Enzymes Lecture Notes

Flashcards covering key concepts about enzymes, their characteristics, and how they function as biological catalysts.

What are enzymes?

Biological catalysts made of proteins involved in metabolic reactions.

What is a catalyst?

A substance that speeds up the rate of chemical reactions.

What is the definition of a catalyst?

A substance that can speed up a chemical reaction without itself being chemically changed at the end of the reaction.

What is the definition of an enzyme?

Proteins that function as biological catalysts, speeding up the rate of chemical reactions and remaining chemically unchanged at the end.

Give examples of reactions that enzymes catalyse.

Reactions that build up complex substances and reactions that break down complex substances.

Give examples of enzyme-catalysed chemical reactions in living organisms.

Protein synthesis, photosynthesis, digestion, respiration, and decomposition of hydrogen peroxide.

Name the enzyme. Lipid

Lipase

Name the enzyme. Protein

Protease

Name the enzyme. Carbohydrate

Carbohydrase

What are the characteristics of enzymes?

Made of proteins, speed up chemical reactions, specific in action, require small amounts, remain chemically unchanged, affected by temperature and pH.

What hypothesis describes the action of an enzyme on a substance?

Lock and Key hypothesis

Describe the 'lock-and-key' hypothesis of enzyme action.

An enzyme will only act on a specific substance called the substrate. The substrate is the key, and the enzyme is the lock.

What forms the active site on an enzyme molecule?

Depressions on the enzyme molecule.

What happens when a specific substrate binds with an enzyme's active site?

They form the enzyme-substrate complex.

What happens to the enzyme after a chemical reaction occurs on the substrate molecules?

The products formed leave the enzyme’s active site, but the enzyme molecule itself remains chemically unchanged.

What is an enzyme's active site complementary to?

The shape of its substrate.

What is the effect of temperature on enzyme activity?

Enzyme activity is affected by temperature. Activity is fastest at the optimum temperature. High temperatures can denature enzymes.

What happens when an enzyme denatures?

It involves the change in the enzyme's 3D structure.

What is the effect of pH on enzyme activity?

Enzyme activity is affected by pH. Extreme acidity or alkalinity can cause enzymes to denature. Enzymes work best at their optimum pH.

What is the function of the enzyme catalase?

Increases the rate of decomposition of hydrogen peroxide to water.