Digestive enzymes and their actions Revision Notes | GCSE OCR Foundation Biology

What this lesson covers

Learning about the different types of digestive enzymes, where they are produced, what they break down and how their products are used in the body

• Recall the sites of production and actions of amylase, proteases and lipases
• Explain how digestive enzymes convert food into small soluble molecules
• Describe the specific breakdown products of carbohydrases, proteases and lipases
• Apply knowledge of enzyme actions to explain digestion processes

Key ideas to keep in view

Use this lesson to stay inside B1.2 What happens in cells (and what do cells need)? while connecting the detail back to the wider B1: Cell level systems topic.

• B1: Cell level systems
• B1.2 What happens in cells (and what do cells need)?
• GCSE OCR Foundation Biology

Lesson notes preview

Read the core explanations from Digestive enzymes and their actions before testing yourself from memory.

• Picture trying to push a football through a letterbox. That's what your body faces with food - the molecules in your sandwich are massive compared to what can actually get into your bloodstream. Starch molecules contain thousands of glucose units linked together. Proteins are chains of hundreds of amino acids. Your...
• This is where digestive enzymes become essential. They act like molecular scissors, chopping up these giant food molecules into pieces small enough to pass through your intestinal wall and enter your blood.
• Biological catalysts that break down large food molecules into smaller, soluble molecules that can be absorbed into the bloodstream
• Trap: Many students think enzymes 'destroy' food. Actually, they break bonds to release smaller, useful molecules that your body can absorb and use.
• 2. The Three Main Types of Digestive Enzymes
• Your digestive system uses three main types of enzymes, each targeting a specific type of food molecule. Think of them as specialist tools - each one designed for a particular job.
• Enzymes that break down carbohydrates into simple sugars. The most important example is amylase, which breaks down starch
• Enzymes that break down proteins into amino acids. Found in the stomach (pepsin), pancreas and small intestine
• Enzymes that break down lipids (fats and oils) into glycerol and fatty acids. Mainly produced by the pancreas
• Each enzyme is highly specific - amylase only works on starch, not proteins or fats. This specificity comes from the enzyme's active site, which has a complementary shape to its substrate molecule.

Continue through the topic

Move to the related lessons or back to the topic page when you need the wider sequence before exam-style practice.