18/03/2024

• Lipids

  Elements: C,H, O

  Monomers: glycerol and fatty acids

  Polymers: Triglyceride
• Carbohydrate

  Elements: C, H, O

  Monomers: Glucose, fructose, galactose

  Polymers: Starch (storage plants), Glycogen (storage in humans), Cellulose (cell walls plants)
• Proteins

  Elements: C, H, O, N, S

  Monomers: Amino acids

  Polymers: Protein
• Enzymes

  • Biological catalyst that speeds up the rate of reaction without being used up itself
• What happens when an enzyme is denatured

  Shape of active site changes, substrate can no longer fit (no longer complementary shape), no enzyme-substrate-complex formed, enzyme cant break down substrate to form products - rate of reaction decrease
• Villi


  • Found in ileum

  Villi +Microvilli - increase SA

  Good blood supply - maintain concentration gradient

  Lacteal - absorb lipids

  Thin - short diffusion distance

  Long - more chance for products to be absorbed
• Role of bile

  Emulsify lipids- to form small droplets --> larger SA: VOL for enzyme lipase to work

  Neutralise acid from stomach

  Provide optimum pH for Lipase

  
• Salivary amylase (carbohydrates)

  Where produced: Salivary glands

  Where used/found: Mouth

  Substrate: Starch

  End-products: Maltose

  pH: 7-8
• Pancreatic amylase (carbohydrates)

  Where produced: Pancreas

  Where used/found: Duodenum

  Substrate: Starch

  End-products: Maltose

  pH: 7-8
• Maltase (carbohydrates)

  Where produced: Pancreas

  Where used/found: Duodenum

  Substrate: Maltose

  End-products: Glucose

  pH: 7-8
• Pepsin (proteins)

  Where produced: Stomach

  Where used/found: Stomach

  Substrate: Polypeptide

  End-products: Dipeptide

  pH: 1-2
• Typsin (proteins)

  Where produced: Pancreas

  Where used/found: Duodenum

  Substrate: Polypeptide

  End-products: Dipeptide

  pH: 7-8
• Peptidase (proteins)

  Where produced: Duodenum

  Where used/found: Duodenum

  Substrate: Dipeptides

  End-products: Amino acids

  pH: 7-8
• Lipase (lipids)

  Where produced: Pancreas

  Where used/found: Duodenum

  Substrates: Lipids

  End-products: Glycerol and fatty acids

  pH: 7-8
• Food tests and positive results:

  Glucose: benedict's solution, goes orange

  Starch: iodine, goes blue/black

  Lipids: ethanol, cloudy white emulsion

  Protein: Biuret test, purple
• Structures

  • Mouth
  • Oesophagus
  • Stomach
  • Duodenum
  • Ileum
  • Colon
  • Anus
  • Pancreas
  • Gallbladder
  • Appendix
• Digestion

  1. Food is chewed up by teeth

  2. Mechanical and chemical digestion occurs
• Mouth


  Food is chewed up by teeth here and swallowed, mechanical and chemical digestion occurs
• Oesophagus


  Tube that connects the mouth to the stomach
• Stomach


  This organ contains the enzymes pepsin (a protease) and also hydrochloric acid to kill bacteria
• Duodenum


  This is where the food comes into contact with bile
• Ileum

  This is where absorption of the food molecules into the bloodstream takes place
• Colon(large intestine)


  Water from the waste food is absorbed here
• Anus


  Faeces leave the body here
• Pancreas


  This organ produces amylase, lipase and protease enzymes and releases them into the duodenum
• Gallbladder


  Where the bile is stored
• Appendix


  This part of the large intestine has no use in humans except to cause a lot of pain if it bursts
• Salivary glands produce saliva which contains the enzyme salivary amylase