Question

1.When the substrates bind to the active of an enzyme, the active site changes shape. This is an example of: a) lock & key model; b) inhibitor model; c) allosteric model; d) induced fit model; e) none.

2. The change in free energy at equilibrium is: a) increased; b) decreased; c) no net change

3. You have a gram of each of the following: bacon grease, lean ground turkey and bread. Which on has more potential energy and why? a) bacon/fewer bonds; b) turkey/more bonds; c) bread/less bonds; d) grease/more bonds; e) turkey/less bonds; ab) bread/more bonds; ac) all of these are equal; ad) none of them

Answer 1

1) The correct answer is (d) Induced Fit Model

Reason :

When active site changes its shape, then induced fit model comes into play. In other models, the shape of substrate and active site of enzyme remains fixed. The change in shape of active site of enzyme ensures that the substrate fits perfectly and optimally. Here, the shape of active site of enzyme is not exactly complementary to the substrate. Only in presence of substrate, the active site of the enzyme changes its conformation. Hence induced fit model will be applicable here.

2) The correct answer is (c) No net change

Reason :

ΔG is the change in gibbs free energy.  

When  ΔG is zero, then the reaction reaches to equilibrium.  ΔG tells about the energy difference between products and reactants, and basically denotes the thermodynamic potential of the reaction. If  ΔG is zero, then it means no more work can be done, therefore making the rate of forward reaction equal to the rate of backward reaction. Therefore change in free energy ( ΔG) at equilibrium is zero.

3) The correct answer is (d)Grease/more bonds

Reason: Out of the enlisted options, grease contains highest effective number of bonds. Upon breaking of these bonds, highest amount of potential energy will be released. Other options have comparitively lesser number of bonds, so their potential energy will be lower. Hence Grease is the correct answer.

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