Enzyme STAAR Review

For an enzyme to be able to catalyze a reaction, the active site must -

• be occupied by an inhibitor

• increase the activation level

• have a complementary shape to the substrate

• cause the enzyme to be destroyed in the reaction

Enzymes are proteins that have a three-dimensional shape that is specific to a particular substrate. Environmental conditions can change the shape of the protein.

What is the most likely result if the shape of the enzyme changes?

• The substrate will change its shape to match the enzyme.

• The enzyme will no longer be able to catalyze the reaction with the substrate.

• The products made from the enzyme and the substrate will be changed.

• The enzyme will be able to bind to more diverse substrates the before.

People who have Alzheimer's disease experience an increasing loss of brain function and cognition over time. Alzheimer's is characterized by a buildup of abnormal protein fragments that damage brain cells. Recently scientists have discovered an enzyme, BACE2, that decreases these abnormal protein fragments in the brain of a person with Alzheimer's disease. Which statement explains how BACE2 most likely works?

• BACE2 breaks down into smaller pieces that react with the abnormal protein fragments, forming more complex molecules.

• BACE2 speeds up the reaction that breaks down the abnormal protein fragments.

• BACE2 molecules link several abnormal protein fragments together, forming a complete protein.

• BACE2 is a reactant that combines with the abnormal protein fragments.

The diagram represents one way an enzyme can be inhibited.

Which statement explains the effect of an inhibitor on an enzyme?

• A substrate will be able to bond with the enzyme.

• The enzyme will likely be attacked by immune cells.

• The enzyme will be unable to produce more enzymes.

• A substrate will not be able to attach to the enzyme.

Enzymes are proteins that help increase the rate of chemical reactions inside cells. These proteins are composed of many simpler molecules called amino acids. Which of the following suggests that the shape of an enzyme determines the enzyme's function?

• Enzymes are specific to a substrate.

• Enzymes can operate in a wide range of conditions.

• Enzymes are activated by neighboring molecules.

• Enzymes can be found in all life-forms.

Fireflies emit light. The production of light by an organism is called bioluminescence. To generate visible light, cells in a firefly's tail produce thousands of luciferase enzymes. Luciferase binds to a chemical called luciferin. Once bound, the luciferase enzyme speeds up a chemical reaction that combines an oxygen molecule and luciferin to produce oxyluciferin. The reaction requires energy and releases light. Which of the following best describes how the luciferase enzyme speeds up the chemical reaction?

• Luciferase increases the amount of time the light is visible.

• Luciferase descreases the amount of energy required for the reaction to start.

• Luciferase increases the number of sites on luciferin that must bind to oxygen.

• Luciferase decreases the temperature of the environment inside the body of the firefly.