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| Frage | Antworten |
| What does natural plant cloning occur in? | Bulbs, runners, rhizomes and stem tubers |
| What are rhizomes? | A specialised horizontal stem running underground, often swollen with stored food. |
| How is natural plant cloning exploited in horticulture? | Splitting up bulbs, removing young plants from runners etc. to increase plant numbers and produce plants with the same characteristics as parent |
| What are the advantages and disadvantages of natural plant cloning? | Faster than planting seeds, guaranteed quality Lack of genetic variation - more susceptible to disease |
| What is micropropagation? | The process of making large numbers of genetically identical offspring from a single parent plant using tissue culture techniques |
| When is micropropagation used? | When the plant does not readily produce seeds, doesn't respond well to natural cloning, is rare, has been genetically modified or selectively bred with difficulty, is susceptible to pathogens |
| How are plants kept sterile outside of a sterile lab? | using sodium dichloroisocyanurate tablets |
| How is micropropagation carried out? | Take a small sample of plant tissue, sterilise by immersing in sterilising agents (bleach, ethanol, sodium dichlorisocyanurate), place the explant in a sterile culture medium containing plant hormones to stimulate mitosis, the cells proliferate forming a callus, the callus is divided up and placed into a different mixture of hormones to stimulate the development of plantlets, they are then potted and grown into crops |
| What are the advantages of micropropagation? | Rapid production of desired characteristics, disease free plants produced, reproduces genetically modified plants, produces seedless plants, a way of growing plants which are difficult to reproduce, increases numbers of rare plants. |
| What are the disadvantages of micropropagation? | Monoculture more susceptible to disease, expensive, if the source material is infected all the clones will become infected. |
| What is the main form of vertebrate cloning? | The formation of monozygotic twins - when the early embryo splits to form two separate embryos. |
| What is artificial twinning? | the process of producing monozygotic twins artificially |
| How is artificial twinning carried out in cattle? | 1) A cow with desirable traits is treated with hormones to make her super-ovulate 2) The ova are fertilised by a bull with desirable traits 3) When the cells are still totipotent, the cells are split to produce several smaller embryos 4) The embryos are implanted into surrogate mothers 5) Several identical calves are born |
| What is somatic cell nuclear transfer? | The cloning of an adult animal by transferring the nucleus of an adult somatic cell to an enucleated egg cell (oocyte) |
| How is somatic cell nuclear transfer carried out? | 1) The nucleus is removed from both a somatic cell and mature ovum from a different female 2) The nucleus from the somatic cell is placed into the enucleated ovum and given a mild electric shock so it fuses and begins to divide. 3) The embryo is transferred into the uterus of another female and develops to term The embryo will have the same DNA as the adult the somatic cell came from, but the mitochondrial DNA of the egg cell |
| What are the advantages of somatic cell nuclear transfer? | Enables GM embryos to be replicated and develop (important in pharming), allows specific animals to be cloned, rare or extinct animals can be reproduced. |
| What are the disadvantages of somatic cell nuclear transfer? | Inefficient because many eggs required to produce a single clone, rarely successful births, clones have shortened lifespans |
| What are the advantages of artificial twinning? | Produces more offspring than normal reproduction, more offspring guaranteed to have desirable traits |
| Define biotechnology | Applying biological organisms or enzymes to the synthesis, breakdown or transformation of materials in the service of people |
| Define bioremediation | The use of microorganisms to breakdown pollutants in soil and water |
| Why are microorganisms ideal for biotechnological processes? | No welfare issues, large range of microorganisms that can carry out many different functions, can be genetically engineered to carry out synthesis reactions they don't do naturally (insulin), short life cycle and rapid rate of growth, simple and relatively cheap nutrient requirements, provide their own catalysts, work at relatively low temperatures. |
| What are the disadvantages for using microorganisms in indirect food production? | Conditions ideal for other dangerous microorganisms to grow and contaminate the food so conditions have to be sterile, some microorganisms are genetically engineered which has ethical issues |
| Describe how yeast is used in baking | It is mixed with sugar and water to respire aerobically and produces carbon dioxide which makes the bread/cake rise |
| How is beer made? | 1) Malting - barley germinates producing enzymes that break starch molecules down to sugars. Seeds are then killed by slow heating but enzyme activity retained to produce malt 2) Mashing - malt is mixed with hot water (55-60 degrees) and enzymes break down starches to produces wort. Hops are added and the wort is sterilised and cooled 3) Fermentation - wort is inoculated with yeast, which respires anaerobically. Eventually the yeast is inhibited by falling pH, build up of ethanol and lack of oxygen 4) Maturation - the beer is conditioned for 29 days at temperatures of 2-6 degrees 5) Finishing - the beer is filtered, pasteurised and bottled |
| How is cheese made? | 1) Milk is pasteurised by heating it to 95degrees for 20 seconds, and homogenised to disperse fat droplets throughout the milk. 2) Bacterial cultures and sometimes chymosin enzymes are added and left unti solid curds and liquid whey 3) The curds are left to dry and mature - the bacteria continue to act. |
| How is yoghurt made? | 1) Milk is pasteurised, homogenised and cooled to about 47degrees. 2) It is then mixed with equal amounts of Lactobacillus bulgaricus and Streptococcus thermophilus and incubated |
| What fungus is Quorn made from? | Fusarium venetatum |
| What is SCP? | Single-celled protein - protein produced from microorganisms |
| What are the advantages of using microorganisms in direct food production? | Produce protein faster than animals and plants, high protein low fat, microorganisms can use a wide variety of waste materials which can reduce costs, can be genetically modified to produce specific proteins, continuous process, no welfare issues, flavours can be added |
| What are the disadvantages of using microorganisms in direct food production? | Some microorganisms can produce toxins if conditions not maintained, food is processed, needs sterile conditions which adds to cost, concerns about eating GM food, people put off by eating microorganisms, needs additives to make it taste better |
| What is the fungus that is commercially used as penicillin? | Penicillium chrysogenum |
| How is penicillin produced? | In the first stage the fungus grows and in the second stage it produces penicillin. The drug is then extracted and purified. |
| What conditions are required in the production of penicillin? | - Small fermenters are used to make it easier to maintain high levels of oxygenation - Mixture stirred continuously to keep it oxygenated - Rich nutrient medium - Growth medium contains a buffer that keeps the pH at 6.5 - Temperature of 25-27degrees |
| What are the two possible approaches to biomediation? | Using natural organisms or GM organisms |
| What are natural organisms used for in biomediation? | Breaking down organic material |
| What are GM organisms used for in biomediation? | Breaking down contaminants the microorganisms don't usually encounter eg. mercury |
| Why is it important to culture microorganisms in strictly controlled conditions? | There is always a risk of mutation making the strain pathogenic and there may be contamination from the environment |
| What is the difference between a nutrient broth and agar? | Broth is a liquid form of nutrient medium and agar is solid |
| How is broth inoculated? | 1) Make a suspension of the bacteria to be grown 2) Mix a known volume with the sterile nutrient broth 3) Stopper the flask with cotton wool to prevent contamination from the air 4) Incubate at a suitable temperature, shaking regularly to aerate the broth |
| How is agar inoculated? | 1) A wire inoculating loop is sterilised by holding it in a flame until it glows red hot. 2) The loop is dipped in the bacterial suspension and spread across the surface of the agar. 3) The lid of the agar plate is sealed with tape but not completely - so oxygen can get in. |
| Describe the growth curve of a bacterial population in a closed system | Lag phase - when bacteria are adapting to the environment, they don't reproduce but grow and synthesise enzymes they need Log/exponential growth phase - when the rate of bacterial reproduction is close to or at it's theoretical maximum. Stationary phase - when total growth rate is zero and the number of new cells forming is equal to the number of cells dying Death phase - when death rate becomes larger than rate of reproduction |
| What are the limiting factors for growth of bacteria? | Nutrients available, oxygen levels, temperature, build-up of waste, change in pH |
| Draw a graph to show the concentrations primary and secondary metabolites during the growth of a bacterial culture in a closed system | |
| What is the difference between primary and secondary metabolites? | Primary are essential metabolites of the normal functioning of a microorganism, secondary are non-essential to normal growth but are still used |
| How is batch fermentation carried out? | As growth of microorganisms in bioreactor takes place, nutrients are used up, and biomass and waste products build up. As the culture reaches stationary phase, the microorganisms often begin to form the desired end products. The process is then stopped before the death phase and products harvested. The whole system is then sterilised and a new culture started up. |
| How is continuous culture carried out? | Sterile nutrient medium is continually added to the culture once it reaches exponential growth. Culture broth is also continually removed, keeping the culture volume constant. |
| What is the process of separating a culture broth to obtain the useful part called? | Downstream processing |
| What factors are important to ensure the growing conditions in a bioreactor are at optimum? | Temperature, nutrients, oxygen, making sure the mixture is stirred continuously, sterile conditions |
| Draw and label a diagram of a bioreactor | |
| What are the advantages of isolated enzymes? | Less wasteful - no microorganisms using up substrate by growing and reproducing More efficient - enzymes can be given ideal conditions that may not be ideal for the microorganism's growth More specific - only the enzymes required present, no wasteful side reactions Less downstream processing - Pure product produced so isolating desired product less difficult |
| Why are extracellular enzymes easier to isolate than intracellular? | Extracellular are secreted, microorganisms produce relatively few extracellular enzymes making the desired enzyme easier to identify, extracellular more robust so adapted to greater changes in temperature and pH |
| What are the advantages of immobilised enzymes? | Reusable, easily separated from reaction mixture so less downstream processing, greater temperature tolerance, easily manipulated to fit a particular process |
| What are the disadvantages of using immobilised enzymes? | Less efficient as immobilising can reduce its activity rate, higher initial costs of materials and bioreactor, more complicated process |
| What are the four methods of immobilising enzymes? | Adsorption to an inorganic carrier, entrapment in a matrix, forming covalent or ionic bonds to an inorganic carrier or encapsulating in a microcapsule. |
| What are the advantages of surface immobilisation by adsorption to inorganic carriers? | Simple, inexpensive, can be used in many different processes, enzymes very accessible to substrate |
| What are the disadvantages of surface immobilisation by adsorption to inorganic carriers? | Enzymes can be lost from carrier relatively easily |
| What are the advantages of surface immobilisation by forming covalent or ionic bonds to an inorganic carrier? | Enzymes strongly bound so unlikely to be lost, enzymes very accessible to substrate, pH and substrate concentration have little effect on enzyme activity. |
| What are the disadvantages of surface immobilisation by forming covalent or ionic bonds to an inorganic carrier? | Active site may be modified in process |
| What are the advantages of entrapment in a matrix? | Can be used in many different processes |
| What are the disadvantages of entrapment in a matrix? | Expensive, difficult to entrap, slow diffusion rate to and from enzyme |
| What are the advantages of entrapment in microcapsules? | Simple, small effect on enzyme activity, can be used in many different processes. |
| What are the disadvantages of entrapment in microcapsules? | Expensive, slow diffusion rate to and from enzyme |
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