Digestion

• Describe and explain two features you would expect to find in a cell specialised for absorption

  Folded membrane which increases SA - increasing absorption

  Membrane bound enzymes which maintain the concentration gradient - increasing absorption
• Why is digestion neccessary?

  Molecules are large and insoluble before digestion, digestion breaks these down into small and soluble components. This can then be taken around the body and used in body regulation.
• Describe carbohydrate digestion

  Hydrolysed glycosidic bonds using the enzyme amylase.

  Membrane bound disaccharides are found on the surface of epithelium cells and line the ileum. They breakdown disaccharides into monosaccharides. Carried by specific transporter proteins into the ileum.
• Define a membrane bound disaccharide.

  Enzymes attached to a cell membran
• Describe lipid digestion.


  Hydrolysed esther bonds by lipase

  Bile salts can help emulsify lipids and form small droplets with increases SA and allows faster breakdown

  Components then mix with bile salts to form micells further increasing SA
• Where are amylase produced and secreted?


  Salivary glands and pancreas which are secreted into the small intestine
• Where are lipase produced and secreted?

  Pancreas and secreted in small intestine
• Describe protein digestion


  Endopeptidase: Hydrolyse peptide bonds within a protein

  Exopeptidase: Hydrolyse peptide bonds at the end of a protein

  Dipeptidase: Hydrolyse peptide bonds between a dipeptide
• How are monosaccharides and amino acids absorbed?

  By co-transport and facilitated diffusion
• How are glucose and galactose absored?


  Through sodium co-transport
• How is fructose absorbed?

  Facilitated diffusion using a different transport protein
• How are monoglycerides and fatty acids absorbed?

  Using micells which transport them to the epithelium and when broken they release the contents into the epithelium membrane