Bio chem Quiz 1

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  1. Starch (amylase) hydrolysis test
    • Tests if the bacteria has a exoenzyme (a enzyme that leaves the cell to break down big molecules like starch) amylase.
    • Once the bacteria has grown but grams iodine
    • positive reaction there will be a clearing around the growth (because it ate the starch)
    • Negative is no clearing around it once you add the iodine.
  2. casein hydrolysis
    • Casein is what makes milk opaque
    • This test tests for bacteria that release a exoenzyme caseinase (breaks down the casein in the culture)
    • A postive reaction will have clearing around the bacterial growth (because it will break down the casein in the milk agar)
    • Negative willl have no clearing around the bacterial growth.
  3. Indole Test (tryptophan test)
    • This tests to see if the bacteria create tryptophanase that is able to break down tryptophan.
    • Once the broth has grown add 10 drops of kovac's reagant. The bacteria that does this uses pyruvate and ammonia as food.
    • If it's positive there will be a cherry red ring at the top of the tube
    • Negative reaction will have a green or yellow ring
  4. Urea hydrolysis
    • Some enteric bacteria have a enzyme called urease that breaks down urea into CO2 and ammonia.
    • Phenol red is also used in it as a pH indicator red to yellow is a acidic 6.8pH or lower bright pink is 8.1pH or higher
    • A positive result is bright pink a negative result is yellow or beige (beige meaning medium)
  5. Catalase production test
    • aerobic, facultative anaerobic and aerotolerant bacteria have protective enzymwa that reduce O2 toxicity by converting these derivatives to less harmful products
    • this test tests for the presense of catalase
    • Positive is if bubbles are produced
    • negative is if no bubbles are produced
  6. Oxidase test
    • This tests for the abiltiy for bacteria to produce cytochrome oxidase
    • Positive if it turns blue
    • Negative if it doesn't turn a color
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Bio chem Quiz 1
notecards for biochem test part 1 quiz 1
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