Enzymes are biocatalysts. They catalyze biochemical reactions. In general, they reduce the activation energy of reactions. Many physicochemical processes are enzyme-mediated. Which of the following reactions is not enzyme-mediated in the biological system?
| 1. | Dissolving CO2 in water |
| 2. | Untwining the two strands of DNA |
| 3. | Hydrolysis of sucrose |
| 4. | Formation of peptide bond |
| A. | Enzyme releases products of the reaction and gets free. |
| B. | Substrate induces the enzyme to alter its shape. |
| C. | The substrate binds with the active site of the enzyme. |
| D. | Enzymes-product complex is formed. |
Which of the following statements regarding enzyme inhibition is correct:
| 1. | Competitive inhibition is seen when a substrate competes with an enzyme for binding to an inhibitor protein |
| 2. | Non-competitive inhibitors often bind to the enzyme irreversibly |
| 3. | Competitive inhibition is seen when the substrate and the inhibitor compete for the active site on the enzyme |
| 4. | Non-competitive inhibition of an enzyme can be overcome by adding large amounts of substrate |
Role of enzyme in reactions is to:
1. Decrease activation energy
2. Increase activation energy
3. Act as an inorganic catalyst
4. None of the above
The figure given below shows the conversions of a substrate into product by an enzyme. In which one of the four options (1-4), the components of the reaction labelled as A, B, C and D are identified correctly:
Options
| A | B | C | D | |
| 1. | Transition state |
Potential energy |
Activation energy without enzyme |
Activation energy with enzyme |
| 2. | Potential energy |
Transition state |
Activation energy with enzyme |
Activation energy without enzyme |
| 3. | Activation energy with enzyme |
Transition state |
Activation energy without enzyme |
Potential energy |
| 4. | Potential energy |
Transition state |
Activation energy without enzyme |
Activation energy with enzyme |