biotechnology Flashcards
what is the definition of biotechnology?
the use of living organisms in industrial processes to produce food/drugs through genetic modification, cloning, and selective breeding.
describe 5 reasons why micro-organisms are used in biotechnological processes
- less ethical issues than keeping livestock.
- short life cycles so large populations can be grown very quickly in reaction vessel.
- requires lower temps so cheaper product and saves fuel emissions.
- NOT climate dependant and so processes can take place anywhere in the world.
- can be used in genetic engineering to produce human insulin.
explain the function cold-water inlet and why it is useful in an industrial fermenter
allows circulation of water around the fermenter to regulate temperature. If a product is allowed to build up, it may affect synthesis of a product.
explain the function sterile nutrient medium and why it is useful in an industrial fermenter
provides oxygen in aerobic fermenters - it allows micro-organisms to respire and allow synthesis of product. It is a source of carbon, nitrogen, minerals and vitamins.
explain the function pH and temp probe and why it is useful in an industrial fermenter
keeps temp and ph in narrow range to prevent denaturing of enzyme/inactivity of enzyme if too cold.
what must be done to the antifoam in the industrial fermenter
sterilise fermenter to reduce foam clumping as pipe could have contaminating bacteria, which reduces competitive exclusion
name a primary metabolite
ethanol
name a secondary metabolite
penicillin
what is the function of ethanol
used in continuous fermentation
provides optimum conditions for growth.
describe continuous fermentation
microorganism are inoculated into sterile medium and start to grow.
sterile nutrient medium is continuously added to the culture once it reaches the exponential point of growth.
culture broth is continuously removed so culture volume in fermenter is constant.
describe batch fermentation
closed culture - limited nutrients available in stationary phase.
microorganism are inoculated into a fixed vol of sterile medium.
as growth takes place, nutrients are used up and both new biomass and waste products build up.
as culture reaches stationary phase overall growth stops but the microorganism often produce the desired end product as secondary metabolites.
process stopped before death phase and products harvested and new batch started up. e.g. yoghurt, cheese.
when is penicillin made?
in times of stress! - when microorganism growth slows at stationary phase
culture difference between batch and continuous
batch = closed culture
continuous = open culture
what phase is batch fermentation in
stationary phase
what phase is continuous fermentation in?
exponential phase
difference between batch and continuous in terms of inoculation
batch = inoculated in fixed volume of sterile medium
cont. = nutrient continuously added once it reaches exponential growth.
in batch fermentation, exponential growth is…
short - slower growth rates due to limiting factors.
in continuous fermentation, exponential phase is…
long - fast growth is maintained.
examples of batch fermentation
wine, beer, yoghurt, cheese
examples of continuous fermention
quorn, mycoprotein, human insulin
what is the difficulty with continuous fermentation?
can be difficult to maintain conditions so that exponential phase is maintained. Foaming, clumping + blocked inlets are increased.
describe 3 advantages of using mycoprotein to produce food for human consumption.
- healthier alternative to meat protein because it has less fat, lowering risk of heart disease.
- reproduces fast so production of proteins is much faster than that of animal protein.
- not much land required and no animal welfare issues.
describe 3 disadvantages of using mycoprotein to produce food for human insulin.
- if mycoprotein consumed in large quantities, high uric acid levels can be caused when amino acids broken down.
- increase risk in infection as conditions are ideal for pathogenic microorganisms.
- mycoprotein does not have same taste/texture of traditional protein sources + less iron so risk of anaemia
why must the bottle of a neck be placed over a flame?
causes air to move out of bottle = decreasing likelihood of contamination.
why is having a bunsen burner burning nearby a practical a useful aseptic technique?
convection currents cause hot air to rise => prevents airborne microorganisms from settling and so creates work area of sterile area.
how to sterilise inoculating loop?
sterilised by holding in a bunsen burner flame until it glows red hot from base to tip = kills microorganisms
how can equipment be sterilised?
dip in ethanol and flame it to sterilise
why should you not lift a petri dish lid off completely?
reduce chance of microorganism getting onto the agar
why should tape not be sealed all around the agar plate?
allows plate to be aerobic = oxygen can’t get in and prevents anaerobic bacteria growing.
why must the agar plate be turned upside down?
to prevent the accumulation of water condensation that could disturb a culture.
how do you ensure measurements of a cell count in a liquid culture?
- plates with more than 300 colonies or less than 30 colonies should be disregarded.
- plates with too many colonies lead to inaccuracy.
- Plates with small numbers have greater margins of error as small changes in number counted will lead to big changes in estimate.
describe the steps in making a serial dilution
- stir test tube with sample taken from fermenter.
- use pipette to take 1cm3 of sample, and add to 9cm3 of water into a test tube.
- stir to mix sample with water.
- take 1cm3 from that test tube and add to another test tube filled with 9cm3 to increase the dilution factor by 10.
when observing the spread plate before counting colonies. How can you be confident that all colonies you see are from the original broth?
- check colour
- check morphology of colonies
what is the definition of an immobilised enzyme?
an enzyme that is held in place and not free to diffuse through a reaction mixture.
what factors must you consider when writing out a practical investigation?
- independent variable
- dependant variable
- HOW you are going to carry out investigation
- control variables (probes, conc, same species)
- repeats
- control experiment e.g. (no bacteria nutrient broth as baseline compare)
- safety precautions/aseptic techniques
describe adsorption as a method of immobilisation
enzyme bound to supporting surface by a combination of hydrophobic and iconic links e.g. glass beads
name 4 methods to immobilise enzymes
- adsorption
- surface immobilisation
- entrapment
- membrane encapsulation
describe surface immobilisation
enzymes are bonded to supporting surface such as clay using covalent or ionic bonds. Enzymes are bonded using a cross-linking agent.
describe entrapment as a method of enzyme immobilisation
enzymes are trapped in a matrix e.g. polysaccharides (cellulose mesh) that does not allow free movement.
describe membrane encapsulation as a method of enzyme immobilisation
encapsulation in microcapsules made of semi-permeable membrane (membrane separation)
describe alginate beads as a form of enzyme immobilisation for lactase to provide lactose free milk
- lactase mixed with solution of sodium alginate.
- little droplets added to solution of calcium chloride instantly reacting to form jelly.
- enzyme held in bead and therefore immobilised.
- milk containing lactase’s’ substrate is trickled over beads.
- enzyme in beads catalyse reaction that converts lactose into glucose and galactose without being mixed freely with the substrate.
- Therefore, lactose free milk is produced.
advantages of using immobilised enzymes
- enzymes do not mixed with product, so extraction costs are lower.
- enzymes can easily re-used and are unaffected.
- simple and cheap.
- enzymes are surrounded by the immobilising matrix which protects them from extreme conditions - so higher temps or a wider pH range can be used without denaturing.
disadvantages of using immobilised enzymes.
- requires time, materials, specialist training,
- enzymes can be less active because they don’t mix freely with substrate and have less access to active site so less ESCs formed.
- contamination means the whole system would need to be stopped and so it’s expensive to deal with.
name the 4 stages of the bacterial growth curve
- lag phase
- log phase
- stationary phase
- death phase
lag phase (1)
- slow cell division/reproduction
- genes switching on
- synthesis of enzymes
log phase (2)
- less limiting factors, rate of bacterial cell division increases = exponential growth = population doubles each unit of time (therefore increasing bacteria population)
stationary phase (3)
- rate of cell division decreases due to limiting factors = no. of bacteria produced is equivalent to no. of bacteria dying.
- there is more competition due to lack of nutrients/O2/glucose/build up of wastes => approaching carrying capacity.
death phase (4)
no. of cells dying is greater than the number of cells formed = this is due to lack of nutrients, build up of wastes, greater competition so therefore bacterial population decreases.
compare the equipment and techniques of taking cuttings with those used for micropropagation
micropropagation is more expensive, requires more skills and strict aseptic conditions.
Cutting produces less clone offsprings but is cheaper.
Describe how to clone a plant by taking a cutting.
- use a healthy shoot
- cut stem at a slant
- dip in hormone auxin
- add water (to reduce transpiration)
- cover with plastic bag
- remove leaves
