Questions and Answers
What are exoenzymes?
Enzymes that are secreted outside of the bacteria cell to begin chemical digestion, externally, so that the nutrients can be more readily absorbed.
What is the function of amylase?
An enzyme that converts starch into glucose.
What do starch, iodine, and amylase produce?
Glucose + clear zone.
What color does starch react with iodine?
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What is the reagent used for amylase testing?
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What type of agar is used in the amylase test?
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What is the substrate for amylase?
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What is the product of amylase activity?
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What indicates a positive result in the amylase test?
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What indicates a negative result in the amylase test?
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Which species does the amylase test commonly test for?
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Which organism has a positive result for the amylase test?
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What is casein?
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What type of agar is used in the caseinase test?
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What is the substrate for caseinase?
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What is the caseinase enzyme?
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What are the products of caseinase activity?
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What indicates a positive result in the caseinase test?
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What indicates a negative result in the caseinase test?
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Which species does the caseinase test commonly test for?
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Which organisms have positive results for the caseinase test?
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What is gelatin?
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What type of agar is used in the gelatinase test?
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When is gelatin liquified?
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What indicates a positive result in the gelatinase test?
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What indicates a negative result in the gelatinase test?
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Which species does the gelatinase test commonly test for?
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Which organisms have positive results for the gelatinase test?
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What is lipase?
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What is the substrate for lipase?
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What is the lipase enzyme?
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What are the products of lipase activity?
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What type of agar is used in the lipase test?
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What is indicated by the blue precipitate in the lipase test?
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What indicates a positive result in the lipase test?
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What indicates a negative result in the lipase test?
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Which species does the lipase test commonly test for?
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Which organisms have positive results for the lipase test?
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Study Notes
Exoenzymes Overview
- Exoenzymes are enzymes secreted by bacteria to digest food outside the cell for nutrient absorption.
Amylase
- Converts starch into glucose.
- Positive amylase test indicated by a clear zone on starch agar.
- Iodine is used as an indicator; when mixed with starch, it turns blue.
Caseinase
- Breaks down milk protein casein into amino acids.
- Positive caseinase test indicated by a transparent zone on skim milk agar.
- Casein + water + caseinase results in a positive outcome.
Gelatinase
- Gelatin is solid at room temperature; gelatinase can liquefy it.
- Positive gelatinase test indicated by liquefied gelatin in gelatine agar slants.
- Key species tested include Proteus mirabilis, Serratia marcescens, and Pseudomonas aeruginosa.
Lipase
- Converts triglycerides into fatty acids.
- Tested using spirit blue agar; a blue precipitate indicates a positive result.
- Positive result also shows a pH shift from metabolism.
Specific Organisms
- Amylase production: Bacillus subtilis is a key organism tested.
- Caseinase production: Positive results found in Staphylococcus epidermidis and Bacillus subtilis.
- Gelatinase production: Pseudomonas fluorescens and Serratia marcescens can test positive.
- Lipase production: Observed in Staphylococcus epidermidis and Bacillus subtilis.
Indicators of Reactions
- Amylase: Clear agar signifies positive; blue agar signifies negative.
- Caseinase: Clear zone indicates a positive result; no clear zone indicates negative.
- Gelatinase: Liquified gelatin signifies positive; solid gelatin means negative.
- Lipase: Blue precipitate indicates positive; no precipitate but growth signifies negative.
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Description
Test your knowledge on exoenzymes with this flashcard quiz. Each card provides definitions and examples of specific exoenzymes, including amylase and their reactions with starch. Perfect for biology students looking to reinforce their understanding of enzyme functions.
