Chem TB Flashcards Unit 2
1) If tandem mass spectrometry is combined with a chromatographic separation, what is added to the physical property characterization of the compound being analyzed? / Retention time2) In what mass spectrometers does the fragmentation of ions take place after they have been separated by their m/z value in a first stage? / In a tandem mass spectrometer
3) What is the function of the vacuum system in a mass spectrometer? / To keep ions from colliding during interactions with the magnetic or electric fields
4) In regard to mass spectrometry, what is a molecular ion? / It is the unfragmented ion of the original molecule being studied.
5) How is trapping-type spectrometry different from typical beam-type mass spectrometry? / Trapping-type mass spectrometry uses an ion trap designed to collect ions in three dimensions instead of two dimensions as in a typical beam-type mass spectrometer.
6) You would like to offer a service to the researchers in your institution for identification and quantitative analysis of proteins produced by microorganisms in liquid media using your HPLC-mass spectrometer system. Which one of the ionization techniques is best suited for this analysis? / Electrospray
7) You would like to offer a service to the researchers in your institution for identification and quantification of organic acids produced by microorganisms using your gas chromatograph-mass spectrometer system. Before selecting an ionization technique, you choose to run trial samples with electron and chemical ionization. You notice that the m/z of the acidic ions produced by chemical ionization is higher than the m/z produced using electron ionization. What is the cause of this disparity? / Organic acids are not fully fragmented by chemical ionization, yielding a higher mass number.
8) In a mass spectrometer, ion detection is typically accomplished through the use of an electron multiplier. This involves: / a chain of dynodes that “multiplies” the number of electrons to provide a detectable signal.
9) What type of mass spectrometer uses radio frequency–generated fields to confine ions in three dimensions? / Quadrupole ion trapping-mass spectrometer
10) An example of a clinical application of an HPLC coupled to a tandem mass spectrometer would be: / screening and confirming the presence of inborn errors of metabolism.
11) In a mass spectrometer, the ion with the highest abundance in the mass spectrum that is assigned a relative abundance of 100% is referred to as the: / base peak.
12) The soft ionization technique that uses a UV-absorbing compound upon which the analyte of interest is placed and eventually vaporized into a plume of ions directed into the mass analyzer is: / matrix-assisted laser desorption ionization.
13) Because of the ability to identify and quantify proteins in a complex mixture, mass spectrometry combined with separation methods is an excellent analytical tool used specifically in the field of: / proteomics.
14) In regard to the expression of enzyme activity, a katal is:
. / a unit that describes the amount of enzyme that will catalyze a mole of substrate in 1 second.
15) When a coenzyme binds to an enzyme, the enzyme portion of the resulting molecule is referred to as the: / holoenzyme.
16) What is a correct statement describing a property of an enzyme? / Enzymes are protein catalysts that decrease the activation energy of a chemical reaction.
17) Statin drugs lower cholesterol by competitive inhibition of the cholesterol-synthesizing enzyme HMG-CoA reductase. A competitive inhibitor binds: / to the active center of the enzyme, thereby causing the Km to increase.
18) How does pH alter an enzymatic reaction rate? / By affecting key amino acids in the enzyme protein at the active center and other sites
19) Regarding enzyme kinetics, the substrate concentration at which the reaction velocity is equal to 0.5 Vmax is referred to as: / Km
20) Zero-order kinetics occurs during the beginning of an enzyme-catalyzed reaction when a substrate concentration is high and the rate of the reaction is _____ on the _____ concentration. / independent; substrate
21) True isoenzymes, which are multiple forms of an enzyme that possesses the ability to catalyze an enzyme’s characteristic reaction, are formed by: / the existence of more than one gene locus coding for the structure of the enzyme protein.
22) During embryonic and fetal development, changes in isoenzyme distribution patterns are common. These changes are thought to result from: / differential expression and changes in the relative activities of gene loci within developing cells.
23) Regarding enzyme kinetics, the Michaelis-Menten plot of the relationship between reaction velocity and substrate concentration is correctly expressed as what formulae? / í = Vmax[S]/Km + [S]
24) Activators increase the rates of enzyme-catalyzed reactions. In some cases, these activators interact with the nonenzymatic component of the reaction such as the substrate. However, in most cases the activator: / binds to the enzyme similar to the enzyme/substrate combination.
25) In a continuous-monitoring assessment of an enzyme reaction rate, what is the preferable measurement? / Measurement of the increasing concentration of product
26) When determining the activity of an enzyme in serum as in a bisubstrate reaction, measurement of two different substances can be made. One measurement determines the decrease in substrate concentration acted upon by the enzyme and the other:. / measures the increase in the concentration of the second product formed.
27) In the reciprocal plot pictured below, the solid line indicates a normal enzyme reaction with no inhibition, and the dotted line indicates a decrease in Vmax and no change in Km. This plot is an example of which type of inhibition? / Noncompetitive
28) The reciprocal plot pictured below indicates a decrease in Vmax and a decrease in Km. The solid line indicates a normal enzymatic reaction. What type of enzymatic inhibition is this? / Uncompetitive
29) Regarding measurement of a property related to substrate concentration such as fluorescence production, the assay that, although more technically demanding, theoretically provides the most accurate measurement of enzyme activity is the: / two-point kinetic method.
30) An example of a posttranslational modification of an enzyme that produces an enzyme isoform would be: / alteration of carbohydrate side chains.
31) Immobilized enzymes are used analytically in various electrochemical techniques. The use of an ion-selective electrode that is coated with an enzyme that produces ions when placed in a substrate solution is a type of: / potentiometric measurement.
32) Any condition, such as extreme temperature or extremes of pH, which changes the shape of the enzyme protein structure generally causes loss of enzymatic activity. This is referred to as: / denaturation.
33) In regard to factors that govern the rate of an enzymatic reaction, first-order reaction kinetics occur at that part of the reaction during which the rate of the reaction is: / directly proportional to the substrate concentration.
34) The use of several enzymatic reactions linked together to provide a means of measuring the activity of the first enzyme or the concentration of the initial substrate is referred to as a(n): / consecutive enzymatic reaction.
35) The interaction of the amino acid side chains with the arrangement of the alpha-helices and beta-sheets to form a three-dimensional protein structure is called the _____ structure of the protein. / tertiary
36) All enzymes are classified to one of six classes based on the reaction they catalyze. Based on this classification, creatine kinase is a member of what enzyme classes? / Transferase
37) Varying different factors and studying their effects on an enzymatic reaction rate in the assessment of most favorable reaction conditions for an enzyme assay is referred to as: / optimization.
38) In this heterogeneous assay, one of the reaction components is attached to the surface of a solid phase. An aliquot of patient sample containing the analyte of interest is added, a wash step occurs, and an enzyme-labeled antibody different from the bound antibody is added followed by the substrate. This type of assay is called: / enzyme-linked immunosorbent assay (ELISA).
39) The substance that is typically injected into an animal to elicit an immune response and induce formation of an antibody is the: / immunogen.
40) A homogeneous fluorescence immunoassay that involves the speed of the rotation of molecules, which is then related to analyte concentration in a patient sample, is known as: / fluorescence polarization immunoassay.
41) Which immunoassay uses a label that was susceptible to making serum cause a false positive because of background fluorescence? / Fluorescent
42) What is considered a quantitative immunoassay? / Electroimmunoassay
43) In the majority of clinical chemistry immunoassays, the analyte of interest in a patient’s serum is typically the: / antigen.
44) Certain immunoassays require separation of bound reactant from free-labeled reactant for determination of analyte concentration. What immunoassays requires this separation step? / ELISA
45) In an enzyme immunoassay with an enzyme-labeled antigen, if there is a high concentration of patient antigen, will there be _____ enzyme available to bind substrate. / more
46) A substance that cannot elicit an immune response alone but that must be conjugated to a carrier molecule to cause antibody production is referred to as a(n): / hapten.
47) An antibody that has very strong affinity to a single antigenic epitope is referred to as a(n) _____ antibody. / monoclonal
48) What information does crossed immunoelectrophoresis provide that basic immunofixation does not? / It provides better resolution of closely related proteins.
49) In an ELISA procedure, the higher the concentration of patient analyte in the test system, the _____ the amount of product formation. / greater
50) The component of an immunoglobulin molecule that determines the antigenic specificity of that antibody is the: / sequence at the amino terminal end of the heavy and light chains.
51) An immunoassay contains an antidigoxin antibody, a digoxin-enzyme conjugate, a substrate, and the sample containing an unknown concentration of digoxin. These components are used in what immunoassays? / EMIT
52) What methods is not a quantitative immunoassay method? / Counter immunoelectrophoresis (CIE)
53) In a precipitin reaction, an excess of antigen over an antibody will lead to: / all antibody sites bound by antigen with no formation of precipitate.
54) You wish to determine which cells contain the protein Substance P in the skin surrounding a flesh wound. Skin scrapings are obtained, fixed in formalin, and mounted on slides. You have an anti-Substance P antiserum. What immunochemical protocol would be most appropriate to use for this experiment? / Immunocytochemistry
55) In a noncompetitive immunoassay reaction format: / antigen from an unknown sample is allowed to react with a solid-phase antibody, and a second labeled antibody is added that reacts with bound antigen.
56) In a noncompetitive immunoassay reaction format, a very high concentration of analyte antigen in the unknown sample might produce a falsely: / decreased result because the high concentration of antigen binds both the capture and labeled antibody, reducing the number of complexes formed.
57) The light-scattering immunochemical method that is considered to have the best sensitivity and a lower detection limit for serum proteins is: / nephelometry.
58) The most commonly used method of reducing carryover in most automated analytical systems is to use: / extensive system flushing between specimens and sample probe washing.
59) Your laboratory has purchased a discrete processing analyzer that is dedicated to performing only thyroid hormone analysis. Which type of pipetting system will likely be in place in this instrument? / Positive liquid displacement fixed-volume
60) An ion-selective electrode system for electrolyte analysis that uses a peristaltic pump to move liquid reagents and samples through a system of tubing is called a _____ analyzer. / continuous flow
61) The most significant improvement in the quality of laboratory test results can be attributed to the ability of automation to: / reduce error and variability caused by manual manipulation.
62) In a chemiluminescent analyzer system: / the excitation event that produces light is caused by a chemical reaction.
63) What component causes carryover of the analyte in a discrete analytical system that uses disposable reaction vessels and measuring cuvets? / The pipetting system
64) A tray of clear sample cups sits on a laboratory bench top for an extended period of time. What analytes might be affected? / Bilirubin
65) The type of automated analyzer in which the operator is able to use in-house reagents or reagents purchased from suppliers different from the analyzer's manufacturer is referred to as a(n): / open analyzer system.
66) In an automated laboratory workstation with a bidirectional laboratory information system interface, the laboratory’s bar-coded label on an individual specimen contains information regarding identification and the laboratory tests requesteD. The processor reads the bar code and the analyzer performs the analyses. Where can a preanalytical error still occur in this automated system? / When a data entry person enters incorrect laboratory test requests
67) Using whole blood as the specimen of choice in an automated analytical system: / essentially eliminates specimen preparation time.
68) The steps involved in the completion of an automated analytical process are collectively referred to as: / unit operations.