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CLINICAL CHEM > Enzymes > Flashcards

Enzymes Flashcards

(72 cards)

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1
Q

T or F: All enzymes are proteins but not all proteins are enzymes

A

T

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2
Q

how do enzymes speed up a rxn

A

they lower the activation energy

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3
Q

def? non-protein chemical compound that is bound tightly to an enzyme and is required for catalysis.

A

cofactor

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4
Q

are cofactors organic or inorganic

A

inorganic

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5
Q

are coenzymes organic or inorganic

A

organic

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6
Q

what is it called when a coenzyme is bound tightly to an enzyme

A

prothetic group

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7
Q

def? enzyme (apoenzyme) + COEnzyme (prothetic)

A

holoenzyme

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8
Q

t or F: The enzyme shifts the equilibrium of the reaction to the right.

A

F

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9
Q

T or F: The enzyme alters the equilibrium constant of the reaction.

A

F

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10
Q

T or F: The enzyme increases the rate of the reaction.

A

T

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11
Q

T or F: The enzyme alters the energy difference between reactants and products

A

F

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12
Q

if the substrate and inhibitor bind to the same place what kind of inhibition is this

A

competitive

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13
Q

T or F: A competitive inhibitor will alter the apparent Km of the reaction

A

T

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14
Q

T or F: An enzyme alters the Gibb’s free energy of the reaction.

A

F

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15
Q

T or F: Enzymes cause a reaction with a positive free energy to occur spontaneously.

A

F

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16
Q

T or F: An enzyme’s natural substrate has the highest Km.

A

F

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17
Q

what is used to measure enzymatic activity

A

spectrophotometric

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18
Q

what form of NADPH and NADH does UV light get absorbed

A

reduced

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19
Q

if an enzyme rxn does not result in a change in absorbance what can be used

A

coupled assay

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20
Q

an enzyme using NADH as a substrate can be assayed at what nm of light

A

340 nm

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21
Q

I unit of enzyme activity =

A

1 mol of molecules production / min

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22
Q

what is beers law

A

the absorbance of a sample is proportional to the concentration

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23
Q

what is lamberts law

A

the absorbance of a sample is proportional to the sample thickness

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24
Q

what is the formula for absorbance

A

= molar absorptivity x path length x conc

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25
what is the fomula for conc
= (absorption x molar absorptivity x path length) dilution factor
26
what is measured in biological samples for diagnosis, prognosis, assessment of treatment, and monitoring the progression of the disease.
enzymes
27
what is the clinical significance of measuring ALP (alkaline phosphatase)
hepatic disorder
28
what is the clinical significance of measuring CK (creatine kinase) and LD (lactate dehydrogenase)
myocardial infarction
29
what cofactor does CK require
Mg 2+
30
Creatine + ATP =
phosphocreatine
31
where do you mostly find CK
skeletal muscles
32
function of phosphocreatine
energy reservoir
33
what tissue has CK-MM
skeletal
34
what tissue has CK-MB
cardiac
35
what tissue has CK-BB
brain
36
which CK enzyme is the most specific marker of a heart attack
CK-MB
37
what is a sensitive indicator of acute myocardial infarction and muscular dystrophy.
CK
38
what kind of sample is needed for measuring CK
serum or heparinized plasma
39
T or F: it is ok for a CK sample to be collected with EDTA, citrate, or oxalate
F
40
_____ samples should be avoided with testing for CK
hemolyzed
41
what tissues have LD-1
heart and RBC
42
what tissues have LD-2
heart and RBC
43
what tissue has LD-3
lungs
44
what tissues have LD-4 and LD-5
liver and skeletal muscle
45
which LD enzyme is usually the highest
LD-2
46
A physician calls to request a CK on a sample already sent to the laboratory for coagulation studies. The sample is 4-hour-old citrated/EDTA blood and has been stored at 4oC. The plasma shows very slight hemolysis. What is the best course of action and the reason for it?
Reject the sample because the citrate/EDTA will interfere
47
True or false? CK Highest levels are seen in Duchenne’s muscular dystrophy.
T
48
T or F? Ck Levels are unaffected by strenuous exercise
F
49
T or F? CK Levels are unaffected by repeated intramuscular injections
F
50
t or f? The enzyme is highly specific for heart injury (CK)
F
51
t or F? An LD-1:LD-2 ratio greater than 1.0 is specific evidence of AMI.
F
52
t or F? Malignancy usually causes an increase in LD-2, LD-3, LD-4.
F
53
T or F? LD-3 is normally the isoenzyme in highest concentration in serum.
F
54
t or f? Hepatic injury is associated with increases in LD-4 and LD-5.
T
55
what conditions will interfere with the measurement of LD?
Slight hemolysis during sample collection
56
t or f? The formation of pyruvate from lactate (forward reaction) generates NAD1. (when measuring LD)
F
57
t or F? The pyruvate to lactate reaction proceeds at about twice or 3 times the rate as the forward reaction. (when measuring LD)
T
58
t or F? The lactate to pyruvate reaction is optimized at pH 7.4. (when measuring LD)
F
59
T or F: The lactate to pyruvate reaction is optimized at pH 8.4 (when measuring LD)
T
60
t or F: when measuring LD the negative rate reaction is preferred.
F
61
t or f (enzymatic rxn): NADH has absorbance maxima at 340 and 366nm.
T
62
t or f (enzymatic rxn): Enzyme concentration must be in excess to achieve zero-order kinetics.
F
63
t or f (enzymatic rxn): Rate is proportional to substrate concentration in a zero-order reaction.
F
64
t or f (enzymatic rxn): Accumulation of the product increases the reaction rate.
F
65
what is the coupling enzyme used in the kinetic AST reaction of Henry.
Malate dehydrogenase
66
t or f: Hemolysis will cause positive interference in both AST and ALT assays.
T
67
t or f: in the methods of Henry Loss of activity occurs if samples are frozen at -200C.
F
68
t or f: in the method of Henry The absorbance at the start of the reaction should not exceed 1.0 A.
F
69
t or F: in the method of Henry Reaction rates are unaffected by addition of P-5’-P to the substrate.
F
70
T or F: amylase requires Ca2+ for full activity.
T
71
what is the most sensitive marker for alcoholic liver disease.
g-Glutamyltransferase (GGT)
72
what mineral do parathyroid hormone regulate
calcium, phosphorus and magnesium

CLINICAL CHEM (7 decks)

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