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17 Cards in this Set
- Front
- Back
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Which enzyme is used in protein digestion? Where is it found?
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The enzyme, pepsin, is used and is found in the stomach. It functions at very low pH levels. (since pH in stomach as we know is very low!)
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How were conditions of the stomach simulated in order to test for proteins?
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Hydrochloric acid, (HCl), was added to simulate the acid environment of the stomach.
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What is the sequence of digestion that pepsin undergoes in the stomach?
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Pepsin firsts digests proteins into peptides, and then it will eventually turn peptides into amino acids.
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What is the reagent needed to detect for the presence of proteins? What happens to the reagent if it detects proteins?
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The reagent that detects if proteins are present is the blue colored “Biuret reagent”. When it combines with the peptide bonds found in protein and peptides, it changes to purple.
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What happens when the reagent combines with many peptide bonds?
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When combined with many peptide bonds in proteins, the reagent turns purple, the same color as proteins since proteins are made up of many peptide bonds
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What happens when the reagent combines with only a few peptide bonds?
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few peptide bonds in proteins comes out as purple-pink
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If a test comes out "negative" and does not find any proteins, what color is the test tube?
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The test tube is still blue from the Biuret Reagent since the pepsin did not detect any proteins
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What color do amino acids turn when the Biuret Reagent is added?
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Trick question: since amino acids do not contain peptide bonds, the reagent does not combine with anything and shows the negative blue color
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What protein was digested from the test we did in class?
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The protein that was digested was albumin found in blood and egg whites
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Albumin turns Purple when:
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Biuret Reagent is added. Purple means that it is positive for proteins. No digestion has occured.
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Albumin turns Pinkish- purple when:
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Pepsin is added. Albumin was digested to peptides by the pepsin. So pinkish purple signifies the presence of peptides.
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if the test tube contains free amino acids (not linked together) the color will be... ?
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blue- negative
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If digestion of albumin occurred and peptides were formed, the color will be...?
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purple-pink.
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If digestion of albumin was complete and amino acids were released, the color will be...?
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blue- negative
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What does the Biuret Reagent used to test for?
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Biuret reagent tests for the presence of peptide bonds found in protein and peptides.
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How much time does pepsin need to digest albumin?
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tubes need to be incubated at 98.6F for 1 hour to give the pepsin time to digest the albumin
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Biuret reagent is made up of which two elements?
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Biuret reagent consists of equal volumes of 3% copper sulfate (CuSO4) and 15% potassium hydroxide (KOH).
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