Enzymes and Digestion

• What is the function of the rectum in the digestive system?

  Stores faeces before egestion
• What should have been removed from food by the time it reaches the rectum?

  Water and nutrients
• What is the difference between chemical and physical digestion?

  Chemical digestion breaks down molecules
• Describe the structure and function of the major parts of the digestive system.

  • Oesophagus: Transports food to stomach
  • Stomach: Churns food and begins digestion
  • Small Intestine: Absorbs nutrients
  • Large Intestine: Absorbs water and forms faeces
  • Rectum: Stores faeces before egestion
  • Anus: Egests faeces
• How does mastication help with digestion?

  It breaks food into smaller pieces
• Where else does physical digestion occur besides mastication?

  In the stomach
• What is hydrolysis in digestion?

  Breaking down molecules into smaller ones
• Why is it necessary to make molecules soluble during digestion?

  To allow absorption in the intestines
• What do enzymes do in digestion?

  They chemically digest large molecules
• What are the main types of enzymes involved in digestion?

  Carbohydrases, proteases, lipases
• Why must enzymes be added in the correct sequence during digestion?

  To ensure proper breakdown of nutrients
• What does amylase do to starch?

  Hydrolyses starch to maltose
• What maintains the optimal pH for amylase in saliva?

  Mineral salts
• What happens to amylase once food is swallowed?

  Stomach acid denatures amylase
• What is added to food when it passes into the small intestine?

  Pancreatic juices
• What is the role of pancreatic amylase?

  Continues to hydrolyse starch
• What does maltase do to maltose?

  Hydrolyses maltose into α-glucose
• Would amylase work on lactose?

  No, it works on starch only
• What do lipases do in lipid digestion?

  Hydrolyse ester bonds in triglycerides
• What do bile salts do in lipid digestion?

  Emulsify lipids into micelles
• How do bile salts increase the rate of lipase action?

  By increasing surface area of lipids
• What are the substrates and enzymes involved in carbohydrate digestion?

  • Starch: Amylase (mouth & small intestine) → Maltose
  • Maltose: Maltase (ileum) → Glucose + Glucose
  • Sucrose: Sucrase (ileum) → Glucose + Fructose
  • Lactose: Lactase (ileum) → Glucose + Galactose
• What is the site of action and enzyme location for starch digestion?

  • Site of Action: Mouth & small intestine
  • Enzyme Location: Secreted (salivary glands, pancreas)
• What is the site of action and enzyme location for maltose digestion?

  • Site of Action: Ileum (small intestine)
  • Enzyme Location: Membrane-bound (epithelial brush border)
• What is the site of action and enzyme location for sucrose digestion?

  • Site of Action: Ileum
  • Enzyme Location: Membrane-bound
• What is the site of action and enzyme location for lactose digestion?

  • Site of Action: Ileum
  • Enzyme Location: Membrane-bound
• What do bile salts do in lipid digestion?

  Emulsify lipids into droplets called micelles
• How do bile salts increase the rate of lipase action?

  By increasing surface area for enzyme action
• What are the products of starch digestion?

  • Maltose
  • Glucose
  • Fructose
• What enzyme hydrolyzes starch?

  Amylase
• Where is amylase secreted?

  In the mouth and small intestine
• What is the function of maltase?

  Hydrolyze maltose into glucose
• Where does maltase act?

  In the ileum (small intestine)
• What type of bond does lipase break?

  Ester bond
• What are the products of triglyceride hydrolysis?

  2 fatty acids and 1 monoglyceride
• Why is lipase considered a hydrolytic enzyme?

  It uses water to break bonds
• Where does lipase work in the digestive system?

  In the small intestine
• Why is lipid breakdown considered chemical digestion?

  It involves breaking chemical bonds using enzymes
• How can we speed up lipid hydrolysis?

  Increase temperature, emulsify lipids, or add more lipase
• What is emulsification?

  Breaking large fat globules into smaller droplets