Enzyme Technology Multiple Choice Questions on “Factors Controlling in Assays”.
1. The lab methods for measuring enzymatic activity for the study of enzyme kinetic and enzyme inhibition is referred to as _________
A. enzyme reactors
B. entrapment
C. biosensors
D. enzyme assay
Answer: D
Clarification: The lab methods for measuring enzymatic activity for the study of enzyme kinetic and enzyme inhibition is referred to as enzyme assay. A vessel or series of vessels which is used to perform desired conversion by enzymic means is referred to as enzyme reactors. Entrapment is an immobilization method which entraps enzyme in a confined space. Biosensors are analytical devices which converts a biological response into an electrical signal.
2. ____________ is a measure of the quantity of active enzyme present which depends on condition.
A. Km
B. Vmax
C. Enzyme activity
D. Turn over number
Answer: C
Clarification: Enzyme activity is a measure of the quantity of active enzyme present which depends on condition. The amount of enzyme can be either expressed as molar amounts or measured in terms of activity in enzyme units.
Enzyme activity = mole of substrate converted per unit time = rate * reaction volume.
3. SI unit of enzyme activity is _________
A. mol
B. m/s
C. katal
D. Newton
Answer: C
Clarification: SI unit of enzyme activity is katal. 1 katal = 1 mol S-1. Mol represents concentration of any substance. SI unit of velocity is m/s. Newton is the SI unit of force.
4. 1 U = _______ nanokatals.
A. 16.67
B. 3.14
C. 9.8
D. 273
Answer: A
Clarification: Enzyme activity is also represented in terms of U. 1 U = 1µmol/min. 1 U correspond to 16.67 nanokatals. π=3.14. Acceleration due to gravity is given as 9.8 m/s. 1 degree centigrade corresponds to 273-degree kelvin.
5. Enzyme can tolerate extreme high salt concentration.
A. True
B. False
Answer: B
Clarification: Enzymes cannot tolerate high salt concentration as the ions interfere with weak ionic bonds of protein and causes denaturation. This in turn affects enzyme activity. The enzyme is active at salt concentration 1-500 mM. Hence the above statement is false.
6. Which of these factors is not true for enzymes while controlling assays?
A. Extreme high salt concentration cannot be tolerated
B. pH (6-8) is suitable for maximum activity
C. Decrease in temperature leads to decreased reaction rates
D. Increase in substrate concentration leads to increase in rate of reaction
Answer: C
Clarification: “Decrease in temperature leads to decreased reaction rates.” This is not true. All enzyme work within a specific range of temperature which is suitable to the organisms. Increase in temperature leads to increase in reaction with a limitation that, at higher temperature, there might be decrease in reaction rates.
7. Which of these factors is true for enzymes while controlling assays?
A. Extreme high salt concentration can be tolerated
B. pH (6-8) is suitable for maximum activity
C. Decrease in temperature leads to decreased reaction rates
D. Decrease in substrate concentration leads to increase in rate of reaction
Answer: B
Clarification: “pH (6-8) is suitable for maximum activity”. This statement is true. Most enzymes are sensitive to pH and have specific range activity of 6-8. Enzyme activity can be stopped due changes in pH which leads denaturation of 3-dimensional structure of enzyme by breaking the ionic and hydrogen bonds present in it.
8. Which of these factors is true for enzymes while controlling assays?
A. Extreme high salt concentration can be tolerated
B. pH (2-4) is suitable for maximum activity
C. Macromolecular crowding does not alter the rates of the reaction
D. Increase in substrate concentration leads to increase in the rate of reaction
Answer: D
Clarification: “Increase in substrate concentration leads to an increase in the rate of reaction”. This statement is true. However, the enzyme may become saturated and act as limiting factor reaction rates. This may happen because of the occupancy of the active sites in the enzymes most of the time.
9. Macromolecular crowding does alter the rate and equilibrium constant of enzyme reaction.
A. True
B. False
Answer: A
Clarification: Macromolecular crowding occurs because of the large amount of macromolecule in solution. The large amounts lead to cellular destruction by a natural process which is accompanied by changes in enzymes and breakdown of cofactors. This leads to the death of the organisms, in turn affecting the rate and equilibrium constant of enzyme reaction.