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Q:
All are true for the DNA strand-exchange reaction EXCEPT:
a. ATP-dependent.
b. catalyzed by RecA protein.
c. requires DNA polymerase I.
d. complex has 3'-terminal ssDNA affinity for other DNA termini.
e. results in branch migration.
Q:
In general recombination in E. coli, the protein that binds ssDNA forming a nucleoprotein filament capable of strand invasion and homologous pairing is:
a. RecA.
b. RuvB.
c. RuvC.
d. RuvA.
e. RecBCD complex.
Q:
One function of the RecA protein in recombination events is to:
a. produce an endonucleolytic nick on dsDNA.
b. aid in recognition of Chi site by the RecBCD complex.
c. initiate recombination.
d. catalyze the ATP-dependent DNA strand exchange reaction.
e. drive branch migration and process the Holliday junction into recombinant products.
Q:
The protein that moves along dsDNA using ATP-dependent helicase and nuclease activity during general recombination in E. coliis:
a. RecA.
b. RuvB.
c. DNA polymerase I.
d. DNA ligase.
e. RecBCD complex.
Q:
The correct sequence for homologous recombination steps is:
A. ligation.
B. branch migration and strand exchange.
C. nicking.
D. EW or NS cleavage, resolution and re-ligation.
E. strand invasion.
a. B, C, E, A, D
b. C, B, E, D, A
c. D, C, B, A, E
d. C, E, A, B, D
e. C, A, B, E, D
Q:
All of the following are true of prion diseases include all EXCEPT:
a. they include "mad cow disease".
b. they are genetic and infectious.
c. their occurrence may be sporadic.
d. they are dominantly inherited.
e. all are true.
Q:
Prions are defined as:
a. ions with an inappropriate number of protons.
b. ions about to form.
c. ionic proteins that bind DNA.
d. proteinaceous infectious particles.
e. particle ions that bind proteins.
Q:
Compared to their parents, progeny may have new combinations of traits because of:
a. reverse transcriptase.
b. cyclin dependent protein kinase.
c. genetic recombination.
d. processivity.
e. all are true.
Q:
AZT (3'-azido-2',3'-dideoxythymidine) is a drug that gets incorporated into growing viral DNA and blocks the activity of:a. DNA ligase.b. DNA polymerase (beta).c. DNA polymerase (alpha).d. reverse transcriptase.e. none of the above.
Q:
Reverse transcriptases possess all of the following activities EXCEPT:
a. RNA-directed DNA polymerase activity.
b. RNase H activity.
c. ssDNA-directed DNA polymerase activity.
d. dsDNA-directed DNA polymerase activity.
e. all are true.
Q:
All are characteristics of RNA-directed DNA polymerase EXCEPT:
a. synthesizes polynucleotides in the 5' to 3' direction.
b. often uses a specific tRNA primer.
c. found in retroviruses.
d. also called reverse transcriptase.
e. all are true.
Q:
All are characteristic of retroviruses EXCEPT:
a. uses viral DNA as a template.
b. reverse transcriptase is required to produce dsDNA for insertion into host genome
c. the viral RNA genome is degraded prior to complete synthesis of dsDNA
d. reverse transcriptase is often error-prone causing viruses to mutate quickly
e. genome can lie dormant for years as a provirus in the host chromosome.
Q:
An RNA-dependent DNA polymerase that carries the RNA template with it to synthesize repeats at the 3'-ends of chromosomes is called:a. DNA ligase.b. telomerase.c. DNA polymerase (gamma).d. topoisomerase.e. DNA polymerase (beta).
Q:
Telomeres have all of the characteristics EXCEPT:a. G-rich nucleotide sequences.b. structures at the end of eukaryotic chromosomes.c. eukaryotic counterpart to the prokaryotic -complex.d. short (5-8 bp) tandemly repeated sequences.e. all are true.
Q:
The principal DNA polymerase in eukaryotic leading strand DNA replication is:
Q:
In eukaryotic cells, one of the protein kinases that acts on the pre-replication complex (pre-RC) to trigger DNA replication is:
a. ORC.
b. MCM.
c. Cdc6p.
d. RLF.
e. cyclin B-CDK.
Q:
In the initiation of replication in yeast, the pre-replication complex (pre-RC) consists of all EXCEPT:
a. MCM complex.
b. Cdc6p.
c. ORC.
d. CDKs.
e. all are true.
Q:
Progression through the cell cycle for eukaryotic cells is regulated through a series of ____ that depend on ____, produced at one phase and degraded at another, that bind ____ which regulate specific proteins by phosphorylation.
a. checkpoints; cyclins; cyclin dependent protein kinases (CDKs)
b. cyclins; phosphorylation; protein kinases
c. phosphorylations; cyclins; protein kinases
d. CDKs; cyclins; protein kinases
e. none are true
Q:
Eukaryotic cells have replication regions called ____ that occur every ____ kbp and the units of replication are called ____.
a. replicons; 2-5; replication forks
b. replication factories; 5-10; replicons
c. replicators; 3-300; replicons
d. replication forks; 5-50; replicators
e. none are true
Q:
The termination of DNA replication in E. colioccurs when ____ protein binds the ____ locus on the DNA and acts as a ____.
a. tag; oriC; helicase
b. ter; tag; polymerase
c. DnaC; DnaG; gyrase
d. Tus; Ter; contrahelicase
e. SSB; primer; RNA polymerase
Q:
The enzyme that seals nicks in dsDNA where a 3'-OH and 5'-phosphate are juxtapositioned is:
a. DNA polymerase I.
b. DNA gyrase.
c. DNA polymerase III.
d. DNA ligase.
e. primerase.
Q:
Removal of RNA primer and replacement with DNA is carried out by:
a. DNA polymerase I.
b. DNA gyrase.
c. DNA polymerase III.
d. DNA ligase.
e. primerase.
Q:
All occur during DNA replication in E. coliEXCEPT:
a. helicase unwinds dsDNA at the replication fork.
b. DNA ligase catalyzes the formation of phosphoester bonds on the lagging strand.
c. DNA polymerase I hydrolyzes RNA from the 5' ends of Okazaki fragments.
d. primase (DnaG) binds to a GC rich region of dsDNA in oriC.
e. all are true.
Q:
A pair of -subunits of DNA polymerase III form a ____ to tether the polymerase to the template thus increasing the ____ of the polymerase.a. ligase; unwindingb. sliding clamp; processivityc. primer binding; primase activityd. loop of DNA; directione. none are true
Q:
All are properties of DNA polymerase III EXCEPT:
a. It is responsible for incorporating most of the nucleotides in the lagging strand.
b. It synthesizes most of the leading strand prior to aiding in the synthesis of the lagging strand.
c. It contains a 3' to 5' exonuclease activity.
d. It is a large protein complex containing more than five subunits.
e. Much greater processivity than DNA polymerase I.
Q:
The enzyme that removes the RNA primer from the Okazaki fragment is:
a. DNA polymerase I.
b. DNA ligase.
c. helicase.
d. DNA polymerase III.
e. DNA gyrase.
Q:
3'-Exonuclease activity of DNA polymerase I of E. colihas all the characteristics EXCEPT:
a. is an "editor" of polymerase activity.
b. is opposite to the polymerase activity.
c. removes nucleotides that do not base pair at the 3'-end of the growing chain.
d. is relatively fast compared to the polymerase activity.
e. all are true.
Q:
E. coliDNA polymerase I has ____ distinct catalytic active site(s) on its single polypeptide chain.
a. 1
b. 2
c. 3
d. 4
e. 5
Q:
The degree to which the enzyme remains associated with the template through successive cycles of nucleotide addition is referred to as:
a. processivity.
b. turn-over number.
c. progression.
d. semidiscontinuousness
e. dissociativity.
Q:
E. coliDNA polymerase I has all of the following characteristics EXCEPT:
a. a 5'ï‚®3' exonuclease activity.
b. a 3'ï‚®5' exonuclease activity.
c. a 5'ï‚®3' DNA polymerase activity.
d. modest processivity (approximately 20 nucleotides).
e. does not require a primer for initiation.
Q:
DNA polymerases share all of the following characteristics EXCEPT:
a. incoming bases are paired with corresponding bases on the template strand within the polymerase active site
b. polymerization proceeds in a 5'ï‚®3' direction
c. polymerization is antiparallel to template strand
d. strong processivity
e. polymerization is dependent upon the presence of an oligonucleotide primer
Q:
All are characteristics of Okazaki fragments EXCEPT:
a. newly synthesized short lagging strand fragments.
b. synthesis performed in the 5'ï‚®3' direction.
c. initiated with an RNA primer.
d. about 20-30 nucleotides in length.
e. binds anti-parallel to the template strand.
Q:
Which of the following is NOT true regardingE. colireplication on the lagging strand?
a. is primarily carried out by DNA polymerase I.
b. synthesized discontinuously.
c. performed in a 5'ï‚®3' direction of synthesis
d. initially synthesized as Okazaki fragments
e. requires the enzymes primase and DNA ligase
Q:
SSBs are:
a. substrates for DNA ligases.
b. supercoil stabilizing bodies.
c. single-stranded bodies called Okazaki fragments.
d. single-stranded DNA binding proteins that prevent re-annealing.
e. nucleases that hydrolyze single-stranded RNA primers.
Q:
All are correct about DNA gyrase in E. coliEXCEPT:
a. It is a topoisomerase that hydrolyzes ATP during its reaction mechanism.
b. Its mechanism involves the breaking of a single phosphoester bond in one strand of dsDNA.
c. It works to remove positive supercoiling introduced by the DnaB protein (helicase).
d. It works to introduce negative supercoiling in DNA to overcome the torsion stress imposed upon unwinding.
e. All are true.
Q:
Enzymes that catalyze the unwinding of DNA double helix are:
a. topoisomerases.
b. helicases.
c. ligases.
d. gyrases.
e. polymerases.
Q:
All of the following are characteristic of replication of the E. colicircular chromosome EXCEPT:
a. replication is bi-directional.
b. it initiates at a unique position called oriC.
c. torsional stress introduced in the duplex DNA is relieved by DNA gyrase.
d. the unwinding of the duplex DNA is driven by the translocation of the DNA polymerase.
e. replication forks move in opposite directions.
Q:
DNA is replicated by a ____ mechanism.
a. dispersive
b. conservative
c. semiconservative
d. liberal
e. none of the above
Q:
All of the following are paired with their preferred substrate EXCEPT:
a. brain: glucose
b. heart: fatty acids
c. resting skeletal muscle: glucose
d. anaerobic skeletal muscle: glucose
e. adipose tissue: fatty acids
Q:
A constant availability of fuels in the blood is called ____ and the order of preference for fuel usage is ____.
a. phosphorylation potential; glycogen> triacylglycerols> protein
b. fuel dynamics; triacylglycerols> glycogen> protein
c. metabolic regulation; triacylglycerols> glycogen> protein
d. caloric homeostasis; glycogen> triacylglycerols> protein
e. none are true
Q:
Which of the following enzymes is activated upon phosphorylation by AMP activated protein kinase?
a. acetyl CoA carboxylase
b. phosphofructokinase-2
c. glycogen synthase
d. 3-hydroxy-3-methylglutaryl-CoA reductase
e. none of the above
Q:
The energy charge of healthy living cells is in the neighborhood of ____.
a. 0.55-0.60
b. 0.60-0.65
c. 0.65-0.75
d. 0.75-0.85
e. 0.85-0.88
Q:
An energy charge (EC) of 0.9 is roughly 80% ATP, 17% ADP and 3% AMP. At this EC, ____ enzyme activities are low and ____ enzyme activities higher.
a. ATP generating; ATP utilizing
b. ATP generating; NADH producing
c. ATP utilizing; ATP generating
d. ATP utilizing; NADH producing
e. NADH producing; ATP generating
Q:
Regulatory enzymes, such as ____, in energy-producing pathways show greater activity at ____ energy charge.
a. fructose-1,6-bisphosphatase; low
b. acetyl-CoA carboxylase; low
c. pyruvate kinase; high
d. PFK-1; low
e. none of the above
Q:
All are true for the energy charge (EC) of a cell EXCEPT:
a. It is an index of adenylate phosphoric anhydrides.
b. EC has a range of 0 to 1.0.
c. It is a ratio of adenylate phosphoric anhydride bonds to total adenylate concentration.
d. It is 1.0 when all of the adenylate is ATP.
e. It is rapidly changed by adenylate kinase.
Q:
The reaction, ATP + AMP ï‚®2ADP, is catalyzed by:
a. adenylate phosphorylase.
b. AMP-phosphotransferase.
c. ADP mutase.
d. adenylate kinase.
e. none are true.
Q:
The two metabolic roles served by ATP are:
a. promoting increased reaction speed and dephosphorylation.
b. changing both Km and Vmax.
c. allosteric regulation and stoichiometric involvement.
d. preventing futile cycles and changing Km.
e. none of the above.
Q:
Which of the following statements is true for ATP stoichiometry in metabolic pathways?
a. It is a consequence of evolution, only.
b. A singular number is not required, only.
c. It results from biological adaptation, only.
d. It cannot be predicted from any chemical considerations, only.
e. All are true
Q:
The overall thermodynamic efficiency of metabolism is determined through reaction-coupling with:
a. NADH oxidation.
b. CO2 release.
c. reduction of O2.
d. ATP hydrolysis and synthesis.
e. glucose oxidation.
Q:
In photoautotrophs, ____ are fed into catabolism to generate the metabolic intermediates needed to supply ____.
a. lipids; photorespiration
b. proteins; photorespiration
c. carbohydrates; anabolism
d. carbohydrates; NADPH
e. proteins; NADPH
Q:
____ and ____ are unique in that they are the only compounds whose purpose is to couple the energy-yielding processes of ____ to the energy-consuming reactions of ____.
a. NADH; ATP; catabolism; anabolism
b. ATP; [FADH2]; catabolism; anabolism
c. [FADH2]; NADH; anabolism; catabolism
d. ATP; NADPH; catabolism; anabolism
e. ATP; NADPH; anabolism; catabolism
Q:
____ is the principal energy source for protein synthesis, ____ for phospholipid synthesis, and ____ for polysaccharide synthesis.
a. UTP; GTP; CTP
b. GTP; CTP; UTP
c. CTP; UTP; GTP
d. UTP; CTP; GTP
e. CTP; GTP; UTP
Q:
All are major components of anabolic pathways EXCEPT:
a. NADH.
b. glycolysis and citric acid cycle intermediates.
c. ATP, GTP, CTP, UTP.
d. NADPH.
e. all are true.
Q:
Which of the following metabolic pathways is strictly anabolic?
a. glycolysis
b. gluconeogenesis
c. citric acid cycle
d. pentose phosphate cycle
e. ï¢-oxidation of fatty acids
Q:
Leptin is an important hormone that indicates a generally satisfactory amount of metabolites available in the body. Which of the following is true regarding leptin?
a. Leptin is produced in adipose tissue in response to the presence of large amounts of triacylglycerols
b. One of the results of leptin production is the increase in thermogenesis in adipose tissue brought about through an increase in the expression of thermogenin
c. The primary site of leptin's action is upon the hypothalamus where it ultimately results in the release of norepinephrine
d. All of the above are correct
e. A and C are correct
Q:
Under conditions where glucose levels are high and acetyl CoA is needed for fatty acid synthesis, which of the following pathways would NOT be active in adipose tissue?
a. Pentose phosphate pathway
b. Glycogen synthesis
c. Glycolysis
d. Glycerol synthesis from DHAP
e. All of the above would be active
Q:
Energy balance in the cell (ATP/ADP/AMP levels) is an important factor in the metabolic pathways we have studied. How does this regulation take place?
a. ATP, ADP and/or AMP bind to DNA to modulate transcription of genes for enzymes involved in metabolism
b. ATP, ADP and/or AMP bind to enzymes involved in metabolism, allosterically changing the enzyme activity
c. High levels of ATP result in nonenzymatic phosphorylation of the enzymes involved in metabolism, changing their activity
d. High levels of ATP result in excessive production of cyclic AMP, causing activation of pathways such as glycogenolysis and gluconeogenesis
e. None of the above
Q:
During prolonged fasting (more than 48 hours), which of the following would show a dramatically increased concentration in the blood?
a. glucose
b. fatty acids
c. ketone bodies
d. lipoproteins
e. none of the above
Q:
During the feeding phase, which of the following pathways would be inhibited in the liver?
a. glycogen synthesis
b. fatty acid synthesis
c. pentose phosphate pathway
d. gluconeogenesis
e. none of the above
Q:
During the fasting phase, which of the following events occurs?a. release of hormones such as gastrin and cholecystokininb. release of insulin by the pancreatic -cellsc. activation of lipolysisd. production of glycogene. none of the above
Q:
Of the following, which tissue is correctly described?
a. brain: use of glucose and fatty acids as fuel
b. pancreas: production of insulin and glucagon
c. adipose tissue: storage of carbohydrates and triacylglycerols
d. liver: overall control of metabolism through hormone production
e. none of the above are correct
Q:
Which of the following comments regarding resveratrol is INCORRECT?
a. produced in plants, particularly in grape skins, in response to stress
b. activates SIRT1 NAD+-dependent deacetylase activity
c. inhibits AMPK in the brain
d. has many of the same effects as caloric restriction
e. all of the above are correct
Q:
Ethanol metabolism in liver is characterized by all of the following EXCEPT:
a. decreased pH levels due to lactic acidosis.
b. two oxidation steps to convert ethanol to acetate, both reactions produce NADH.
c. decreased gluconeogenesis activity resulting in hypoglycemia.
d. decreased NADH/NAD+ ratio in the cell.
e. increased acetaldehyde-protein adducts impairing protein function.
Q:
Which of the following hormones that governs eating behavior is INCORRECTLY defined?
a. insulin: stimulation of adipocyte leptin production
b. leptin: appetite suppression when levels are high
c. ghrelin: released from stomach in response to food to further stimulate appetite
d. cholecystokinin: released from the intestines during eating to signal satiety
e. all are correct
Q:
All are characteristics of leptin EXCEPT:a. it binds to hypothalamus, inhibits release of neuropeptide-Y and is thus an anorexic agent.b. it is a signal molecule that limits food intake and increases energy expenditure.c. it communicates the status of triacylglycerol levels in the adipocytes to the central nervous system.d. if leptin levels are low, appetite is suppressed; and if leptin levels are high, appetite is increased.e. it induces synthesis of -oxidation enzymes and increases expression of uncoupler protein-2 (UCP-2) to increase thermogenesis.
Q:
In addition to carbohydrate and lipid energy metabolism, the liver serves other purposes EXCEPT:
a. producing insulin to regulate metabolism.
b. converting amino acids into metabolic fuel.
c. ketone body production.
d. detoxification of poisons and drugs.
e. Gluconeogenesis.
Q:
All are uses of glucose-6-phosphate in liver EXCEPT:
a. catabolized to acetyl-CoA for fatty acid biosynthesis.
b. generate NADPH and pentoses.
c. released as glucose to blood stream.
d. converted to glycogen.
e. all are true.
Q:
All are characteristics associated with "brown fat" EXCEPT:
a. high levels of mitochondria rich in cytochromes.
b. presence of uncoupler protein-1, thermogenin, in the mitochondrial inner membrane.
c. energy from oxidation is converted to heat.
d. found in newborns and hibernating animals.
e. all are characteristics.
Q:
Fatty acids are released from adipocytes when:
a. insulin levels are high.
b. glycerol-3-phosphate levels are high.
c. adipose ATP levels are high.
d. blood glucose levels are low.
e. none are true.
Q:
Adipocytes lack the enzyme ____ and thus require DHAP for triacylglycerol synthesis.
a. DHAP reductase
b. glycerol kinase
c. acyldihydroxyacetonephosphate transferase
d. DHAP acyltransferase
e. carnitine acyl transferase
Q:
Glucose is pivotal to adipocyte metabolism in all areas EXCEPT:
a. forms DHAP for reduction and esterification of fatty acids.
b. provides glucose-6-phosphate for generating NADPH from the pentose phosphate pathway.
c. synthesizes ketone bodies.
d. converts glucose to fatty acids for storage and export.
e. all are true.
Q:
Energy metabolism in the heart is characterized by all of the following EXCEPT:
a. the preferred fuel is fatty acids.
b. it has minimal energy reserves.
c. it is unusually rich in mitochondria.
d. the heart consumes over 90% of the total oxygen supply during maximal physical exertion.
e. the range of activity is much less than that in muscle (200 fold).
Q:
Heart muscle differs from skeletal muscle in the following ways EXCEPT:
a. heart is completely aerobic.
b. heart prefers fatty acids as fuel.
c. heart has more phosphocreatine than skeletal muscle.
d. heart has limited quantities of glycogen.
e. all are true.
Q:
Under strenuous aerobic exercise, which of the following would be true for skeletal muscle?
a. only glucose will serve as a fuel source
b. only fatty acids will serve as a fuel source
c. both glucose and fatty acids will be used as fuel with the use of glucose increasing with the intensity of the exercise
d. both glucose and fatty acids will be used as fuel with the use of fatty acids increasing with the intensity of the exercise
e. none of the above
Q:
During strictly anaerobic exercise, muscle cells preferentially:
a. carboxylate pyruvate to oxaloacetate.
b. oxidize pyruvate to acetyl-CoA.
c. decarboxylate pyruvate to acetaldehyde.
d. reduce pyruvate to lactate.
e. none of the above.
Q:
All of the following are fuels for contracting muscles during strictly anaerobic metabolism EXCEPT:
a. ATP.
b. creatine phosphate.
c. glycogen.
d. glucose.
e. palmitic acid.
Q:
Muscle contractions occur when a motor nerve impulse causes ____ release from specialized compartments, that bind to ____, a regulatory protein initiating events that result in sliding of ____ thick filaments along ____ thin filaments.a. Fe++; myoglobin; actin; myosinb. Na+; troponin C; IGG; actinc. Ca++; troponin C; myosin; actind. Ca++; calmodulin; PKC; PLCe. K+; Na+/K+ ATPase; subunit-; subunit-
Q:
During fasting or starvation, the brain:a. converts endogenous fatty acids into -hydroxybutyrate.b. utilizes -hydroxybutyrate from the blood stream.c. utilizes amino acids for fuel from degradation of brain protein.d. utilizes its glycogen stores as a first responding source of fuel.e. all of the above.
Q:
The brain prefers to use ____ as fuel, but under prolonged fasting or starvation it adapts to use ____.a. fatty acids; glucoseb. glucose; -hydroxybutyratec. glycogen; fatty acidsd. glucose; fatty acidse. -hydroxybutyrate; amino acids
Q:
All are characteristics of brain tissue EXCEPT:
a. 2% or so of body mass.
b. 20% of oxygen consumed by brain.
c. oxygen consumption is independent of mental activity.
d. has no significant fuel reserves.
e. all are true.