Chapter 2 - Biotechnology Flashcards
Define biotechnology
The industrial use of living organisms to produce food, drugs or other products
Explain why microorganisms are often used in biotechnology
- they grow rapidly in favourable conditions (regeneration time - time taken to double - less than 30 mins)
- can be genetically engineered to produce specific products
- grow well at low temperatures (more efficient)
- generate products that are in a more pure form than those generated by chemical processes
Describe and explain the standard growth curve of a microorganism in a closed culture
(LLSD)
- LAG PHASE:
- organisms are adjusting to the surrounding conditions The cells are active but not reproducing so population remains constant.
- depends on growing conditions
- LOG PHASE
- population size x2 each generation.
- depends on how quickly organisms reproduce and take up available nutrients/space
- STATIONARY PHASE
- nutrient levels decrease and waste products build up.
- organisms die at the same rate at which new individuals are being produced
- DECLINE PHASE
- nutrient exhaustion and increased levels of toxic waste
- death rate increases above the reproduction rate
- eventually, all organisms die
What are immobilised enzymes? What are the advantages and disadvantages to using immobilised enzymes?
Immobilised enzymes continue to catalyse the reaction but do not mix freely with the substrate.
ADVANTAGES:
- little/no purification so costs are low
- enzymes are immediately available for reuse
- more stable because the immobilising matrix protects the enzyme molecule
DISADVANTAGES
- requires additional time, equipment and materials so is more expensive to set up
- can be less active as they do not mix freely with substrate
Describe two methods of immobilising enzymes that involve binding
- ADSORPTION
- enzyme molecules are mixed with immobilising support
- they bind to it by a mixture of hydrophobic interactions and ionic links
- bonding forces are not v strong so enzymes can become detached
COVALENT BONDING
- enzyme molecules are covalently bonded to an insoluble support using a cross-linking agent like sepharose.
- doesn’t immobilise a large quantity but binding is very strong
Describe two methods of immobilising enzymes that do not involve binding
ENTRAPMENT
- enzymes may be trapped in a gel bead in their natural state.
- reaction rates are reduced because substrate molecules need to get through the trapping barrier (active site less easily available)
MEMBRANE SEPERATION
-enzymes are physically separated from the substrate mixture by a partially permeable membrane
Compare and contrast the processes of continuous culture and batch culture
BATCH CULTURE
- microorganism starter population is mixed with a specific quantity of nutrient solution
- allowed to grow for a fixed period + no further nutrient added
- at the end of the period, products are removed
CONTINUOUS CULTURE
-nutrients are added and products removed at regular intervals/continuously.
Describe the differences between primary and secondary metabolites
Primary metabolities: substances produced by an organism as part of its normal growth eg amino acids and proteins. –> matches the growth in population
Secondary metabolites: not part of normal growth eg antibiotic chemicals.–> begins after main growth period so does not match the growth in population.
ALL MICROORGANISMS PRODUCE PRIMARY METABOLITES BUT ONLY A SMALL NUMBER PRODUCE 2NDARY.
Explain the importance of essential growing conditions in a fermentation vessel in order to maximise the yield of product required
Certain growing conditions have to be controlled
1) temperature: too hot = denature, too cool = growth slowed down
2) type and time of nutrient -manipulated to produce a primary or secondary metabolite
3) oxygen conc; most are done under aerobic conditions. a lack of oxygen will lead to unwanted products of aerobic respiration
4) pH - changes in pH can reduce the activity of enzymes
Explain the importance of asepsis in the manipulation of microorganisms
Unwanted microorganisms (contaminations):
- compete with the culture microorganisms
- reduce the yield of useful products
- may produce toxic chemicals
What are the advantages and disadvantages of using batch culture?
BATCH CULTURE ADVANTAGES
- easy to set up and maintain
- if contamination occurs, only one batch is lost
- useful to produce secondary metabolites
BATCH CULTURE DISADVANTAGES
- growth rate is slower because nutrient level declines with time
- less efficient, fermenter is not in operation all of the time
What are the advantages and disadvantages of using continuous culture?
CONTINUOUS CULTURE ADVANTAGES
- growth rate is higher, nutrients are continuously added
- more efficient as fermenter operates continuously
- useful to produce primary metabolites
CONTINUOUS CULTURE DISADVANTAGES
- set up is difficult, have to maintain required growing conditions
- if contamination occurs, huge volumes of product can be lost
What are three ways of carrying out aseptic techniques at a laboratory level?
- all apparatus is sterilized before and after use by heating in a flame or by UV light
- work can be carried in a fume cupboard so it can carry away airborne microorganisms
- cultures of microorganisms are kept closed when possible using sellotape
What are three ways of carrying out aseptic techniques at large scale level?
- disinfecting the fermenter
- sterilising all nutrient media before adding to the fermenter
