Hand Outs of Metabolism Essay

1719 Words Jun 13th, 2015 7 Pages
Protein digestion
Protein metabolism denotes the various biochemical processes responsible for the synthesis of proteins and amino acids, and the breakdown of proteins (and other large molecules, too) by catabolism.Dietary proteins are first broken down to individual amino acids by various enzymes and hydrochloric acid present in the gastro-intestinal tract.[1] These amino acids are further broken down to α-keto acids which can be recycled in the body for generation of energy, and production of glucose or fat or other amino acids. This break-down of amino acids to α-keto acids occurs in the liver by a process known as transamination
Protein digestion occurs in the stomach and duodenum in which 3 main enzymes, pepsin secreted by the
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However fats are mainly digested in the small intestine.[16] The presence of fat in the small intestine produces hormones that stimulate the release of pancreatic lipase from the pancreas and bile from the liver which helps in the emulsification of fats for absorption fatty acids.[16] Complete digestion of one molecule of fat (a triglyceride) results in 3 fatty acid molecules and one glycerol molecule.[16]
Digestion and transport[edit]
Fatty acids are usually ingested as triglycerides, which cannot be absorbed by the intestine.[2] They are broken down into free fatty acids and monoglycerides by pancreatic lipase, which forms a 1:1 complex with a protein called colipase, which is necessary for its activity. The activated complex can work only at a water-fat interface. Therefore, it is essential that fatty acids (FA) be emulsified by bile salts for optimal activity of these enzymes.
The digestion products of triglycerides are absorbed primarily as free fatty acids and 2-monoglycerides, but a small fraction are absorbed as free glycerol and as diglycerides. Once across the intestinal barrier, they are reformed into triglycerides and packaged into chylomicrons or lipoproteins, which are released into the lacteals, the capillaries of the lymph

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