Energy Outline

Energy Outline - Small intestines fats(triacylglycerols are...

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CHEMISTRY 120 – CHAPTER 18 – REVIEW Metabolic pathways and energy production Metabolism: Chemical reactions that take place in living cells to break down or build up molecules. Stage 1: Digestion of proteins, polysaccharides and lipids. o Catabolism: converting large molecules to small one that can be absorbed by the body (also called digestion). o Digestion of carbohydrates: Mouth: amylase brakes down amylose and amylopectin to dextrins, maltose and glucose. Stomach: stomach acids denature (ruin) amylase. No digestion of carbohydrates. Small intestines: amylase from pancrease further hydrolyses medium sized glucose polymers (dextrins) to glucose. Sucrase hydrolyzes sucrose to glucose and fructose. o Digestion of fats: fats are a concentrated form energy! When needed they are broken down and converted to glucose. Mouth: no fat digestion takes place in the mouth. Stomach: no fat digestion takes place in the stomach.
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Unformatted text preview: Small intestines: fats (triacylglycerols) are converted to 2 free fatty acids and 1 fatty acid still attached to glycerol with the enzyme lipase . • Bile salts: dissolve fat droplets to form smaller droplets ( micelles ) which can then be broken down by lipase. o 2-FA and 1-FA-glycerol are absorbed by intestinal wall. They then recombine to a triacylglycerol which is then coated with proteins ( chylomicrons – a lipoprotein) to make it water soluble. It is transported in blood. o Digestion of proteins: Mouth: no protein digestion occurs in the mouth. Stomach: stomach acid denatures (deactivates) proteins and activates pepsin. • Pepsin: an enzyme that breaks down proteins into smaller chains. Small intestines: trypsin and chymotrypsin break down remaining polypeptides into amino acids which are absorbed by intestine walls. • Trypsin and chymotrypsin: cleave peptide bonds in proteins....
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