Unit 3 AP Biology (Cellular Energetics)

Front

Which macromolecules are enzymes?

Back

Protein

Answer explanation

Enzymes are a macromolecule made up of amino acids. Recall, the proteins are those macromolecules. All enzymes are proteins but not all proteins are enzymes.

Front

Why does substrate binding activate the enzyme?

Back

Changes shape

Answer explanation

When anything binds to a protein, it undergoes the induced fit model. This involves the protein undergoing a conformational shape change which can allow the active site to be more accessible (thus activating the enzyme)When anything binds to a protein, it undergoes the induced fit model. This involves the protein undergoing a conformational shape change which can allow the active site to be more accessible (thus activating the enzyme)

Front

How does an enzyme speed up a chemical reaction?

Back

Decrease the activation energy required

Answer explanation

By decreasing the activation energy, it makes the reaction more favorable. The reaction can reach the intermediate phase sooner which will increase the reaction rate (aka speed up the chemical reaction)

Front

Where does the substrate bind on an enzyme?

Back

Active site

Answer explanation

The active site is the location on the enzyme where the substrate binds. Once this binds, it is called the substrate/enzyme complex.

Front

How does an enzyme affect activation energy?

Back

Decrease

Answer explanation

Enzymes will decrease the activation energy of a reaction by orienting the reactants or straining the bonds.

Front

What effect does an enzyme have on the reaction rate?

Back

Increase

Answer explanation

Due to the decrease activation energy, the reaction can proceed more frequently as it reaches the intermediate state sooner. If it can react more frequently, this is the definition of an increase in reaction rates.

Front

How does the enzyme affect the change in Gibbs free energy?

Back

Stays the Same

Answer explanation

See the ΔG is the same with and without the enzyme.

See the activation energy is less with an enzyme.

Front

What happens to an enzyme if the temperature decreases too low?

Back

Enzyme decreases rate

Answer explanation

Enzymes are proteins. The bonds will not break if the temperature decreases. This decrease in temperature will affect the kinetic energy of the system which will decrease the reaction rate as the collisions would have decreased energy nor collide as often.

Front

If the enzyme is denatured, what happens to the reaction rate?

Back

Reaction rate decreases

Answer explanation

Enzymes increase the reaction rate, but do not affect the Gibbs free energy. This means that the reaction will take place with or without the enzyme present.

If the enzyme is absent/denatures the reaction will still take place, just slower.

Front

Are enzymes consumed by the reaction and must be re-added?

Back

False

Answer explanation

Enzymes are the worker horses of the cell. After they participate in the reaction, their structure returns back which allows for another substrate to bind for another reaction.