Protein Digestion Lab Report

Introduction: The importance of digestion is to break down food to give the body nutrients that are used for energy, cell repair, and growth. The body breaks down proteins, fats, and starches from the food and drinks the body consumes every day. There are many sources of protein, most of which come from meat, eggs, and beans and they are digested into amino acids. Fats come from oils, butter, shortening, and snacks and they are broken down into fatty acids and glycerol. Starch, or carbohydrates, come from many foods found in whole grain bread, vegetables, and food that contains natural sugars (NIH).
Digestion starts in the mouth where mechanical, chewing food, and chemical, mixing food with saliva, digestion both occur simultaneously. The food then travels through the pharynx,

When the biuret reagent turns purple, that means that protein is still present and that digestion has not occurred. Test tubes 1, 2, and 4 were negative for digestion because the biuret reagent turned purple and stayed purple throughout the whole test tube. Test tube 3 tested positive for digestion because the biuret reagent turned a pinkish-purple and sunk to the bottom of the test tube, which meant that peptides were present and digestion occurred. Digestion did not occur in tubes 1 and 2 because the pH was too low for the enzymes to break down the food into peptides. Those two tubes contained HCl instead of water like the other tubes did. Even though tubes 1 and 2 were at different temperatures the result was the same. Digestion did not occur at body temperature or at room temperature when containing HCl. Tubes 3 and 4 were the same except tube 4 did not contain pepsin. Pepsin is key for digestion of proteins into peptides, therefore tube 4 did not test positive for digestion. There must be the right pH level and enzymes for digestion of proteins to occur and test tube 3 was the only one suitable for