Cloning and biotechnology chp 22 ONLY DONE 22.6 + .8 Flashcards
why should you take care when culturing microorganisms
- risk of mutation making bacteria pathogenic
- may be contamination with pathogenic microorganisms from environment
define inoculation
- adding of bacteria to nutrient medium (agar or broth)
explain steps to inoculate broth
- make suspension of bacteria to be grown
- mix known vol of bacteria with sterile nutrient broth
- stopper flask with cotton wool to prevent contamination
- incubate at suitable temperature
^shake regularly to aerate broth and provide bacteria with oxygen
explain steps to inoculating agar
- use sterile inoculating loop (Bunsen burner, until glow red hot)
^don’t let it touch surface to avoid contamination - dip loop in bacteria suspension
- remove lid of Petri dish
- apply in zig zag pattern (gently)
- replace lid of dish
- secure lid with tape and store upside down to avoid condensation dripping
- incubate
what’s the 1st phase of growth of bacterial colonies
- lag phase
^growing,
^synthesising enzymes
^not producing at max rate
what’s the 2nd phase of growth of bacterial colonies
- log/exponential phase
^rate of reproduction at max
whats the 3rd phase of growth of bacterial colonies
features of
- stationary phase
^total growth rate = 0
^number of cells made from binary fission = number of cells dying
what’s the last phase of growth of bacterial colonies
- death stage
^reproduction almost ceased
^death rates of cells increasing
what are some limiting factors to growth of bacteria
- nutrients available
- oxygen levels
- temperature (can denature)
- build up of waste (raises toxicity of environment)
- change in pH (can denature)
what are some examples of aseptic techniques
- closing doors + windows + turning off fans
- roll up sleeves, take jewelry off, tie up hair
- sanitise surface with 70% alcohol
- wash hands and forearms
- steralise all equipment before and after
- once equipment picked up don’t put it down until finished with
- open bottles with pinky
- flaming (bottle necks, inoculating loops)
- keep lid on petri dish for as long as possible (if opening keep close to dish)
- incubate agar unside down
define isolated enzymes
Enzymes separated from their natural environment
what are some advantages of using isolated enzymes instead of whole organisms
- less wasteful
- more efficient
- more specific (no unwanted enzymes present)
- maximises efficiency (can give optimum conditions for that enzyme)
- less downstream processing (pure product formed so no need to purify)
what type of enzymes are isolated enzymes usually
- extra cellular
why are extracellular enzymes easier to form into isolated enzymes
- are secreted making them easier to isolate
- organisms produce relatively few extracellular enzymes so easy to identify
- tend to be much more robust
when would intracellular enzymes be used as isolated enzymes
- bigger range of intracellular enzymes
^so can be more specific
^in this case pros > cons
