The role of enzymes

What is an enzyme?

• An enzyme is a biological catalyst

• It speeds up chemical reactions

• It is not used up and remains chemically unchanged

Why are enzymes described as biological?

• They function in living organisms

• They are made by cells via protein synthesis

Why are enzymes described as catalysts?

• They increase the rate of reaction

• They are not consumed

• They can be reused repeatedly

What type of molecule are enzymes?

• Enzymes are globular proteins

• They have a complex tertiary structure

• The structure creates a specific active site

What is the difference between tertiary and quaternary enzymes?

• Some enzymes consist of one polypeptide → tertiary structure

• Some consist of multiple polypeptides → quaternary structure

How do enzymes control metabolism?

• Metabolism occurs as a sequence of reactions called a metabolic pathway

• Each step is catalysed by a specific enzyme

• This forms a biochemical cascade

Why are enzymes essential for life?

• Almost all metabolic reactions are enzyme-controlled

• Without enzymes, reactions would be too slow to sustain life

How are enzymes made in cells?

• Enzymes are synthesised by protein synthesis

• Ribosomes assemble amino acids into polypeptides

• Polypeptides fold into functional enzymes

Where do enzymes work in organisms?

• Some enzymes act inside cells

• Some enzymes act outside cells

• This gives rise to intracellular and extracellular enzymes

What are intracellular enzymes?

• Enzymes that remain inside the cell

• Catalyse reactions in metabolism and respiration

What does catalase do and where does it act?

• hydrogen peroxide is produced as a by product of many chemical reactions

• Catalase breaks down hydrogen peroxide → water + oxygen

• Prevents toxic buildup of hydrogen peroxide

• Acts inside cells (intracellular)

What are extracellular enzymes?

• Enzymes that are secreted from cells

• Catalyse reactions outside the cell

• Commonly found in the digestive system

What does amylase do and where does it act?

• Amylase breaks down starch into maltose

• Secreted in saliva and pancreatic juice

• Acts outside cells (extracellular digestion)

what are anabolic enzymes

making new molecules

what are catabolic enzymes

breaking down molecules