3. Energy & Cell Processes

How do enzymes lower activation energy?

A plot of reaction rate (velocity) against temperature for an enzyme indicates little activity at 10°C and 45°C, with peak activity at 35°C. The most reasonable explanation for the low velocity at 10°C is that __________.

What is a transition state? a. the shape adopted by an enzyme that has an inhibitory molecule bound at its active site b. the amount of kinetic energy required for a reaction to proceed c. the intermediate complex formed as covalent bonds in the reactants are being broken and re-formed during a reaction d. the enzyme shape after binding an allosteric regulatory molecule

What would happen if activation energy barriers didn't exist? a. Substrates would not bind properly to enzymes; b. Chemical reactions in the body would never occur; c. Enzyme function would not be affected; d, Metabolic reactions would proceed even if their products were not needed.

If an enzyme is added to a solution where its substrate and product are in equilibrium, what will occur? a. Additional substrate will be formed. b. The reaction will change from endergonic to exergonic. c. The free energy of the system will change. d. Nothing; the reaction will stay at equilibrium.

If you were to expose glucose to oxygen on your lab bench, why would you not expect to see it burn as described by the reaction in Figure 8.6? a. The reaction is endergonic and requires an input of energy. b.The reaction is not spontaneous unless an enzyme is added. c. The sugar must first be phosphorylated to increase its potential energy. d. Activation energy is required for the sugar and oxygen to reach their transition state.

In the context of cell communication, what is the primary role of activated protein kinases?