Quiz 5 Flashcards by Chelsea Roxburgh

There are two types of short term stock cultures what are they called?

Working stock culture

Reserve stock culture

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Working stock culture contains what 2 possible ingredients?

typticase soy or nutrient agar slant

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Fresh reserve culture should be prepared every ________

month

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There are two types of long term stock culture storage what are they called?

Freeze drying (Lyphilization) and freezing

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Why is a cryoprotectant like glycerol used in a storage medium that is freeze dryed?

To prevent formation of mini-ice crystals that can damage microbial cell membranes

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Bacteria stored at -20C can be revived from cold storage for how long?

1-2 years (can be recultured and prepared for another round of freezing)

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Non-Fastidious @ -70C maintain viability for how long?

5yrs

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Fastidious @ -70c maintain viability for how long?

3yrs

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is -20 or -70 preffered?

-70

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Cell vibability is much higher on a what?

agar slant

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What type of fridge will reduce viability

self defrosting feidge

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WHat can’t strict anerobes do to reactive forms of oxygen created during metabolism

detoxify

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What is the technique called for culturing anaerobes using a broth supplement with the reducing agent

thioglycollate broth

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thioglycollate reacts with ____________ to make _________ incubate for how long?

oxygen, water, 48hrs

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anerobic culture: pink or blue means what? and colourless means? What do you do for 1min if there is colour?

oxygen present, oxygen absent, boil.

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How long to incubate gas pak anaerobic system?

24-48hrs 35c

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Explain gas pak anaerobic system

chemical reaction to consume free oxygen gas in a sealed jar

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gas pak anaerobic system - what is added to the chemicals in the envelope to activate reaction?

water

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gas pak anaerobic system - if there is no moisture on the inside of the jar what do you do?

start again

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gas pak anaerobic system - what two things are produced at the end of the reaction?

Hydrogen and CO2

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gas pak anaerobic system - what colour does the indicator strip turn if pressence of oxygen

blue

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Plants store glucose as very large molecules called _______

starch

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Starch is made of _________

amylose

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Amylose is a long branched ____________

polymer

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When plants dies bacteria in the soil digest the ________ in the plants via an extracellular enzyme called __________

starch,amylase

What are the products of digestion of starch in plants?

Glucose and maltose

Glucose and maltose get transported across the __________ where they are used for _________

bacterial plasma membrane, energy and construction of other biomolecules

Starch is detected by adding ________

iodine

What will happen to starch if bacteria produce amylase?

Consumed after incubation

If no starch is detected? (Positive hydrolysis of starch) what would the colour be? and what if starch is present?

colourless, purple

starch hydrolysis - fat fuzzy snake means? | normal snake means?

positive, negative

If the iodine is yellow rather than brownish orange what does that mean?

Iodine is old - throw it out

Objective of the Citrate Utilization test.

To see if bacterium can use citrate as a sole source of carbon and energy

Membrane associated transporter for citrate utilization?

citrate permease

In the cytoplasim enzymes convert citrate to

pyruvate and CO2

If the bacteria use the citrate and CO2 combines with Na that makes what alkaline compound?

NaCO3

NH4+ is built by ________

enzymes

In an alkaline solution bromothymol blue turns

blue

Citrate utilization test - green to blue indicates? Green indicates?

positive test, negative

Citrate utilization test - what media is used at incubation details?

Simmons citrate agar slant. 35C 4 days

Indole (triptophan degrdation) test - to determine the ability of bacteria to split tryptophan (amino acid) into

indole and pyruvic acid

write out the equation of the indole test

tryotophan + 1/2 02 ------tryptophanase------pyruvate + NH3 + indole

indole test what reagent is used and incubation times?

kovacs, 24-48hrs - 35c

indole test - red layer means? no red layer means?

positive (presence of indole) negative (tryptophan not hydrolyzed)

Catalase test objective

detect catalase

catalase is an enzyme that

degrades H2O2

aerobic respiration H2O2 is made as _________

oxygen is reduced

H2O2 damages _____ and cell _______ and alters _______of some enzymes

DNA, membranes, active

O2 tolerant bacteria or require gas for metabolism use ________ to break down H2O2 into ________ and ______

catalase, water, O2

write out the reaction for catalase test

2H2O2 ----catalase----2H2O + O2 (gas)

Catalase test - bubbles of O2 indicate what? weak or no bubbles indicates?

positive, negative

Oxidase test objective

to determine is bacteria have cytochrom oxidase

cytochrom oxidase is a participant in what?

electron transport during respiration

What uses energ in electrons that have been removed from food molecules making force across membrane?

electron transport molecules

cytochrom oxidase is at the end point of the

eletron transport chain

cytochrom oxidase collects electrons and O2 + H+ = H2O. What is used in the absense of O2

nitrate

oxidase test - cultures need to be no more than _____ hrs old

When cytochrom oxidase adds electrons to the oxidase reagent the reduced form turns

dark blue to purple in 10 secs

Objective of motility test

to see if bacterium is motile

flagella spin like

a corkscrew

Diffuse "cloud" bacteria growing from the stab indicates?

motile

bateria growing within stab?

non-motile

motility test - what kind of agar is used instead of 1.5%

0.4 % semi solid

motility test - Incubation times

24-48 hrs up to 7days

Objective of mannitol salt agar

isolate bacteria based on their salt tolerance and identify mannitol fermentation

Mannitol salt agar is ________ because only bacteria that tolerate ________ NaCl will grow

selective, 7.5%

Salt tolerant gram-positive cocci include

Staph, mirco, entero

acid from mannitol fermentation turns indicator _________

phenol red to yellow yellow = mannitol fermentor red = mannitol non-fermentor

The addition of sugar alchol make mannitol ________

differential

MacConkey agar objective

differentiate gram-negative enteric bacilli based on ability to grow on medium and ferment lactose

MacConkey plates often used ________contaminated specimens

fecal matter

MacConkey agar is _______ because gram-positive bacteria are inhibited by crystal violet and bile salt. gram negative bacteria are unaffected

selective

MacConkey agar - lactose is added to make it ________

differential

Lactose fermentor = | Non lactose fermentor =

pink to red, colourless

MacConkey agar - incubation times

24-48hr 35c

Quiz 5 Flashcards

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