Enzymes as catalysts

What are enzymes?

Enzymes are biological catalysts that increase the rate of chemical reactions without being consumed.

What is activation energy?

The minimum amount of energy required to start a chemical reaction.

Do enzymes alter the overall energy change of a reaction?

No. Enzymes do not change the overall energy change; they only lower activation energy.

What is the structure of an enzyme?

Enzymes are globular proteins with a specific region called the active site.

What happens in the induced-fit model?

The active site changes shape to fit the substrate more closely during binding.

What are anabolic and catabolic reactions?

Anabolic reactions build larger molecules; catabolic reactions break molecules down.

Why are enzymes essential for metabolism?

They speed up reactions so metabolic processes occur fast enough to sustain life.

What is the effect of temperature on enzyme activity?

Higher temperatures increase collisions, but extreme heat denatures enzymes.

How does pH affect enzyme activity?

Each enzyme has an optimal pH; deviations alter structure and reduce activity.

What happens to the reaction rate at the saturation point?

The reaction rate plateaus because all active sites are occupied.

What are intracellular and extracellular enzymes?

Intracellular enzymes work inside cells; extracellular enzymes act outside cells.

Give an example of an extracellular enzyme.

Amylase, which breaks down starch in the mouth.

Why are enzyme-catalyzed reactions important for homeostasis?

They support essential processes like digestion, metabolism, and cellular repair.

How do enzymes facilitate DNA replication?

Enzymes such as DNA polymerase ensure accurate copying of genetic material.

What is enzyme specificity?

Each enzyme catalyzes only one type of reaction or acts on a specific substrate.

Why is enzyme specificity important?

It allows precise control of metabolic pathways and prevents harmful side reactions.

What factors can affect enzyme activity?

Temperature, pH, and substrate concentration.

What happens to enzyme activity at extreme temperatures?

Extreme heat denatures enzymes, reducing activity.

What is the relationship between substrate concentration and reaction rate?

Rate increases with substrate concentration until saturation, where it plateaus.

What are the four steps of the induced-fit model?

Substrate approaches → Binding → Catalysis → Release.

How do enzymes increase the rate of reactions?

By lowering the activation energy required.

Give an example of an enzyme and its function.

Catalase breaks down hydrogen peroxide (H₂O₂) into water and oxygen.

Why are enzymes compared to factory workers?

Each enzyme specializes in one reaction, similar to workers with specific tasks.