Digestion & Absorption

• "Define digestion" "the hydrolysis of large, insoluble molecules into smaller molecules that can be absorbed across cell membranes"
• "Which enzymes are involved in carbohydrate digestion? where are they found" "Amylase in mouth membrane-bound disaccharidases"
• "What needs to happen before lipids can be digested?" "they must be emulsified by bile salts produced by the liverthis breaks down large fat molecules into smaller, soluble molecules called micelles, increasing surface area"
• "Which enzymes are involved in protein digestion?" "Endopeptidases, Exopeptidases, Membrane-Bound Dipeptidases"
• "What is the role of Exopeptidases?" "break between specific amino acids at the end of a polypeptide"
• What is the role of the Dipeptidases? break dipeptides into amino acids
• How are certain molecules absorbed into the ileum despite a negative concentration gradient through co-transport
• "Which molecules require co-transport?" amino acids monosaccharides
• "Explain how sodium ions are involved in co-transport" "Sodium ions are actively transported out of the cell into the lumen, creating a diffusion gradientNutrients are then taken up into the cells along with Na+ ions"
• "Why do fatty acids and monoglycerides not require co-transport" "the molecules are non-polar, meaning they can easily diffuse across the membrane of the epithelial cells through simple diffusion"
• "How is food chemically broken down?" "hydrolysis of large insoluble molecules into small soluble moleculescarried out by specific enzymes"
• What are carbohydrates broken down into? disaccharides and then monosaccharides
• "Where is amylase produced and where is it released to?" "Salivary glands - releases into mouthPancreas - releases into small intestine"
• What are membrane-bound disaccharidases? enzymes that are attached to cell membranes of epithelial cells lining the ileum
• "Where is lipase made and where is it digested?" "made in pancreasworks in lumen of small intestine"
• "What evidence from the diagram shows that the enzyme is an endopeptidase" "bonds have been broken within the chain and not
• at the ends"
• What reaction is catalysed by endopeptidase "hydrolysis of water;
• breaks peptide bond"
• Explain why it is an advantage for a polypeptide to be digested by an endopeptidase before an exopeptidase creates more ends (for exopeptidase to act on)
• Explain the advantage of peptidases being secreted in an inactive form cell membranes contain proteinsactive peptidase may digest these proteins
• Explain why it is a disadvantage for amylase to not secrete in an inactive form? amylase digests starchstarch not found in animal cells
• "Explain how the movement of Na+ out of the cell allows the absorption of glucose into
• the cell lining of the ileum." "Maintains a concentration gradient
• for Na+ from ileum into cellNa+ moving in by facilitated diffusion, brings glucose with it"
• "Describe the role of micelles in the absorption of lipids" "Micelles include bile salts and fatty acids which makes the fatty acids more soluble in waterthey carry fatty acids to epithelial cells of the ileumthey help to maintain higher concentration</...
• ileumFatty acids absorbed by diffusion"
• "Explain the advantages of lipid droplet and micelle formation" "Droplets increase surface areas for enzyme action So faster digestion of lipidsMicelles carry fatty acids and glycerol through membrane to intestinal <span style=""col...
• Describe the ileum "long muscular tube, further digestion, inner
• walls are folded into villi (larger
• surface area)villi are covered in microvilli"
• Describe physical breakdown in digestion "food is broken down by the teeth into smaller
• pieces, increases the surface area for enzymes to work"
• What is carbohydrate digestion? hydrolyses carbohydrates into monosaccharides
• "Describe the digestion of starch" "amylase hydrolyses alternate glycosidic bonds in starch to form maltose-> it also contains
• mineral salts to maintain a
• neutral pHFood enters the stomach (this is acidic and denatures the amylase)Food then passes into the small intestine
• where it mixes with pancreatic
• juice, pancreatic
• amylase hydrolysis of starch continuesPancreatic juice contains minerals to maintain a neutral pHMuscles in the intestine wall push food along