Digestion

• What enzyme hydrolyses carbohydrates?

  Amylase and Membrane bound Disaccharides.
• Where is amylase produced?

  Pancreas, salivary glands
• Where does the digestion of amylase begin, describe the process?

  In the mouth- amylases hydrolyse polysaccharides into disaccharides such as maltose. By hydrolysing glycosidic bonds.
• What happens after amylase hydrolyses polysaccharides in the mouth?

  This is then swallowed, goes in to the stomach and digestion continues in the duodenum.
• What is the duodenum?

  The first part of the small intestine.
• What happens in the duodenum to disaccharides.

  Membrane bound disaccharides hydrolyse disaccharides into monosaccharides in the ileum.
• Name 3 membrane bound disaccharides- and their function.

  Sucrase- hydrolyse sucrose into fructose & glucose

  Lactase- hydrolyse lactose into galactose & glucose

  Maltase- hydrolyses maltose into glucose
• Describe how membrane bound disaccharidases work.

  They are attached to the cell-surface membranes of the epithelial cells lining the small intestine.
• What enzyme hydrolyses proteins?

  Endopeptidases

  Exopeptidases

  Membrane bound dipeptidases
• What is the function of endopeptidase?

  Hydrolyses bonds between amino acids in the middle of a polymer chain.
• What is the function of exopeptidases?

  Hydrolyses peptide bonds between amino acids at the end of a polymer chain.
• What is the function of membrane bound dipeptidases?

  Hydrolyses peptide bonds between two amino acids.
• Where does proteins digestion begin?

  Begins in the lumen of the stomach (by endopeptidase pepsin), this is secreted along with HCL to proved the optimum acidic environment for the enzyme.
• What happens after protein digestion in the stomach?

  Fluid secreted by the pancreas travels to the small intestine- neutralising stomach acid increasing pH.
• What does the pancreatic juice contain?

  Endopeptidases and exopeptidases.
• Where do endo and exopeptidases from the pancreatic juice work?

  The small intestine.
• Where are dipeptidases found?

  Within the cell surface membrane of the epithelial cells in the small intestine.
• What does lipid digestion involves the action of?

  bile salts

  lipase enzymes
• Describe emulsification

  Physical digestion Bile salts bind to the fatty liquid and breaks the fatty droplets into smaller ones (micelles).
• Where does emulsification occur?

  In the small intestine
• what happens prior to emulsification in the small intestine?

  In the stomach, solid lipids are turned into a fatty liquid consisting of fat droplets - but this is not digestion.
• Where is bile made, what does in contain, where is it stored, and where is it secreted from.

  Bile (containing bile salts) is made in the liver, stored in the gallbladder and is secreted through the bile duct, to the small intestine.
• Where does the digestion of lipids take place?

  In the lumen of the small intestine.
• Why is emulsification necessary?

  Increase the surface area of the fatty droplets for action of digestive enzymes.
• Describe the function of lipase enzymes.

  Hydrolyse the ester bonds in triglycerides to monoglycerides and fatty acids.
• Where is lipase produced?

  Pancreas
• What are micelles?

  water soluble vesicles formed of the fatty acids, glycerol, monoglycerides and bile salts.
• What is the function of micelles?

  They deliver the fatty acids, glycerol and monoglycerides to the epithelial cells of the ileum for absorption.
• Describe the structure of micelles.

  Non- polar so can diffuse through phospholipid bilayer

  Small spherical structures

  Micelles constantly break up and reform; when they break apart their lipid-soluble content.