What does the term 'to culture'? mean in terms of microorganisms?
To culture microorganisms means to grow the MO's on a large scale and so they grow into cultures that can be seen with the naked eye
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What are the 2 health and safety points to be taken into consideration when culturing MO's?
There is always a risk of mutation taking place which could make the strain pathogenic, there may be contamination with pathogenic MO's
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When culturing MO's, what is needed?
A good supply of food (nutrients from broth or agar), the right temperature, PH and a rich oxygen supply
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What are aseptic techniques?
Techniques used to prevent contamination
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What is inoculation?
A process of adding the bacteria to the broth or agar
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Inoculating broth
Suspend bacteria to be grown and mix of know quantity with sterile nutrient broth, stopper the flask with cotton wool to prevent contamination but to allow oxygen in and incubate at suitable temperature, shaking regularly
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Inoculating agar
Wire loop sterilised by burning till red hot, not allowing it to touch any other surfaces to keep sterile, sip sterile loop into bacterial suspension and wipes onto surface of agar, avoid loop from digging into agar, seal but not fully and incubate
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Bacteria reproduce rapidly, what are the 4 stages of the growth curve?
Lag phase, exponential/log phase, stationary phase and death/decline phase
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Lag phase
When the bacteria are adapting to environment and producing enzymes they need, not yet reproducing at maximum rate
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Exponential/log phase
When the reproduction rate is at its theoretical maximum
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Stationary phase
When the rate of reproduction and the death rate is the same so the total growth rate is 0
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Decline/death phase
When when reproduction has almost ceased and the death rate of cells is increasing
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Name some limiting factors
Nutrients available, Oxygen levels (to aerobically respire), temperature and ph (enzymes, ph builds up due to CO2), buildup of waste (inhibits further growth and can even poison cells)
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Other cards in this set
Card 2
Front
What are the 2 health and safety points to be taken into consideration when culturing MO's?
Back
There is always a risk of mutation taking place which could make the strain pathogenic, there may be contamination with pathogenic MO's
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