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34 Cards in this Set
- Front
- Back
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What is the reason behind having the litmus milk reactions?
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To differentiate amongst the 10 bacteria that breakdown milk substrates for metabolisms and distinguishing the end products of each bacteria.
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What are the components of milk?
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Lactose, casein, lacto-albumin, and lactoglobulin.
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What is the pH indicator in litmus milk?
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Litmus
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What is litmus?
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pH indicator; without the presence of oxygen, it acts in its place by readily accepting ions
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What is the color of neutral pH in litmus milk (control)
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Purple
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Name all the biochemical changes that litmus milk can show (hint 6)
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Lactose fermentation, gas production, litmus reduction, curd formation, proteolysis, alkaline reaction
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What is lactose fermentation?
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To use lactose for metabolism
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What enzyme is used to break apart lactose?
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B-galactosidase
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What 2 sugars form lactose?
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Glucose & galactose
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What is the end product of lactose fermentation?
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Lactic acid & pyruvate
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What pH environment (acidic, alkaline, neutral) is created with the end product of lactose fermentation and what color does it produce within the media?
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Acidic - pink
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Which gases can be produced during lactose fermentation?
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CO2 & H2
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What can be shown to distinguish if a bacteria created gas during lactose fermentation?
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Separations and/or fissures within the curd.
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When a bacteria reduces litmus, what happens?
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The media turns from purple to white because litmus accepts hydrogen ions during fermentation.
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How does acid curd formulate?
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Lactic acid and other acids cause precipitation of casein that forms CALCIUM CASEINATE; this is shown as a hard insoluble clot.
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How does rennet curd formulate?
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Rennin (enzyme) acts on casein and turns it into paracasein; with calcium present, it then forms into CALCIUM PARACASEINATE and is shown as a soft, semisold, insoluble clot.
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What is proteolysis/peptonization?
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The usage of protein as an energy source by breaking it down for metabolic purposes.
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What type of enzyme breakdown casein during proteolysis/peptonization?
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Proteolytic enzymes
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When breaking down casein during proteolysis/peptonization, what is released as an end product?
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Ammonia
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What type of pH environment (acidic, alkaline, neutral) is produced during proteolysis/peptonization and what color is produced?
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Alkaline - deep purple or blue with a brown translucent media body
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What can be shown in the media when amino acids are broken down?
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Deep purple/blue top with brown translucent media body
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What happens in a alkaline reaction?
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Breakdown of protein to shorter polypeptide chains, which then releases ammonia and gives its' deep purple/blue look.
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Which bacteria showed acid, reduction, curd, gas during litmus milk reaction?
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E. coli
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What did E. coli exhibit during litmus milk reaction?
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Acid, reduction, curd, gas
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Which bacteria showed acid, reduction, curd during litmus milk reaction?
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L. lactis, E. faecalis
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What did L. lactis & E. faecalis exhibit during litmus milk reaction?
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Acid, reduction, curd
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Which bacteria showed acid, reduction during litmus milk reaction?
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S. carnosus
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What did S. carnosus exhibit during litmus milk reaction?
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Acid, reduction
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Which bacteria showed acid during litmus milk reaction?
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E. aerogenes
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What did E. aerogenes exhibit during litmus milk reaction?
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Acid
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Which bacteria showed peptonization/proteolysis during litmus milk reaction?
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B. subtilis
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What did B. subtilis exhibit during litmus milk reaction?
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Peptonization/proteolysis
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Which bacteria showed alkaline during litmus milk reaction?
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P. vulgaris, A. faecalis, C. xerosis, P. aeruginosa
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What did P. vulgaris, A. faecalis, C. xerosis, P. aeruginosa exhibit during litmus milk reaction?
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Alkaline
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