Clinical Chemistry Exam 1 Lecture 6 – Flashcards
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| True or False: Enzymes are found in All body tissues |
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| True |
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| Many enzymes are present in ___ from normal cellular turnover |
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| Plasma |
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| Enzymes are ____ ____ and _____, not altered or consumed during the reaction |
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| Biologic proteins Catalysts |
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| _____ amounts of Enzyme are released following cellular damage |
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| Increased |
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| Basic Enzyme Reaction |
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| E + S ES E + P |
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| Substrate Concentration is what order kinetics? |
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| First |
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| First Order Kinetics is directly proportional to what? |
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| Substrate concentration |
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| In First Order Kinetics, what is provided in excess? |
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| Enzyme |
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| At some point in First Order Kinetics, substrate will be consumed and ____ ____ is reached |
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| Maximum Velocity |
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| Michaelis-Menton Constant (Km) |
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| Mathematical expression of the relationship between velocity and substrate |
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| M-Mm Constant (Km) = |
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| Substrate concentration at which the enzyme yields half the possible maximum velocity |
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| Which two types of plots provide visualization of first order kinetics? |
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| M-M and Lineweaver-Burk |
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| Enzyme Concentration is what order Kinetics? |
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| Zero |
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| What is in excess during Zero Order Kinetics? |
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| Substrate |
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| True or False: With Zero Order Kinetics, the Reaction rate depends on enzyme concentration |
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| True |
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| With Zero Order Kinetics what is supplied by the patient? |
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| Enzyme |
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| With Zero Order Kinetics what is supplied by manufactured reagent? |
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| Substrate |
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| Why is it called Zero Order Kinetics? |
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| When the rate of velocity no longer increase, velocity rates level off, signalling "zero" amount of increase in rate |
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| pH |
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| Extremes will denature or change ionic state of enzymes |
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| Most enzymes function at what pH? |
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| 7-8 |
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| pH is controlled in labs by what? |
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| Buffer solutions |
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| Increasing the temperature increases the ____ ____ to a point |
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| Reaction Rate |
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| For every ___ degree rise, the rate doubles until the enzyme is denatured |
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| 10 |
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| At what temperature will the enzyme usually denature? |
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| >40 degrees Celsius |
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| Most assays are run at what temperatures? |
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| 25, 30, 37 degrees Celsius |
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| True or False: Avoid repeated freeze-thaw |
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| True |
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| If testing is delayed what should you do with the sample to preserve the enzyme levels? |
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| Freeze or Refrigerate |
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| True or False: It takes a few minutes for ALL enzymes to combine with substrate |
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| True |
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| The reaction time is what phase of the reaction? |
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| Linear |
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| About ______ or more minutes into testing, the reaction rate begins to diminish |
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| 6 |
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| Measurements should be taken during what phase of the reaction? |
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| Linear |
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| Cofactors |
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| Nonprotein molecules that may be necessary for proper enzyme function |
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| Cofactor Activators |
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| Inorganic molecules |
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| Name 3 Cofactor Activators |
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| Calcium Magnesium Other Metallic ions |
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| Cofactor Coenzymes |
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| Organic Molecules Often provided in the testing reagent |
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| Name 2 Cofactor Coenzymes |
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| NAD Vitamin B family |
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| What is the following an example of? Creatine + ATP --(CK / Mg)--> Creatine Phosphate + ADP |
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| Activators |
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| What is the following an example of? Pyruvate + NADH --(LD)--> Lactate + NAD |
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| Coenzymes |
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| What are 7 Factors that influence Enzyme Reactions? |
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| Substrate Concentration Enzyme Concentration pH Temperature Reaction Time Cofactors Inhibitors |
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| Competitive Inhibitors |
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| Bind to the active site of an enzyme |
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| What do you add to overcome Competitive Inhibitors? |
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| Substrate |
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| Is Competitive Inhibitors possible to anticipate? |
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| No |
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| Noncompetitive Inhibitors |
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| Bind to enzyme at a place other than the active site Causes structural changes to the enzyme |
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| True or False: Adding more substrate may not help with noncompetitive inhibitors |
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| True |
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| True or False: The results of Noncompetitive inhibitors may be irreversible |
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| True |
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| Assays measure enzyme _____ which is a reflection of concentration |
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| activity |
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| What can be used to measure enzyme activity? |
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| Increase in product Decrease in substrate Decrease in coenzyme Increase of an altered coenzyme |
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| In what Order are Measurements of Enzyme Activity always performed? |
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| Zero |
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| What must be in excess when measuring enzyme activity? |
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| Coenzyme |
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| Fixed-Time Method (End Point) |
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| The reaction proceeds for a designated time and is then stopped |
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| The velocity of a Fixed-Time Method is assumed to be what? |
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| Linear and proportional to enzyme concentration |
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| Continuous-Monitoring Method (Kinetic Analysis) |
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| Multiple measurements of absorbance are made every 30-60 seconds OR continuously |
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| True or False: Continuous-Monitoring Method - Linearity may be more adequately verified |
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| True |
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| A sudden _____ in the reaction rate can be readily observed in the Continuous-Monitoring Method |
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| Decrease |
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| If a change in Absorption is not constant, then an ____ _____ is present |
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| Unknown Variable |
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| If the change in Absorption is not constant it may result from what? |
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| high levels of patient enzymes rapidly depleting the substrate |
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| What should you do if the change is absorption is not constant? |
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| Dilute patient sample and re-run |
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| International Unit (U or IU) |
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| The amount of enzyme that will catalyze the reaction of 1 micromole of substrate per minute under specified conditions of temperature, pH, substrates, and activators |
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| The International Unit is in what concentration? |
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| Units per Liter (U/L or IU/L) |
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| If an enzyme assay is 150 IU/L at 25C, what will be the product concentration if the assay is run at 35C? |
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| 300 IU/L |
