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Cards In This Set
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What is Gelatin?
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1. a high-molecular-weight
2. water-soluble protein derived from collagen 3. a long fibrous molecule 4. a component of connective tissues in animals 5. it is translucent and tasteless |
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What happens when Gelatin is chilled in ice or in the fridge?
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It forms cross-links to create a semisolid gel
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What could Gelatin potentially provide for bacteria?
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As a protein, it could provide a rich source of amino acids and peptides to bacteria
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Why can't the protein just be transported in to the bacteria?
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It's too large and has to be broken down
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Explain how the Gelatin gets into the bacteria?
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1. Broken down by extracellular proteases like gelatinase
2. Gelatinase hydrolyzes bonds in the gelatin molecule to produce smaller peptides and amino acids 3. Now smaller, they can diffuse more easily through medium and be transported into the bacterial cell |
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What medium is used to detect the production of an extracellular gelatinase?
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Nutrient gelatin medium
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How is this nutrient medium produced?
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It's produced by combining nutrient broth and gelatin
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Does this medium contain agar?
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No
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What happens to this medium at room temp?
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It can be liquid to slightly viscous
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What happens to this medium after refrigeration?
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It gels and forms semisolid
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After this medium is inoculated, how long is it incubated?
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24 to 48 hours or longer
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After incubation what do we do with the tubes?
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Place them in the fridge or on ice for 20 to 30 minutes
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If the tube gels after incubation and refrigeration, what does this indicate?
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The organism is negative for the enzyme gelatinase, the enzyme is not present; therefore the tube gels as expected
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If the tube runs when tilted after incubation and refrigeration, what does this indicate?
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1. The test is positive and the organism produced the enzyme gelatinase.
2. The enzyme was secreted into the medium and hydrolyzed the gelatin to produce short peptides and amino acids. 3. The shorter strands cannot cross-link effectively to produce the gel and therefore the medium remains liquid |
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After inoculation, where do we place the tubes?
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In the incubator, NOT the refrigerator
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