Biochemical pathways, coenzymes, and inhibitors

Which of the following may occur when a molecule binds to a specific site on an enzyme (but not its active site) and this binding produces a change in the enzyme shape that affects and reduces its activity?

• Competitive inhibition

• Substrate concentration

• Competitive regulation

• Non-competitive inhibition

The ATP produced by cellular respiration cannot be stored and, because it is unstable, any excess ATP loses its energy and is wasted. At times of high demand, the rate ATP production is stepped up and at times of lower demand, the rate is slowed.  Which of the following is this an example of?

• Denaturation

• Regulation

• Enzyme concentration

• Non-competitive inhibition

As the temperature increases above the optimum, the reaction rate reduces sharply. This occurs because enzymes are proteins and when temperatures exceed the optimum, (a)   of the protein occurs.

When regulating biochemical pathways, the binding of (a)    to the allosteric site produces a change of shape in an enzyme that stops enzyme activity.

Which of the following is true?

1. As the temperature of an enzyme is decreased, the number of collisions between substrate and enzyme increases.

2. The optimal temperature is the temperature in which an enzyme has the greatest rate of activity.

3. Different enzymes may have a different optimal pH.

• 2 and 3

• 1 and 3

• 2 only

• 1 only

All enzyme molecules are saturated with substrate molecules when the maximum reaction rate of an enzyme is reached.

• True

• False

Inhibitors always bind to the active site.

• True

• False

Reactions are coupled so that the energy _____________ by catabolic reactions can be transferred to drive energy-requiring _____________ pathways.

• Released; catabolic

• Absorbed; catabolic

• Released;

  anabolic

• Absorbed; anabolic

A chemical reaction that is energy requiring is (a)  

A chemical reaction that is energy releasing is (a)