Digestion & absorbance

• What are the three main macromolecules involved in digestion for AQA biology?

  • Carbohydrates
  • Lipids
  • Proteins
• What is the definition of digestion?

  Hydrolysis of large insoluble molecules
• What happens to large insoluble molecules during digestion?

  They are hydrolyzed into smaller soluble molecules
• What are the two types of enzymes mentioned for carbohydrate digestion?

  Amylase and membrane-bound disaccharidases
• Where is amylase produced?

  In the pancreas and salivary glands
• Where does carbohydrate digestion begin?

  In the mouth
• What does amylase do to carbohydrates?

  Hydrolyzes polysaccharides into disaccharides
• What is the first part of the small intestine where digestion continues?

  Duodenum
• What do membrane-bound disaccharidases do?

  Hydrolyze disaccharides into monosaccharides
• What do endopeptidases do?

  Hydrolyze peptide bonds within protein chains
• What is the role of exopeptidases?

  Hydrolyze peptide bonds at the ends of chains
• Where does protein digestion start?

  In the stomach
• What is unique about lipid digestion compared to carbohydrates and proteins?

  It involves both chemical and physical breakdown
• What enzyme is responsible for lipid digestion?

  Lipase
• What do bile salts do during lipid digestion?

  Emulsify lipids into smaller droplets
• Why is emulsification advantageous for digestion?

  It increases surface area for faster hydrolysis
• What happens to fatty acids and monoglycerides after hydrolysis?

  They form micelles for absorption
• What are micelles made of?

  Fatty acids, monoglycerides, and bile salts
• How do fatty acids and monoglycerides enter epithelial cells?

  By diffusion through the plasma membrane
• Where are triglycerides reformed after absorption?

  In the Golgi apparatus
• What is a chylomicron?

  A triglyceride combined with a protein
• How are chylomicrons released from epithelial cells?

  By exocytosis
• What transports lipids after absorption?

  Lacteals or lymph vessels
• Where do lipids eventually drain after being absorbed?

  Into the capillary system