at maximal velocity B. The concentration of the substrate at maximal velocity C. The concentration of both at the start of the reaction D. The rate of the reaction when the substrate and the enzyme are first mixed |
D. The rate of the reaction when the substrate and the enzyme are first mixed |
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What is the shape of a typical plot of initial rate vs substrate concentration for an enzyme catalyzed reaction that follows Michaelis-Menton kinetics? A. Sigmoidal B. Parabolic C. sinusoidal D. Hyperbolic |
D. Hyperbolic |
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Calculate the value of the maximum velocity for an enzyme catalyzed reaction that follows Michaelis-Menton kinetics if the initial velocity is 6 mM/s at a substrate concentration of 6 mM. The Km for the system is 2 mM. A. 4.5 mM/s B. 8 mM/s C. 8.75 mM/s D. 12 mM/s |
B. 8 mM/s |
Vo = Vmax [S]/(Km + [S]) |
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An enzyme that catalyzes conversions of L - sugars to D-sugars is called an _______. A. Lyase B. Hydrolase C. Synthetase D. Synthase E. Isomerase |
E. Isomerase |
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It us difficult to determine either Km or Vmax from a graph of velocity vs substrate concentration because... A. Too much substrate is required to determine them B. The graph is Sigmoidal C. An asymptotic value must be determined from the graph D. The points on the graph are often not spread out on the hyperbola |
C. An asymptotic value must be determined from the graph |
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In a certain enzyme - catalyzed reaction the following steps occur: 1. A phosphate group on substrate A is transferred to a side chain of an active site residue of the enzyme 2. The dephosphorylated form of substrate A dissociates from the enzyme 3. Substrate B enters the active site and is phosphorylated with simultaneous regeneration of the enzyme in its original form What kind of mechanism is described? A. Random B. Sequential C. Ordered D. Ping-pong |
D. Ping-pong |
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The difference between uncompetitive and competitive inhibitors is that... A. Uncompetitive inhibitors bind irreversibly B. 1/Vmax is the same for all concentrations of uncompetitive inhibitors C. An uncompetitive inhibitor binds only to ES D. A competitive inhibitor binds only to E |
C. An uncompetitive inhibitor binds only to ES
Uncompetitive - Vmax and Km change Noncompetitive - Vmax changes but Km constant |
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An inhibitor binds to a site other than the active site of the enzyme. Which statement correlates with this observation? A. It must be a competitive inhibitor B. The inhibition must be irreversible C. It could be Noncompetitive or uncompetitive inhibition D. It could be irreversible, competitive, Noncompetitive, or uncompetitive. The data do not relate to the type of inhibition |
C. It could be Noncompetitive or uncompetitive inhibition |
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In the Lineweaver-Burke plot of an enzyme reaction, the Vmax is given by the ________. A. X-intercept B. Y-intercept C. Negative reciprocal of the X-intercept D. Reciprocal of the y-intercept |
D. Reciprocal of the y-intercept Negative reciprocal of the X-intercept is the Km |
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Which of the following is not a method by which enzymes decrease the activation energy for biological reactions? A. Modifying the local charge environment B. Forming transient covalent bonds C. Acting as electron donors or acceptors D. Breaking bonds in the enzyme to irreversibly provide energy |
D. Breaking bonds in the enzyme to irreversibly provide energy |
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What type of inhibition is indicated by the data graphed? A. Competitive B. Uncompetitive C. Noncompetitive D. Irreversible |
C. Noncompetitive Can bind to E or ES |
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Which mode(s) of catalysis is/are classified as chemical effects? 1. Transition state stabilization 2. Acid - base catalysis 3. Covalent catalysis 4. Proximity effect A. 3 only B. 1, 2, & 3 C. 2 and 3 D. All of them |
C. 2 and 3 Acid base catalysis and covalent catalysis |
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Which will be different for a catalyzed reaction versus an uncatalyzed reaction? A. Activation energy B. Ground state energy C. Free energy change D. All of the above |
A. Activation energy |
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Aspartate and lysine are in the active site of an enzyme. They are both known to participate directly in catalysis. The pKa's of the residues are found to be 3.2 and 9.6, relectivrly for aspartate and lysine. The optimum pH for the enzyme is 6.4. Which forms of these 2 residues will predominate when the enzyme is most active? A. Aspartate is protonated; lysine is deprotonated B. Both residues are protonated C. Aspartate is deproronated; lysine is protonated D. Both residues are deprotonated |
C. Aspartate is deproronated; lysine is protonated |
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An update of Fischer's lock and key theory of enzyme specificity views the ______ as the lock and ______ as the key. A. Enzyme; substrate B. Substrate; enzyme C. Enzyme; transition state D. Transition state; enzyme |
C. Enzyme; transition state |
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The role of serine at the active site of serine proteases is to act as a(n) __________ catalyst, while the histidine residue serves as a(n) _______ catalyst. A. Strong; weak B. Weak; strong C. Acid-base; covalent D. Covalent; Acid-base |
D. Covalent; Acid-base |
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Unlike coenzymes that are prosthetic groups, _______ are altered in the course of an enzyme reaction and dissociate from the active site. A. Isozymes B. Cosubstrates C. Metalloenzymes D. Holoenzymes |
C. Cosubstrates |
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Active Holoenzymes are formed from ______ in the presence of _______. A. Cofactors; proteins B. Proteins; cofactors C. Apoenzymes; cofactors D. Apoenzymes; proteins |
C. Apoenzymes; cofactors |
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Which is true about natually occuring monosaccharide? A. The L-isomers predominate B. The D-isomers predominate C. The L and D-isomers occur in equal ratios D. The rtio of L and D-isomer varies widely dpending on the source |
B. The D-isomers predominate |
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Examine the Fischer projection below. How is this carbohydrate classified? A. L enantiomer; aldopentose B. L enantiomer; Ketopentose C. D enantiomer; aldohexose D. D enantiomer; ketopentose |
B. L enantiomer; ketopentose |
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What type of bond links the monomers of a polysaccharide? A. Glucotide bond B. Phosphate ester bond C. Petpide bond D. Glycosidic bond |
D. Glycosidic bond |
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Cellulose is not highly branched because it A. Does not have a polysaccharide backbone B. Does not have alpha(1-6) linkages C. Does not have Beta(1-4) linkages D. Is insoluble in water |
B. Does not have alpha(1-6) linkages |
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Metabolic pathways that involve the degradation of large molecules to smaller ones are classified as _____. A. Anabolic B. Catabolic C. Amphibolic D. Intermediary |
B. Catabolic |
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The glycolytic pathway oxidizes glucose to two molecules of pyruvate and also produces a net of two molecules of ATP. ATP allostericaly inhibits the enzyme, PFK-1, that catalyzes the third step of gllycolysis. This is an example of __________. A. Feed-forward activation B. Feedback inhibition C. Negative cooperativity D. Noncompetitive inhibition |
B. Feedback inhibition |
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A reaction that best serves as a control point for regulation ________. A. Is a near equilibrium reaction B. Has a large postiive Delta G C. Is metabolically irreversible D. Follows Michaelis-Menton Kinetics |
C. Is metabolically irreversible |
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Which substance is a product of glycolysis, a precursor of gluconeogensis and a precursor of the citric acid cycle? A. Glucose B. Pyruvate C. ATP D. Coenzyme A |
B. Pyrvate |
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Substrate level phosphorylation A. Describes the conversion of ADP into ATPwith the addition of inorganic phosphate every place throughout the cell B. Describes the formation of ADP by phosphoryl group transfer from 1,3-bisphosphoglycerate C. Is the formation of ATP by phosphoryl group transfer from a higher energy compound D. Both A and C |
C. Is the formation of ATP by phosphoryl group transfer from a higher energy compound Must be an organic phosphate |
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Which of the following is not regulated in glycolysis? A. Pyrvate kinase B. Phosphoglycerate kinase C. Hexokinase D. PFK-1 |
B. Phosphoglycerate kinase 1,3,10 are regulated (hexokinase, PFK-1, and Pyruvate kinase) |
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The conversion of pyruvate to ethanol also causes the _______. A. Oxidation of NADH B. Production of ADP C. Consumption of O2 D. Generation of an ion gradient across mitochondrial membranes |
A. Oxidation of NADH Fermentation acts to regenerate stores of NAD+ to be used in glycolysis to generate ATP |
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Which is among the possible fates of pyruvate after glycolysis? A. Conversion to lactate B. Further reduction by the citric acid cycle C. Conversion to ethanol D. All of the above |
D. All of the above |
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Below is the Fischer projection of D-Glactose. Which is the proper Haworth projection of Beta-D-galactopyranose? |
I Pyranose = 6 membered ring Beta = anomeric OH up D = far left OH up |
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Below is the structure for a cyclic D-monosaccharide. Which is the anomeric carbon atom? |
2 |
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A monosaccharide that consists of 5 carbon atoms, one of which is in a ketone group, is classified as a(n) ________. A. Aldotetrose B. Aldopentose C. Aldohexose D. Ketopentose |
D. Ketopentose |
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Cellulose is not digestible by hmans because it contains glucose units lined by _______-glycosidic bonds. A. Beta-1,2 B. Alpha-1,4 C. Alpha-1,6 D. Beta-1,4 |
D. Beta-1,4 |
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Amylopctin is a form of starch which has __________. A. Only beta-1,4-bonds between glucose units B. Only alpha-1,4-links bonds glucose units C. Both alpha-1,4-and alpha-1,6-bonds between glucose units D. Hemiacetal links joining glucose units |
C. Both alpha-1,4 and alpha-1,6-bonds between glucose units Alpha-1,6 = branches |
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The disaccharide below contains a(n) _________ - glycosidic linkage. A. Alpha-1,4 B. Beta-1,4 C. Alpha-2,4 D. Beta-2,4 |
B. Beta-1,4 |
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Polysaccharide structure can be varied by differences in... A. Chain length (number of sugars in each polysaccharide) B. The kinds(s) of sugars ineach polysaccharide C. The presence of branching D. All of the above |
D. All of the above |
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The hydrolysis of ATP to ADP has a Delta G*=-30 kJ/mol. If an E. Coli cell the concentrations of ATP, ADP and inorganic phosphate are 7.90 mM, 1.04 mM, and 7.9 mM, respectively, which statement is true about the hydrolysis of ATP in the cell? (Assume temperature of 298 K. R = 8.315 J/mol/K) A. Hydrolysis can proceed spontanously B. The hydrolysis is at euilibrium C. The formation of ATP from ADP is occuring moe rapidly than the hydrolyis D. The hydrolysi is being allosterically controlled |
A. Hydrolysis can proceed spontaneously |
DG = DG*+ RT ln(Q) |
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How many ATP molecules are consumed in the hexose sugar stage of glycolysis for every one molecule of glucose? A. 0; ATP is produced, not consumed, by glycolysis B. 1 C. 2 D.3 |
C. 2 |
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Transfer of a higher-energy phosphoryl group to ADP, resulting in ATP occurs when... A. 1,3-bisphosphoglycerate ->3-phosphoglycerate B. Phosphoenolpyruvate (PEP) -> pyruvate C. 3-phosphoglycerate -> 2-phosphoglycerate D. Both A and B |
D. Both A and B |
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Which of the following enzymatic reactions are control points for glycolysis? A. Glucose 6-phosphate isomerase B. Aldolase C. Both A and B D. Neither A or B |
D. Neither A or B Hexokinase, PFK-1, pyruvate kinase |
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Transfer of the phosphoryl group from PEP to ADP to form ATP is an example of... A. A mutase raction B. Isomerization C. Dehydrogenase D. Substrate-level phosphorylation |
D. Substrate level phosphorylation |
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Seven of the ten reaction in the glycolytic pathway have free energy values close to zero. What does this tell us about those reaction? A. They are near equilibrium reactions B. They are not control points for pathway regulation C. They are reversible reactions D. All of the above |
D. All of the above |
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What chemical species activates th GLUT4 protein to transort glucose into cells? A. Adrenaline B. Insulin C. Protein kinase A D. PFK-2 |
B. Insulin |
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There are four enxymes that can catalyze the first step of glycolysis. They are hexokinase I, II, III and glucokinase (hexokinase IV). Hexokinase I, II, and III have Km values near 0.1 mM. Glucokinase has a Km range of 2-5 mM. If after a heavy meal the blood glucose level rises to 8 mM which statement will be true? A. At this high blood glucose level all four hexokinases are saturated with substrate B. Hexokinases I, II, and III are catalyzing at their maximum rate but glucokinase can still respond to increases in blood glucose levels C. None of the enzymes are saturated. All of them help to increase the rate of glycolysis D. The flux through glucokinase will be extremely low. The only signigicant catalysis is done by hexokinases I, II, and III |
B. Hexokinases I, II, and III are catalyzing at their maximum rate but glucokinase can still respond to increases in blood glucose levels |
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PFK-2 and fructose 2,6-bisphosphatase are two names for the same enzyme. The name PFK-2 is used for the enzyme's catalysis of the phosphorylation of fructose 6-phosphate to fructose 2,6-bisphosphate. The name fructose 2,6-bisphosphatase is used for its catalysis of the reverse reaction. What is unique about this enzyme that makes it logical to use two names? A. It is one of very few enzymes that can catalyze both the forwarrd and reverse reactions B. Th enzyme is a monomer when catalyzing the phosphorylation reaction and a dimer when catalyzing the reverse reaction C. The forard and reverse reactions occur in different compartments within the cell, so a different name is used for each activity D. the enzyme is bifunctional. The forward and reverse reactions are catalyzed by the same enzyme |
D, the enzyme is bifunctional. The forard and reverse reactions are catalyzed by the same enzyme |
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In the liver, _____ has a main use for maintaining blood glucose, but it can also be used to synthesize glycogen, or enter the pentose phosphate pathway to produce ribose 5-phosphate. A. Glucose-1-phosphate B. Glucose-1,6-bisphosphate C. Fructose-6-phosphate D. Glucose-6-phosphate |
D. Glucose-6-phosphate |
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When ATP levels are high, glycolysis is (stimulated, reduced) __________, and when AMP levels are high gluconeogenesis is (stimulated, reduced) __________. A. Stimulated; reduced B. Stimulated; stimulated C. Reduced; reduced D. Reduced; stimulated |
C. Reduced; reduced |
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The interconverstion of which pair of subbstates is used as a regulatory point in gluconeogenesis? A. Lactate and pyruvate B. Dihydroxyacetone phosphate and glyceraldehyde-3-phosphate C. Fructose 1,6-bisphosphate and fructose 6-phosphate D. Phosphonolpyruvate and 2-phosphoglycerate |
C. Fructose 1,6-bisphosphate and fructose 6-phosphate |
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Fructose 2,6-bisphosphate _______ glycolysis whlie it ___________ gluconeogenesis. A. Stimulates; stimulates B. Stimulates; inhibits C.. inhibits; stimulates D. Inhibits; inhibits |
B. Stimulates; inhibits Fructose 2,6-bisphosphate stimulates production of ATP |
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The pentose phosphate pathway has two primary products. They are _____________. A. ATP and NADPH B. Oxaloacetate and acetyl CoA C. Sorbitol and fructose D. Ribose-5-phosphate and NADPH |
D. Ribose-5-phosphate and NADPH |
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Gluconeogeneis shares some, but not all, enzymes with the glycolytic pathway. It would appear to be more efficient if both pathways used all of the same enzymes since the pathways are essentially th reverses of each other. Why don't both pathways use all of the same enzymes? A. The reactions where enzymes differ occur in different parts of the cell for glycolysis verses gluconeogenesis B. Enzymes can catalyze a reaction only in one direction, so naturally the two pathways have some enzymes that differ C. In tissues where gluconeogenesis occurs, the gycolyic enzymes are present at extremely low concentrations D. Three of the reaction steps in gluconeogenesis would have prohibitively large, positive free energies if theey used glycolytic enzymes for their catalysis |
D. Three of the reaction steps in gluconeogenesis would have prohibitively large, positive free energies if they used glycolytic enzymes for their catalysis |
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The activity of glycogen phosphorylatse can be controlled by... A. Phosphorylation B. ATP C. Glucose 6-phosphate D. All of the above |
D. All of the above |
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The enzyme for the key regulatory step in glycogen biosynthesis is... A. Glycogen synthase B. Glycogenin C. Branching enzyme D. Phosphoglucomutase |
A. Glycogen synthase |
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Glucagon is excreted when blood glucose is _______ (high, low), while insulin is secreted when blood glucose is ____ (high, low). A. High; high B. High low C. Low; low D. Low; high |
D. Low; high |
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Phosphorylation can be used to either inactivate or activate enzymes. This is a key element in the regulation of glucose metabolism. Phosphorylation of glycogen phosphorylase _________ it; phosphorylation of glycogen synthase _______ it. A. Activates; activates B. Activates; inactivates C. Inactivates; inactivates D. Inactivates; activates |
B. Activates; inactivates Phosphorylase - breaks down glycogen Synthase - builds glycogen |
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The net effect of the eight steps of the citric acid cycle is to... A. Completely oxidize an acetyl group to a carbon dioxide B. Convert pyruvate to succinate C. Produce NAD+ and Q D. Produce 8 ATPfor every pass through the cycle |
A. Completely oxidize an acetyl group to carbon dioxide 1 ATP 3 NADH 1 FADH2 / QH2 |
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Most of the energy released in the citric acid cycle reactions in conserved in ________. A. GTP B. ATP C. NADH and QH2 D. ADP |
C. NADH and QH2 |
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Which enzyme does not catalyze a reaction that releases carbon dioxide? A. Alpha-ketoglutarate dehydrogenase complex B. Pyruvate dehydrogenase C. Malate dehydrogenase D. Isocitrate dehydrogenase |
C. Malate dehydrogenase |
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Which of the following enzymatic reactions are examples of substrrate level phosphorylation? A. Succinyl Co-A synthetase B. Pyruvate kinase C. Phosphoglycerate kinase D. All of the above |
D. All of the above |
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The succinate dehydrogenase reaction is unusual for a dehydrogenase because it uses _________ as an electron acceptor (oxidizing agent) that is regenerated by ubiquinone. A. ATP B. NADP C. Malonate D. FAD |
D. FAD |
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Each of the follwing catalyzed reactions of the citric acid cycle appears to be regulated except... A. Citrate synthase B. Fumarase C. Isocitrate dehydrogenase D a-ketoglutarate dehydrogenase complex |
B. Fumarase |
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Which of the following allosterically activates mammalian isocitrate dehydrogenase? A. ADP B. NADH C. Calcium D. A and C only |
D. A and C only ADP and Calcium |
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About how many total ATP equivalents are generated by the complete oxidation of one molecule of acetyl CoA? A. 1.5 B. 2.5 C. 3 D. 10 |
D. 10 2.5 per NADH 1.5 per FADH2/QH2 1 ATP (GTP) |
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In the mitochondria NADH and QUH2 are essentially oxidized by ______ since it is the terminal electron acceptor. A. Carbon dioxide B. Hydrogen peroxide C. Ozone D. Oxygen |
D. Oxygen |
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In eukaryotes what is the celllular location of the electron transport chain and ATPsynthase complexes? A. Plasma membrane B. Cytosol C. Innner mitochondrial membrane D. Endoplasmic reticulum |
C. Inner mitochondrial membrane |
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In the respiratory electron transport chain electrons are passed from ________ . A. NADH and QH2 to O2 B. O2 to NAD+ and Q C. O2 to NADH D. ATP to O2 |
A. NADH and HQH2 to O2 |
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Oxidative phosphorylation requires all of the items listed below except... A. ATP synthase in the correct position in the membrane B. Enzyme complexes embedded in a membrane C. The flow of electrons fromNADH and QH2 in the membrane D. A matrix more positively charged than the intermembrane space |
D. A matrix more positively charged than the intermembrane space NO, the intermembrane space needs to have a lot of protons which are positively charged so it is more positively charged |
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The chemiosmotic theory explains... A. The phosphorlyation of ADP B. The electron transport chain C. The diferences between the inner and outer mitochondrial membranes D. The source of energy for formation of mitochondrial ATP |
D. The source of energy for formation of mitochondiral ATP. |
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How many protons are translocated across the membrane by complex I for every pair of electrons that are passed from NADH to QH2? A. 1 B. 2 C. 3 D. 4 |
D. 4 |
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Which complex in the electron transport chain does not contribute to the proton gradient? A. I B. II C. III D. IV |
B. II
Produces QH2 to carry electrons to complex III |
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The terminal electron acceptor for complex III of the electron transport chain is _________. A. Q B. Fe-S C. FAD D. Cytochrome C |
D. Cytochrome C |
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Overall, the emembrane-associated electron transport system pumps __________ protons acros the membrane or every molecule of NADH that is oxidized? A. 2 B. 5 C. 6 D. 10 |
D. 10 4 hydrogens in complex 1 and 3, 2 in 4 4 hydrogens needed to generate 1 ATP |
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An investigator is measuring the activity of various enzymes involved in reactions of metabolism. One of the enzymes has greatly decreased activity compared to the referecnce values. The buffer of the assay contains citrate. Which of the following enzymes will mosy likely be directly affected by the use of citrate? A. Fructose-2,6-bisphosphate B. Isocitrate dehydrogenase C. Phosphofructokinase-1 D. Pyruvate carboxylase |
C. Phosphofructokinase-1 |
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After an overnight fast, which of the folloing processes would be expected to occur at an elevated rate compared with the well fed state? A. Glycolysis B. Glycogen degradation C. Glycogen synthesis D. Glycerol synthesis |
B. Glycogen degradation |
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The reduction half-reaction in the laast step of the electron transport chain is... A. O2 + 4 e- + 4 H+ -> 2 H2O B. NADPH -> NADP+ + e- + H+ C. NADP+ +e- + H+ -> NADPH D. Q -> QH2 |
A. O2 + 4 e- + 4 H+ -> 2 H2O |
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A man collapses while running a marathon and is taken to the emergency room. His blood is found to be somewhat acidic and further tests show increased lactate dehydrogenase activity. This enzyme is involved in which of the following pathways? A. Anaerobic glycolysis B. Citric acid cycle C. Pentose phosphate pathway D. Gluconeogenesis |
A. Anaerobic glycolysis |
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The unique enzymes of gluconeogenesis are used to circumvent specific irrversible steps of glycolysis. Which of the following correctly pairs an enzyme from glycolysis with its corresponding enzyme(s)? A. PFK-1 / Fructose-1,6-bisphosphatase B. Pyruvate dehydrogenase / pyruvate carboxylase and PEPCK C. Hexokinase/glucokinase D. Pyruvate kinase/glucose-6-phosphatase |
A. PFK-1 / fructose-1,6-bisphosphattase |
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A fatty acid designated as 20:0 is ____, while one that is designated as 20:3 D 5,8,11 is _____. A. Simple; complex B. Comlex; simpl C. Saturated; unsaturated D. Unsaturated; saturated |
C. Saturated; unsaturated |
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Trigylcerols containing only saturated long chain fatty acids tend to remain ________ at room temperature. A. Unsaturated B. Liquid C. Solid D. Oils |
C. Solid |
Mmmmmm....butter |
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Glycerophospholipids have _____ heads and long ________ fatty acid tails. A. Polar; polar B. Polar; hydrophobic C. Hydrophobic; polar D. Hydrophobic; hydrophobic |
B. Polar heads; hydrophobic tails |
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Which is not a function of cholesterol in mammals? A. Precursor of bile salts B. Transpport of Ca2+ across membranes C. Modulate the fluidity of membranes D. Recursor of steroid hormones |
B. Transport of Ca2+ across membranes |
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Triacylglycerols cannot form lipid bilayers because they... A. Have hydrophobic tails B. Do not have polar heads C. Cannot associate with cholesterol D. Have polar heads |
B. Do not have polar heads |
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Facilitated diffusion (passive transport) through a biological membrane is... A. Generally irreversible B. Driven by the ATP to ADP conversion C. Driven by a concentration gradient D. Endergonic |
C. Driven by the concentration gradient |
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In the adenyl cyclase signaling pathway the second messenger(s) is(are)... A. ATP and GTP B. Protein kinase A C. Cyclic AMP D. AMP |
C. Cyclic AMP |
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Which is not involved in signal transduction? A. Glycolytic pathway B. Receptor tyrosine kinase C. Adenylyl cyclase pathway D. Inositol-phospholipid pathway |
A. Glycolytic pathway |
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The elongation of fatty acids is a repetition of three reactions adding carbons from __________ after each cycle until completion. A. Malonyl CoA B. Malonyl ACP C. Acetyl CoA D. Acetyl ACP |
B. Malonyl ACP 2 carbons at a time |
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Which of the following is the regulated step of fatty acid synthesis in eukaryotes? A. Carboxylation of acetyl CoA B. Transportation of mitochondrial acetyl CoA into the cytosol C. Assembly of the fatty acid chain D. All of the abovve |
A. Carboxylation of acetyl CoA ACC (Acetyl CoA Carboxylase) |
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Phosphatidate is an intermediate in the synthesis of ____________. A. Triacylglycerols and glycerophospholipids B. Gylcerophospholipids only C. Sphingolipids D. Cholesterol |
A. Triacylglycerols and glycerphospholipids |
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Fatty acids are oxidized in the.... A. Mitochondrial matrix B. Cytosol C. Endoplasmic reticulum D. Mitochondrial inner membrane space |
A. Mitochondrial matrix |
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Which of the following molecules or substances contain, or are derived from, fatty acids? A. Prostaglandins B. Sphingolipids C. Triacylglycerols D. All of the above contain or are derived from fatty acids |
D. All of the above contain or are derived from fatty acids Prostaglandins from arachadonic acid which comes from linoleate (FA) |
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Which of the lipid types listed below is most soluble in water? A. Triacylglycerols B. Glycerophospholipids C. Waxes D. Steroids |
B. Glycerophospholipids Polar head group All other are just hydrocarbons with few functional groups |
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Triacylglycerols are composed of: A. A glycerol backbond B. Three fatty acids C. Amide linkages between the fatty acids and the glycerol D. A and B above |
D. A and B above Ester linkages connect glycerol and the FAs |
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Non-steroidal anti-inflammatory drugs (NSAIDS) like asprin and ibuprofn act by blocking production of: A. Biological waxes B. Prostaglandins C. Sphingolipids D. Vitamin D |
B. Prostaglandins |
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In a typical eukaryotic plasma membrane,... A. Oligosaccharides face outwards, not toward the cytosol B. Proteins can move within the bilayer C. Lipids can move and diffuse through the bilayer D. All of the above |
D. All of the above |
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A bacteria richer in _______ can more likely live in an area of low temperature. A. Eicosanoids B. Unsaturated fatty acids C,. Saturated fatty acids D. All of the above |
B. Unsaturated fatty acids Need more unst'd bc more fluid at lower temps higher temps woulc call for sat'd fatty acids |
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What is the role of cholesterol in animal cell membranes? A. Blocks the asociation of the fatty acyl chains of phospholipids at high temperature B. Aids in the transport of small hydrophobic molecules across the membrane C. Is ta receptor site for hormones on the surface of membranes D. Broadens the temperature range of optimum membrane fluidity |
D. Broadens the temperature range of optimum membrane fluidity |
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In the mitochondria phosphate ion (PO4 3-) and H+ are transported together from the intermembrane space into the matrix. Which statement applies? A. The transport protein is a symport B. The transport protein must have a relatively large central channel to accomodate both ions C. The interior of the transport protein must be uncharged D. All of the above |
D. All of the above |
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Which is not a similarity between active transport proteins and enzymes? A. Both undergo conformational changes upon binding a substrate B. Both are susceptible to inhibition C. Both cause chemical modification to the substrate D. Both can reach a satuation limit |
C. Both cause a chemical modification to the substrate Transporters don't do that |
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Which statement is not true about G proteins? A. They are integral membrane protiens B. They are multisubunit proteins consisting of alpha, beta and gamma subunits C. They are slowly inactivated by their on GTPase activity D. They act as transducers for hormones |
A. They are integral membrane proteins |
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Protein kinase A (PKA) is: A. Affected by cyclic AMP only under unusual circumstances B. Allosterically activated by cyclic AMP C. Competitively inhibited by cyclic AMP D. Noncompetitively inhibited by cAMP |
B. Allosterically activatd by cyclic AMP 4 cAMP bind to release 2 active subunits from 4 subunit inactive state |
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Autophosphorylation of receptor tyrosine kinases depends on which of the following? A. Dimerization of the receptor B. Ligand binding C. Transmisiion of conformational changees through the membrane D. All of the above |
D. All of the above |
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The ion channel that opens in response to acetylcholine is an example of a ______ signal. A. G-protein B. Ligand-gated C. Receptor-enzyme D. Voltage-gated |
B. Ligand gated |
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Steroid hormone response elements (HREs) are _________, which, when bound to ________. Alter gene expression at the level of ________. A. Nuclear proteins, hormones; transcription B. Plasma membrane proteins; hormone; transcription C. Sequences in DNA; receptor-hormone complex; replication D. Sequences in DNA; receptor-hormone complex; transcription |
D. Sequences in DNA; receptor-hormone complex; transcription |
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Before free fatty acids can be incorporated into lipids, they must be activated to A. Eicosanoids B. Thioesters of Coenzyme A C. Acyl carrier proteins (ACP) D. NADPH |
B. Thioesters of Coenzyme A Activated for further elongation, desaturation, etc |
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Which of the following is a true statement for fatty acid oxidation? A. It occurs in the cytosol B. Oxidation requires a three carbon substrate, which transfers a two-carbon unit to the chain C. Both NADH and QH2 are produced D. None of the above |
C. Both NADH and QH2 are produced |
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Elevated levels of the hormone ________ stimulate the conversion of triacylglycerols stored in adipose cells to free fatty acids and monacylglycerols to provide energy when carbohydrate stores are depleted. A. Insulin B. Glucagon C. Epinephrine D. Ergosterol |
B. Glucagon |
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Regulation of acetyl CoA-carboxylase is accomplished by... A. Inhibition by palmityl-CoA B. Activation by citrate C. Inactivation by high levels of glucagon D. All of the above |
D. All of the above |
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*Which is not a ketone body? A. Dihydroxyacetone B. Acetoacetate C. Acetone D. Beta-dihydroxybutyrate |
A. Dihydroxyacetone |
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What is the main function of the carnitine shuttle system? A. To transport fatty acids into the mitochondrion B. To transport newly synthesized sphingolipids to the blood C. To carry cholesterol from its site of synthesis in the endoplasmic reticulum to the plasma membrane D. To aid in the assembly of chylomicrons |
A. To transport fatty acids into the mitochondrion
So they can be degraded for energy (beta oxidation) Inhibited by malonyl ACP |
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A lipoprotein particle functions to _______. A. Dissolve polar lipids for excretion B. Metabolize lipids into new substances C. Store lipids in the tissues D. Transport nonpolar lipids to body cells |
D. Transport nonpolar lipids to body cells |
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How do chylomicrons and VLDLs differ? A. Chylomicrons contain proteins, VLDLs do not B. Chylomicrons are synthesized in the intestine; VLDLs are synthesized in the liver C. Chylomicrons transport triacylglycerol, VLDLs do not D. They do not differ |
B. Chylomicrons are synthesized in the intestines; VLDLs are synthesized in the liver |
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Which of the following is/are true statement(s) about glutamine? A. It is a nitrogen donor in many biosynthetic reactions B. It is a nitrogen source for glutamate synthase C. It ccarries nitrogen and carbon between tissues, thus avoiding high toxic levels of NH4+ in blood. D. All of the above |
D. All of the above |
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Which of the following is/are true concerning transamination reactions? A. They can convert alpha-keto acids to alpha-amino acids B. All require the coenzyme pyridoxal phosphate C. The catalyzed reactions are near-equilibrium D. All of the above |
D. All of the above |
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Which of the folloing amino acids is/are derived from 3-phosphoglycerate? A. Serine B glycine C. Cysteine D. All of the above |
D. All of the above |
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Alpha-ketoglutarate is a precursor for each of the following, except... A. Glutamine B. Glutamate C. Proline D. Alanine |
D. Alanine |
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If an amino acid is glucognic, it will not be degraded to ___________. A. Pyruvate B. Glutamate C. Fumarate D. Acetoacetate |
D. Acetoacetate |
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In amino acid catabolism the alpha-amino groups are initially released as _________. A. Nitrous oxide B. Ammonium ion C. Nitrate ion D. Glutamine |
B. Ammonium ion |
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Which amino acids are purely ketogenic? A. Arginine and lysine B. Valine and isoleucine C. Tryptophan only D. Lysine and leucine |
D. Lysine and leucine |
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The glucose-alanine cycle provides a mechanism for _______tissue to eliminate nitrogen and replenish its energy supply A. Liver B. Kidney C. Muscle D. Lung |
C. Muscle |
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Which statement(s) applies (apply)to urea? A. Produced in liver B. Major solute in urine of mammals C. Compound used as a means of removing excess nitrogen D. All of the above |
D. All of the above |
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__________ is hydrolytically cleaved to directly yield urea in the urea cycle. A. Ornithine B. Glutamate C. Arginine D. Carbamoyl phosphate |
C. Arginine |
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At the subcellular level where does the urea cycle occur? A. Mitochondrial matrix only B. Mitochondrial matrix and the mitochondrial inner membrane C. Mitochondrial matrix and the cytosol D. Cytosol only |
C. Mitochondrial matrix and cytosol Matrix at the beginning and cytosol at end |
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ATPis not a nucleoside because it _________. A. Has phosphate groups B. Has three phosphates instead of just one C. Lacks the deoxyribosyl group D. Is not connected to a carbohydrate group |
A. Has phosphate groups
NucleoTides have phosphate groups |
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Purines which are found mainly in both deoxyribonucleotides and ribonucleotides are... A. Thymine and cytosine B. Adenine and guanine C. Adenine and thymine D. Guanine and cytosine |
B. Adenine and guanine |
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A ribose sugar is added to ________ rings after their synthesis and to _______ rings during their synthesis. A. Purine; pyrimidine B. Pyrimidine; purine C. Purine; purine D. Pyrimidine; pyrimidine |
B. Pyrimidine; purine |
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The first nuclotide product in the de novo biosynthetic pathway of purines is... A. AMP B. GMP C. IMP D. XMP |
C. IMP Intermediate of purine synthesis is non-traditional base IMP. Purines synthesized on ribose |
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The pureine ring system is shown below. what are the sources of nitrogen atoms 3 and 9? A. Aspartate B. Glycine C. Arginine D. Glutamine |
D. Glutamine
Glycine for 2 C and N on top CO2 for 1 carbon Tetrahydrofolate for 2 carbons Arginine for 1 N |
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Which is the source of the ribose ring in purine nucleotides? A. ATP B. AMP C. PRPP D cGTP |
C PRPP 5'-Phosphate Ribose -1 - pyrophosphate |
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Which enzyme catalyzes the step in purine nucleotide biosynthesis that is the principle site of regulation for the pathway? A. Adenylsuccinate lyase B. OPM decarboxylase C. IMP Cyclohydrolase D. Glutamine-PRPP amidotransferase |
D. Glutamine-PRPP amidotransferase |
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Which is a method by which the synthesis of AMP or GMP is regulated? A. Covalent modification B. Feedback inhibition C. Feed-forward activation D. Competitive inhibition |
B. Feedback inhibition
Adenine or Guanine go back and inhibid their respective pathway and Glutamine-PRPP amidotransferase |
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High levels of _______ will almost totally inhibit ATCase A. ADP B. ATP C. CTP and UTP D. ADP and UDP |
C. CTP and UTP Pyrimidine synthesis |
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Eukaryotic cells maintain the corrrect balance of deoxyribonucleotides needed in a species DNA by _________. A. Controlling the activity of ribonucleotid reductase B. Controlling the specificity of ribonucleotide reductase C. Controlling both the specificity and activity of ribonucleotide reductase at the same time D. Feedback inhibition |
C. Controlling both the specificity and th activity of ribonucleotide reductase at the same time Specificity site and activity site for regulation Proceed via free radical reaction |
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Dihydrofolate reductase and thymidylate synthetase are major targets for anticancer drugs because.... A. These enzymes are unique in cancer cells B. Cancer cells lack sufficient amounts of these enzymes C. Cancer cells grow rapidly and are very dependent upon the activities of these enzymes D. They donate one-carbon groups |
C. Cancer cells grow rapidly and are very dependent upon the activities of these enzymes |
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The major end product of purine degradation in humans is.... A. Allantoin B. Guanine C. Urate D. Ammonia |
C. Urate |
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Pyrimidines are catabolized to ammonia, bicarbonate, and either _______ (from cytosine or uracil) or _____ (from thymine).
A. Succinyl CoA; acetyl CoA B. Beta-alanine; beta-aminobutyrate C. Fumarate; succinyl CoA D. Acetyl CoA; succinyl CoA |
D. Acetyl CoA; succinyl CoA
Acetyl CoA - from cytosine or Uracil Succinyl CoA - from thymine |
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Regions of DNA that are most easily unwound have... A. About half G and half C B. Alternating between A and G C. Greater G:C content D. Greater A:T content |
D. Greater A: T content
Only 2 H bonds vs GC's 3 |
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In proteins, amino acids are linked by peptide bonds; in polynucleotides, nucleotides are linked by... A. Phosphoanhydride bonds B. 3'-5' phosphodiester bond C. 5'-3' phosphodiester bond D. B and C |
Phosphodiester bond Look up if interested which direction |
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"Five prime to three prime" description of a DNA strand refers to A. The phosphorylated 5' carbon at one end, the 3' at the other end B. The location of the hydroxyl group C. The phosphodiester backbone of DNA D. The phosphorylated 5' carbon on one sugar and the 3' carbon on the next sugar |
A. The phosphorylated 5' carbon at one end, the 3' at the other end |
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Supercoiling of pure circular DNA is a result of ________. A. Underwinding or overwinding of the helix B. Entanglements because of the long length of the strands C. The lack of associated histones D. The activity of exonucleases |
A. Underwinding or overwinding of the helix |
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DNA wraps around an octamer of histones to form bead-like structures called _____________. A. Nucleoids B. Nucleosomes C. Nucleoli D. Chromatids |
B. Nucleosomes |
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Which is not a difference between RNA and DNA? A. The sugar ring of RNA is more oxidized than that in DNA B. RNA contains uracil;; DNA usually does not C. RNAcannot form helices D. RNA is usually single stranded; DNA is double stranded |
C. RNA cannot form helices Sometimes it does in its secondary structure |
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The replication of DNA is ________ because __________. A. Conservative; one strand of parental DNA is retained in each daughter DNA B. Conservative; each daughter molecule has two new strands copied from the parental DNA template C. Semiconservative; one strand of parental DNA is retained in each daughter DNA D. Semiconservative; each daughter molecule has two new strands copied from the parental DNA template |
C. Semiconservative; one strand of parental DNA is retained in each daughter DNA |
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E. Coli DNA polymerase catalyzes polymerization in the _________ direction(s). A. 5' -> 3' B. 3'->5' C. 2' -> 5' D. Both 5' -> 3' and 3' -> 5' |
A. 5' to 3' |
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The 3' to 5' exonuclease activity of E. Coli DNA polymerase III acounts for the ________ of polymerization. A. Low error rate B. High speed. C. Directionality D. All of the above |
A. Low error rate Proofreading activity |
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The RNA primer at the beginning of each Okazaki fragment is removed by... A. DNA polymerase I B. DNA polymerase II C. DNA polymerase III D. 3' to 5' exonuclease subunit of DNA pol III |
A. DNA polymerase I |
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Which is not a property of RNA polymerase? A. Polymerizes in the 5' tp 3' direction B. Catalyzes the formation of phosphodiester bonds C. Polymerizes a reaction assisted by pyrophosphate hydrolysis D. Has exonuclease proof-reading activity |
D. Has exonuclease proof-reading activity |
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Which of the following is correct? A. Transcription proceeds in the 5' to 3' direction B. The template strand is copied from the 5' end to the 3' end C. RNA polymerization proceeds in th 3' to 5' direction D. None of the above |
A. Transcription proceeds in the 5' to 3' direction |
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Which is not true of the different conformations of DNA? A. Z-DNA is a left handed spiral B. A-DNA and B-DNA are right handed spirals C. A-DNA and Z-DNA segments are limited to short regions of DNA D. Both A-DNA and B-DNA are dehydrated |
D. Both A-DNA and B-DNA are dehydrated Only A DNA is dehydrated B DNA is normal, at physiological conditions |
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The tetranucleotide AGTC (in DNA) has a free hydroxyl group on... A. A B. A, G, T, and C C. C D. G, T, amd C |
C. C Free hydroxyl group only on the 3' end |
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It is easier to melt DNA richer in AT than GC because.... A. It is more heat sensitive B. There is one less hydrogen bond in an AT base pair C. The helix pitch is longer in AT rich regions D. All of the above |
B. There is one less hydrogen bond in an AT base pair |
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What is the function of DNA topoisomerases? A. Cleaving nucleotides from the ends of DNA B. Adding or removing supercoils C. Methylation of the nitrogenous bases D. Packaging of DNA into nucleosomes |
B. Adding or removing supercoils |
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Which of the following is mismatched? A. rRNA: 80% of cellular RNA B. tRNA: carry amino acids during protein synthesis C. mRNA: stable RNA carrying the coded information from DNA D. Small RNA: catalytic with or without proteins |
C. mRNA: stable RNA carrying the coded information from DNA ,mRNA is NOT stable, degrades quite quickly to avoid over expression of protein |
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Which best describes the structure of a nucleosome core particle? A. A histone octamer with DNA threaded through its center B. About 50 bp of DNA associated with one histone H1 molecule C. One nucleosome plus one histone H1 and linker DNA D. A histone octamer wrapped approximately 2 times around with DNA |
D. A histone octamer wrapped approximately two times around with DNA |
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_________ catalyze the hydrolysis of phosphodiester linkages to release nucleotide residues from only one end of a polynucleotide chain A. Topoisomerases B. Endonucleases C. Exonucleases D. Restriction enzymes |
C. Exonucleases |
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The PCR reaction mixture does not include... A. All four dNTPs B. Heat-stable polymerase C. DNA containing the sequence to be amplified D. DNA ligase |
D. DNA ligase |
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Both strands of double-stranded DNA are copied so that each daughter moecule consists of one parental strand and one newly synthesized strand. This is called _______ replication. A. Bidirectional B. Conservative C. Semiconservative D. Duplicative |
C. Semiconservative |
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Why does E. Coli need both DNApolymerase III and DNA polymerase I? A. DNA polymerase III lacks the 5' to 3' exonuclease activity needed to remove primers B. Each polymerase is specific for only one strand of DNA. DNA polymerase III acts only on the leading stand, and DNA polymerase I acts only on the lagging strand C. DNA polymerase I is needed to join the Okazaki fragments D. The DNA replication is bidirectional; one polymerase is used for each direction |
A. DNA polymerase III lacks the 5' to 3' exonuclease activity needed to remove RNA primers |
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Prokaryotic DNA polymerase III: A. contains a 5' to 3' proofreading activity to improve the fidelity of replication B. Does not require a primer molecule to initiate replication C. Has a beta subunit that acts as a clamp to improve the processivity of DNA synthesis D. Synthesizes DNA in the 3' to 5' direction |
C. Has a beta subunit that acts as a clamp to improve the processivity of DNA synthesis |
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What is the function of single-strand binding protein (SSB) (helix stabilization protein)? A. It stabilizes nicks on the lagging strand during replication until DNA ligase seals the nick B. It recognizes thymine dimers in DNA, which make the DNA single stranded, and serves as a signal for the activation of repair proteins C. It stabilizes many forms of RNA which are single stranded D. During replication it binds to single-standed regions of the lagging strand and prevents it from folding back on itself into double helical regions |
D. During replication it binds to single-stranded regions of the lagging strand and prevents it from folding back on itslef into double-helical regions |
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Which proteins are responsible for the unwinding of the double-stranded DNA during replication? A. Ligases B. Helicases C. Primases D. Lyases |
B. Helicases |
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A major difference between prokaryotic and eukaryotic DNA replication mechnisms is... A. No Okazaki fragments are made in eukaryotes B. Both leading and lagging strands are continuous in eukaryotes C. No primer synthesis is needed in eukaryotes D. The replication fork moves slower in eukaryotes |
D. The replication fork moves slower in eukaryotes |
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The general excision repair pathway for DNA repair has the following order... A. Endonuclease cuts -> helicase or endonuclease removes -> DNA polymerase -> DNA ligase B. DNA ligase -> DNA polymerase -> helicase or endonuclease removes -> endonuclease cuts C. Endonuclease cuts -> DNA polymerase repairs -> helicase opens up -> DNA ligase D. Endonuclease cuts -> DNA ligase removes -> endonuclease rempves -> DNA ligase |
A. Endonucleasae cuts -> helicase or endonuclease removes -> DNA polymerase -> DNA ligase |
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In base excision repair, the first enzyme to act is: A. DNA polymerase B. DNA ligase C. AP endonuclease D. DNA glycosylase |
D. DNA glycosylase Cleaves N-glycosidic bond |
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In the Holliday model describing recombination... A. Homologous sequences line up B. DNA strands associate with the homologous strand ("strand invasion") C. Strands rotate then are cleaved at the crossover point D. All of the above |
D. All of the above |
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Which is not a property of RNA polymerase? A. Polymerizes in the 5' to 3' directon B. Catalyze the formation of phosphodiester linkages C. Polymerizes a reaction assisted by pyrophosphate hydrolysis D. Has exonuclease proof-reading activity |
D. Has exonuclease proof-reading activity |
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The template strand of DNA is copied by RNA polymerase from... A. Both 3' to 5' and 5' to 3' emds B. 5-10 nucleotides before the +1 transition state C. 3' to 5' D. 5' to 3' |
C. 3' to 5' The RNA is 5' to 3' and the DNA template is antiparallel |
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After binding by E Coli RNApolymerase, the correct order of events for transription initiation is: A. Start of RNA synthesis, open complex formation, closed complex formation, promotor clearance B. Closed complex formation, open complex formation, start of RNA synthesis, promotor clearance C. Open complex formation, closed complex formation, start of RNA synthesis, promotor clearance D. Start of RNA synthesis, closed complex formation, open complex formation, promotor clearance |
B. Closed complex formation, open complex formation, start RNA synthesis, promotor clearance |
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The sigma factor of E. Coli RNA polymerase: A. Combines with the core enzyme to confer specific binding to a promotor B. Is inseparable from the core enzyme C. Is required for termination of an RNA chain D. Will catalyze synthesis of RNA from both DNA template strands in the absence of the core enzyme |
A. Combines with the core enzyme to confer specific binding to a promotor |
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Which of the following is not a known function of TFIIH? A. DNA helicase activity B. Hydrolysis of AtP C. Formation of open complex D. Termination of transcription |
D. Termination of transcription |
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Which statement is false concerning the general transcription factor TFIID? A. It binds to the promotor B. Its TBP subunit binds to the region containing the TATA box C. It is the RNA polymerase II initiation factor D. None of the above |
D. None of the above |
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Which statement is true about the relative number of accessory proteins necessary for RNA polymerization in eukaryotes versus E. Coli? A. Eukaryotes require many more accessory proteins B. They require about the same number of accessory proteins C. Eukaryotes require far fewer accessory proteins D. The number required varies widely by species. Some eukaryotes require less than E. Coli and some require more |
A. Eukaryotes require many more accessory proteins [for RNA polymerization] |
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The sigma70 subunit in E. Coli RNA polymerase acts as a(n)__________. A. Represor B. Sliding clamp C. Helicase D. Initiation factor |
D. Initiation factor Help with promotor binding |
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Which of the following is true about transcription? A. A repressor protein activates transcription of a negatively regulated gene B. A positively regulated gene can be transcribd only in the absence of an active repressor C. In the absence of an activator, a negatively regulated gene is poorly transcribed D. The initiation of transcription of regulated genes is controlled by regulatory proteins which bind to specific DNA sequences |
D. The initiation of transcription of regulated genes is controlled by regulatory proteins which bind to specific DNA sequences |
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When a repressor protein is ________ (bound, unbound) to a promoter region transcription is allowed; when an activator is _______(bound, unbound) to a promoter transcription is stimulated. A. Bound, unbound B. Unbound; bound C. Bound; bound D. Unbound; unbound |
B. Unbound; bound |
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An operon is ________ . A. A set of genes whose transcription is controlled by a single promotor B. The site of repressor binding C. A protein that activates the trascription of a whole class of genes D. A multisubunit complex responsible for the splicing of exons |
A. A set of genes whose transcription is controlled by a single promoter |
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Which statement is false about the utilization of lactose as a carbon source by E. Coli? A. In the presence of both glucose and lactose, the enzymes necessary for lactose catabolism are produced only in limited amounts B. Lactose is the inducer for the enzymes responsible for its own catabolism C. In the absence of lactose, the repressor binds to a single site upstream of the lac genes D. The catabolic enzymes are encoded in a three-gene operon controlled by a single promoter |
C. In the absence of lactose, the repressor binds to a single site upstream of the lac genes Binds to two sites O1 and O2 |
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Consider the lac operon of E. Coli. When there is neither glucose nor lactose in the growth medium: A. The operon is fully induced B. The repressor is bound to the lac operator C. CRP protein binds to the lac operator D. RNA polymerase binds the lac promoter and transcribes the lac operon |
B. The repressor is bound to the lac operator Look into the CRP protein - I believe that it will bind if there is low glucose concentrations and activate transcription but will not be able to activate if repressor present but can still bind |
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The binding of CRP (cAMP receptor protein of E. Coli) to DNA in the lac operon: A. Assists RNA polymerase binding to the lac promoter B. Is inhibited by a high level of cAMP C. Occurs only when glucose is present in the growth medium D. Prevents the repressor from binding to the lac operator |
A. Assists RNA polymerase binding to the lac promoter
Glucose present in low concentrations generates high levels of cAMP which activate CRP |
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Which one of the following statements about eukaryotic versus prokaryotic gene regulation is not correct? A. Access to eukaryotic promoters is restricted by the structure of chromatin B. Most regulation is positive, involving activators rather than repressors C. Transcription and translation are separated in both space and time D. Strong promoters in eukaryotes are generally fully active in the absence of regulatory proteins. |
D. Strong promoters in eukaryotes are generally fully active in the absence of regulatory proteins FALSE FALSE FALSE ** |
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Which is not a feature of eukaryotic mRNA procesing? A. Addition of a 5'-5' triphosphate linkage to GTP B. Methylation of the terminal CCA triad C. Addition of a polyA tail to the 3' end D. Removal of intron sequences |
B. Methylation of the terminal CCA triad CCA triad in tRNA (still doesn't get methylated, it gets bonded to amino acid) |
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The large RNA -protein complex that processes introns and exons is called ________ . A. The replisome B. The catalytic RNA complex C. The spliceosome D. RNA ligase |
C. The spliceosome |
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A branched ("lariat") structure is formed during: A. Attachment of a 5' cap to mRNA B. attachment of polyA tails to mRNA C. Processing of preribosomal RNA D. Splicing of introns |
D. Splicing of introns |
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Of alll the possible triplet codons, ______ do not code for an amino acid. A. 0 B. 1 C. 2 D. 3 |
D. 3 Stop codons |
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Use the table below to determine whcih RNA templat strand DNA sequence (written in the 5' to 3' direction) specifies the tripeptide with the sequence gly-ala-leu. A. GGGGCTCTCB. CTCTCGGGGC. CCCCGAGAGD. GAGAGCCCC |
D. GAGAGCCCCwatch 5' to 3' direction |
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Which statement is true about the number of initiation and STOP codons? A. One initiation codon; one STOP codon B. One initiation codon; multiple STOP codons C. Multiple initiation codons; one STOP codon D. Multiple codons for both initiation and STOP |
B. One initiation codon; multiple STOP codons |
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The initiation codon _______ . A. Specifies uracil B. Specifies methionine C. Binds a protein complex that starts translation D. Is part of the TATA box |
B. Specifies methionine |
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The unambiguity and degeneracy of the genetic code can best be respectively exepmlified by which of the following? A. UUU and UUC both code for Phe; UUU codes only for Phe B. UUU codes only for Phe; UUU and UUC both code for Phe C. UUU codes for bothPhe and Ser; UUU and UUC both code for Phe and Ser D. UUU and UUC both code for Phe and Ser; UUU codes for both Phe and Ser |
B. UUU codes only for Phe; UUU and UUC both code for Phe Degenerate - Multiple codons for one amino acid Unambiguous - one codon specifies one amino acid |
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The anticodon of tRNAala can bind to three different codons for alanine (GCU, GCC and GCA) bcause... A. There are different bases at the 5' position of the anticodon B. There are different bases at the 3' end position of the anticodon C. The base at the 5' position of the anticodon is I and is the wobble position D. The base at the 3' position of the anticodon is I and is the wobble position |
C. The base at the 5' position of the anticodon is I and is the wobble position
Anticodon antiparallel to codon, 3rd base is wobble base |
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Amino acids are attacehd to tRNA at the _________ . A. Anticodon region B. 5' end C. 3' end D. Variable arm |
C. 3' end CCA sequence |
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Which help cells avoid mis-insertion of amino acids in protein synthesis? A. The specificity of codon:anticodon interaction B. The specificity of tRNA:amino acid pairs C. The proofreading ability of tRNA synthetase D. All of the above |
D. All of the above tRNA synthetase - specific due to charge, size, hydrophobicity - will reject too large and cleave too small |
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At the ribosome the template mRNA is translated in the _______ direection, while the protein is synthesized in the _____direction. A. 5' to 3' ; N-terminal to C-terminal B. 5' to 3' : C-terminal to N-terminal C. 3' to 5'; N-terminal to C-terminal D. 3' to 5'; C-terminal to N-terminal |
A. 5' to 3'; N-terminal to C-terminal |
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The deaminoacylated tRNA leaves the ribosome as the growing polypeptide passes through the tunnel of the large ribosomal subunit from the _______ . A. 30S or 40S subunit B. Protein factors C. E site D. P site |
C. E site In eukaryotes, directly from P site |
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The first amino acid incoporated into proteins _______ . A. Can be any of the 20 standard amino acids B. Is an N-formylmethionine in E. Coli and methionine in other organisms C. Is always inosinate D. Is an amidated methionine residue that is cleaved following termination of translation |
B. Is an N-formylmethionine in E. Coli and methionine in other organisms |
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Which of the following is mismatched? A. Initiator tRNA - recognizes AUG codons during initiation at the P site B. Shine-Dalgarno sequence - upstream of the initiator codon and plays a role in initiation C. Anti-Shine-Dalgarno sequence - pyrimidine-rich stretch at the 3' end of 16S rRNA D. Eukaryotic initiation factors - IF-1, IF-2, IF-3 |
D. Eukaryotic initiation factors - IF-1, IF-2, IF-3 |
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The correct order for the formation of the prokaryotic 70S initiation complex is: A. 50S -> IF-1, IF-2 -> mRNA -> fMet-tRNAfmet -> 50S B. 30S -> IF-1, IF-3 -> fMet-tRNAfmet -> IF-2 -> mRNA -> 50S C. 30S -> IF-1, IF-3 -> IF-2 -> fMet-tRNAfmet -> mRNA -> 50S D. 30S -> IF-1, IF-2 -> IF-3 -> fMet-tRNAfmet -> mRNA -> 50S |
C. 30S -> IF-1, IF-3 -> IF-2 -> fMet-tRNAfmet -> mRNA -> 50S |
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Chain elongation consists of three steps: (1) positioning the correct aminoacyl-tRNA to the A site, (2) forming the peptide bond and (3) ___________. A. Dissociation of the 30S and 50S subunits B. Removal of the fMet-tRNAfmet from the complex C. Moving the mRNA along one codon D. All of the above |
C. Moving the mRNA along one codon Translocation |
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Translation begins to be terminated when... A. Three release factors appear at the ribosome complex B. Three release factors enhance the hydrolysis of the peptide C. An fMet tRNA codon is in the mRNA D. A termination codon is in the mRNA |
D. A termination codon is in the mRNA |
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