Lecture 3 and 4 Flashcards by Katlyn Heneghan

To measure analyte levels, laboratory assays most commonly use ____

serum

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___:the watery acellular portion of blood separated by centrifugation of whole blood in the presence of anticoagulant

Plasma

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True or False: plasma is a non-physiologic solution while serum is a physiological solution

False
plasma = physiological
serum = non-physiological

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What is a major advantage of serum?

There are NO additives required to prevent clotting

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True or False: plasma contains plasminogen while serum does not

True

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True or False: Most diagnostically important enzymes have intracellular functions and do not normally function in blood

True

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What are two reasons that a healthy person may have enzymes in their blood?

Active secretion (i.e., coagulation precursors such as prothrombin)
Release from cells at LOW LEVELS during normal cell turnover.

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Elevated blood enzyme concentrations result when
____are damaged and intracellular enzymes are released into the blood

cell membranes

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Detection of elevated enzyme levels can help to:
1)
2)
3)

Make or confirm a diagnosis.
Develop a prognosis.
Monitor response to a drug therapy

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Two clinical reasons for elevated enzymes?

1) Normal cell turnover
2) Pathologies

-Cellular damage, disrupts cell membranes (hepatitis, MI)
-Enzyme induction (response to metabolism of drugs)
-Physical obstructions (i.e., tumors, stones)
-Cell proliferation

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Creatine kinase (CK or CPK) is found in the ___ and ___

Lactate dehydrogenase (LDH or LD) is found in ____, ___, ___, and ___

muscle and brain

liver hepatocytes, muscle, RBCs, brain

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True or False: Both ALT/AST are found in liver hepatocytes. However, AST is also found in muscle.

True

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ALK or ALP is found in the ___ and bone

Gamma glutamyltransferase GGT or GGTP is found in ___ and ___

Liver (hepatobiliary) and bone

Liver (biliary tree), pancreas

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Which of these enzymes is the most specific test?

Which of these enzymes is the least specific test?

Most specific = ALT
Least specific = LDH

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How might you improve diagnostic specificity?

Panels/profiles; isoforms

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What is found in BMP?

hint: SPOON CCCG

sodium
potassium
CO2
BUN
creatine
chloride
calcium
glucose

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Which panel is best for identifying acute problems involving kidney, diabetic shock, respiratory
distress and congestive heart failure?
A. CMP
B. BMP
C. LDH

B. BMP

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Which panel is also known as Chem 7? Which panels is also known as Chem 12?

BMP (Chem 7); CMP (Chem 12)

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Which panel is common for
during physical exam or to monitor chronic conditions such as HTN, DM, or monitor response to a drug regimen
that may have kidney- or liver-related adverse reactions

CMP

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In addition to the tests in the BMP, CMP’s look at what other 6 substances?

-Albumin
-ALK/ALP
-AST
-ALT
-Total Bilirubin
-Total Protein

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Renal profile (4) ?

Blood urea nitrogen (BUN)
Creatinine
BUN/Creatinine ratio
Uric Acid

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Liver profile?

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Muscle profile?

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The Comprehensive Metabolic Panel includes the
Basic Metabolic Panel tests and also assesses which
of the following organs?

A. Heart
B. Pancreas
C. Liver
D. Brain

C. Liver

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Which blood-derived substance does not require the addition of an anticoagulant? A. Plasma B. Serum

B. Serum

___: urea is a waste product of protein digestion; indicates kidney dysfunction ____:waste product of muscle contraction cleared by kidneys; indicates kidney dysfunction.

BUN; Creatine

_____: >10:1 to 20:1 indicates poor blood flow to kidneys (i.e., congestive heart failure)

BUN: Creatinine

____: waste product of purine breakdown cleared by the kidneys; indicates hyperuricemia/gout and kidney disease

Uric Acid

In the liver profile, what three tests assess hepatocellular damage?

ALT: AST: LDH* *=non specific

Which liver profile test is used to assess chronic (decreased value) vs. acute (normal) liver damage?

Albumin

In the liver profile, ___, ___, and ___ are used to assess biliary tract damage - cholestasis

ALP/ALK; GGT; 5 NT

What tests are used to identify heme degradation product diagnostic for liver function, hemolytic anemias?

T, D, and I BIL

___ is expressed in sk. and cardiac muscle and liver

AST

____ is non-specific test for muscle and heart damage

LDH

____is required for muscle cell function; after heart attack, strenuous exercise, muscle injury

What is a good screening test for prostate cancer?

Prostate-specific antigen (PSA)

What 4 tests evaluate pancreatic function?

-Amylase -Lipase -Lipase:Amylase ratio (possible differentiation of alcoholic vs. non-alcoholic acute pancreatitis) -Trypsinogen/Trypsin

Which elevated serum test result paired with elevated AST levels would be the most specific diagnostic for liver disease? A. LDH B. ALT C. ALK D. BUN

B. ALT

Which analyte is most likely to be elevated in a patient’s serum following a heart attack? A. CK B. BUN C. Creatinine D. Amylase

A. CK

Elevated CK following a heart attack will most likely accompany elevated... A. Albumin B. BUN C. AST D. Lipase

C. AST

____: the ability of test to actually measure what it claims to measure ___: the ability to reproducibly obtain the same result on the same patient sample.

Accuracy Precision

The reference range is the range of values within __ SD of the mean, which covers __% of healthy individuals

2; 95%

All isozymes of an enzyme catalyze the same reaction but differ slightly in what three ways?

1) Amino acid composition (often different related gene products) 2) Cell- and tissue-type in which they function 3) Timing of expression

Which isozyme is a tetramer composed of various combinations of H-subunits (Heart) and M-subunits (muscle)?

LDH Isoenzymes

If LDH-1:LDH-2 >1, what does this indicate? If LDH-5:LDH-4 > 1, what does this indicate?

HEART damage LIVER damage

Where is LDH-1 predominately found? Where is LDH-5 predominately found?

LDH-1: Heart LDH-5: Liver

Which isoezyme is dimer composed of 2 B-monomers (Brain), 2 M-monomers (muscle) OR one of each?

CK-1, found in the brain, can help diagnose ____

CNS damage

Found in the myocardium, CK-2 can help diagnose ___

an acute MI

Located predominately in the skeletal muscle, CK-3 can help diagnose ____

skeletal muscle damage

Combination of ___and LDH-1 isozymes, along with ____ and ____ are diagnostic for AMI (acute MI)

CK-MB ; Troponins ; Myoglobin

True or False: There is a Troponin I, T, and C

True

While TnI, TnT, and CK-MB become elevated within 3 to 12 hours, TnI and TnT take ~5-14 days to return to normal range while CK-MB takes ___ days

2-3 days

Which LDH isozyme is the most specific diagnostic test for liver damage? A. LDH-1 B. LDH-2 C. LDH-3 D. LDH-4 E. LDH-5

E. LDH-5

Which specific diagnostic test for AMI would be least sensitive for diagnosis after 2 days post-MI? A. LDH-1 B. CK-MB C. Troponins

B. CK-MB

____forms upon binding of substrate to the enzyme and leads to a conformation change

Enzyme-substrate (ES) complex

True or False: Enzymes have catalytic efficiency and specificity

True

____: non-protein molecules that enhance enzyme activity

Co-factors/co-enzymes

Zinc is an example of a ___ while NAD is an example of a ___

Co-factor, Co-enzyme

____: an active enzyme associated with its non-protein component ____: inactive enzyme without its non-protein component

Holoenzyme; Apoenzyme

True or False: enzymes provide a more energetically favorable path from reactants to products by lowering the activation energy barrier

True

The higher the energy barrier, the ____ the reaction

slower

Another name for the activation energy barrier is ____

free energy of activation

___: energy difference between reactants and transition state

Free energy of activation

_____: high-energy intermediate formed prior to product formation

Transition state (T*)

True or False: Enzymes ↓ free energy of activation required to reach T*

True

A reaction occurs if molecules contain enough energy to overcome the energy barrier to achieve __

_____ is determined by # of molecules that have sufficient energy to overcome the barrier

Reaction rate or velocity

True or False: If free energy of activation is low: more molecules have sufficient energy to reach T* AND reaction proceeds more rapidly

True

The active site contains ____ groups, which contain amino acid residues that _____ protons

catalytic donates/accepts

True or False: hydrogen bonding promotes T state formation

True

Factors influencing enzymatic reaction velocity?

-**substrate concentration [S] -Temperature -pH

With constant [E], reaction rate increases with ↑[S] until reaching ___

Vmax (maximum velocity)

True or False: nce Vmax reached, reaction rate does increase with addition of more substrate

False - NOT

What type of curve do allosteric enzymes show?

Sigmoidal

There is a ____ curve for most enzymatic reactions

Hyperbolic

MM assumptions?

* [S] >> [E] * rate of ES formation = rate of ES breakdown

Km = ___ at ½ Vmax

[S]

Small Km means ___ [S] needed to reach Vmax

Low

What type of inhibitor covalent binds to enzyme, prevents enzyme from interacting with substrate, and leads to “loss” of enzyme activity (i.e., lead poisoning)?

Irreversible inhibitor

____: noncovalent binding with enzyme

Reversible Inhibitor

True or False: There are competitive and non-competitive irreversible inhibitors

False

What type of inhibitors compete with S to bind enzyme’s active site?

Competitive (reversible) Inhibitors

What effect does a competitive inhibitor have on Vmax and Km?

Statin (Pravastin) drugs inhibit rate-limiting step in cholesterol biosynthesis and are an example of what type of inhibitor?

Competitive Inhibitor

What drug competes with substrate HMG-CoA for binding to HMG CoA-reductase?

Pravastin (competitive inhibitor)

____: bind to different site than the substrate and prevent reaction from occurring – does NOT compete with S for binding.

Non-competitive Inhibitors

What two places can non-competitive inhibitors bind to?

Can bind to either: 1. free enzyme 2. ES complex

Penicillin, Amoxicillin inhibit bacterial cell wall synthesis and are irreversible/reversible?

Irreversible

True or False: ACE inhibitors are reversible competitive inhibitors

True

True or False: COX inhibitors are competitive inhibitors

Tru

Aspirin is a ____inhibitor while Advil/Motron are ___, ___ inhibitor

irreversible ; reversible competitive

What type of enzymes frequently catalyze the committed, rate-limiting step in a pathway?

Allosteric Enzymes

What type of molecules regulate allosteric enzymes?

Effector molecules (bind non-cov at site other than active)

____ effector: reduce or inhibit enzyme activity ____ effector: stimulates or increase enzyme activity

Negative Positive

True or False: Effectors can modify Vmax only

False - Vmax, K 0.5 or both

Homotropic effectors are usually ___ effectors

positive

Binding of substrate at allosteric site enhances activity at substrate- binding site = ____

cooperativity

Why do allosteric effectors show sigmoidal curve?

Sigmoidal curve because higher [S] initially needed for reaction to proceed

True or False: For a homotropic effector, the substrate = effector, but this is not the case with heterotropic effectors.

True

An example of covalent modifications is phosphorylation of specific ___, ___, or __residues:

Ser, Thr, Tyr

True or False: Phosphorylation may activate or inhibit its target enzyme

True

True or False: allosteric and covalent modifications are more rapid (seconds to minutes)

True

In the case of enzyme inhibition by a competitive inhibitor, the Km will...? A. Increase B. Decrease C. Not change

A. Increase

In the case of enzyme inhibition by a non-competitive inhibitor, the Vmax will...? A. Increase B. Decrease C. Not change

B. Decrease

Which of the following is most likely to decrease the velocity of an enzymatic reaction? A. Moderate rise in temperature B. Increase in [S] C. Binding of a positive homotropic effector D. Extremely high or low pH

D. Extremely high or low pH

Which of the following directly interferes with binding of a substrate to an enzyme’s active site? A. A non-competitive inhibitor B. Binding of a heterotropic allosteric effector C. A competitive inhibitor

C. A competitive inhibitor

Which of the following is defined by the x-intercept in a Lineweaver-Burke plot for an enzyme? A. 1/Vmax B. vo C. -1/Km D. [S]

C. -1/Km