Human_Nutrition_Midterm_2-1 - Chapter 7 Study Guide...

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Chapter 7 Study Guide Proteins 1. How is protein synthesized from DNA? Part of DNA code (gene) is transcribed to mRNA in the nucleus> mRNA leaves the nucleus and travels to the cytosol> Ribosomes in the cytosol and Rough ER read the mRNA code and translate that into directions for a specific order of amino acids in a polypeptide chain>To produce the polypeptide, tRNA brings the appropriate amino acid to the ribosome as dictated by the mRNA code. The amino acid is added to the existing amino acid chain, which begins with the amino acid methionine> When synthesis of the polypeptide is complete, it is released from the ribosome.> Often the polypeptide will undergo further cell metabolism in order to function as a specific body protein once it folds into its active form. 2. What are the components of an amino acid? What unique chemical is in protein but not carbohydrate and fat? Amine group(contains nitrogen), acid group, an a “R” group: side chain (changes with each amino acid). 3. What is the difference between an essential and a non-essential amino acid? See below definitions 4. What would happen to protein synthesis is an essential amino acid is missing in the diet? Would develop phenylketonuria. 5. Describe the primary and secondary functions of protein. Primary: provide 9 essential amino acids, nonessential amino acids, and nitrogen to make nonessential amino acids. Builds body components, immune function, hormones, and enzymes. Secondary: Fluid balance, buffers, and make energy. 6. Name a hormone that is a protein. insulin 7. Describe the type of protein digestion that takes place in the stomach and the small intestine.
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Stomach: partial protein digestion by the enzyme pepsin and stomach acid; Gastrin stimulates release of pepsinogen from the chief cells and pepsinogen is converted to pepsin by the stomach acid. Pepsin breaks down proteins into peptones. Small intestine: Final digestion of protein to amino acids takes place mostly inside the cells of the small intestine. Pancreas releases protein splitting enzymes (trypsin, chymotrysin, and carboxypeptidase) into the duodenum. These enzymes break peptones into smaller peptides and amino acids that are now ready for absorption. 8. What is the final end product of protein digestion that is absorbed into the bloodstream? Amino acids 9. Where do these end products go after they are absorbed into blood? Sent to the liver through the portal vein.
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This note was uploaded on 04/22/2008 for the course HUMN NTR 310 taught by Professor Smith during the Spring '08 term at Ohio State.

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Human_Nutrition_Midterm_2-1 - Chapter 7 Study Guide...

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