Proteins

• Proteins are special molecules as they have fixed shapes
• Made up of longchains of different animo acids
• There are 21 different amino acids, so different combinations lead to different proteins
• Proteins have 4 structures in the body:
  • Muscles & tendons
  • Hormones (eg. insulin)
  • Antibodies
  • Enzymes

• Enzyme- A protein molecule that acts like a biological catalyst to speed up chemical reactions
• Substrate- Reactant that fits into the active site of the enzyme
• Active site- where the enzyme and reactant fit and react together
• Lock and key- The substrate and enzyme bind together and the enzyme splits the substrate

• As temperature increases, the rate of digestion increases as the enzymes have more energy
• The wrong pH and/or temperature canchange the shape of the active site so the substrate can no longer fit
• Enzymes work best in acidic conditions

Amylase:

• Breaks down carbs
• Makes sugars
• Found in the small intestine

Protease:

• Breaks down proteins
• Makes animo acids
• Found in the small intestine and stomach

Lipase:

• Fats are digested by the enyzme lipase
• Lipase is found in the mouth, stomach and pancreas
• Fats (lipids) are broken down into glycerol and fatty acids

Bile:

• Bile is an alkaline fluid produced by the liver
• It neutralises acids
• It also emulsifies fats- breaks them down into smaller droplets
• This is so the fat has more surface area to be digested faster

Detergents:

• They may contain protease and lipase
• Break down stains and work at lower temperatures, so are cheaper

• Protease, carbohydrase and isomerase are used in the food industry
• Enzymes can be used to diagnose and treat diseases