Biotechnology And Gene Technologies Flashcards
What are some examples of clones in nature?
Identical twins are produced when a zygote splits in two, and are natural clones.
When plants reproduce asexually by producing runners, the new plants are clones.
When bacteria divide asexually, all the resulting bacteria are clones of the original.
What are clones?
Genes, cells or whole organisms that carry identical genetic material because they are derived from the same original DNA
What are the advantages of asexual reproduction?
- it is quick, allowing organisms to reproduce rapidly, so they can take advantage of resources in the environment
- it can also be completed if sexual reproduction fails or is not possible
- all offspring have the genetic information to allow them to survive in their environment
What are the disadvantages of asexual reproduction?
It does not produce any genetic variety, so any genetic weaknesses the parent plant has will also be in the offspring. If the environment changes, for example with the introduction of a new, disease causing organism, all genetically identical organisms will be equally susceptible.
What is vegetative propagation?
The production of structures in an organism that can grow into new individual organisms. These offspring contain the same genetic material as the parent and so are clones of the parent
How do elms carry out vegetative propagation?
They produce clones from structures called root suckers. Suckers grow from sucker buds, which are scattered around the tree’s root system. The buds are normally dormant, and are activated in times of stress. As suckers can pop up many metres away from the parent tree, they can avoid the stress that triggered their growth.
What is a root sucker?
A shoot that grows from the shallow roots of an elm tree.
What is an advantage to the elm of vegetative propagation?
Root suckers help the elm spread, because they can grow all around the original trunk. When the tree is stressed or the trunk dies, the suckers grow into a circle of new elms called a clonal patch which, in turn, puts out new suckers, so that the patch keeps expanding.
What is a disadvantage to the elm of vegetative propagation?
The elm responds to the destruction if the main trunk by growing root suckers. However if the trunk has been destroyed by disease, the suckers will also become infected and die, as if the main trunk did not have any immunity to the disease, neither will the root suckers.
What are the two main methods of artificial vegetative propagation carried out by farmers?
Taking cuttings and grafting
What is the method used by farmers of taking cuttings?
A section of the plant stem is cut between leaf joints (nodes). The cut end of the stem is then treated with plant hormones to encourage root growth, and planted. The cutting forms a new plant which is a clone of the original.
What is the method of grafting?
A shoot section of a woody plant is joined to an already growing root and stem. The graft grows and is genetically identical to the parent plant, but the rootstock is genetically different.
What method of artificial propagation can be used for large scale cloning?
Using tissue culture
Why is tissue culture better suited to large scale cloning than cuttings and grafts?
It is difficult to produce large numbers of cloned plants using either cuttings or grafts.
Some plants do not reproduce well from either of these methods.
Tissue culture can create huge numbers of genetically identical plants from a very small amount of plant material.
Tissue culture can be used to enervate large stocks of a particularly valuable plant very quickly, with the added advantage that these stocks are known to be disease free.
What is tissue culture?
The separation of cells of any tissue type and their growth in or on a nutrient medium. In plants, undifferentiated callus tissue is grown in nutrient medium containing plant hormones that stimulate development of the complete plant.
What is micropropagation?
The propagation of plants by growing them from tissue culture and then planting them.
How is micropropagation by callus tissue culture carried out?
- a small piece of tissue is taken from the plant to be cloned, usually from the shoot tip. This is called an explant.
- the explant is placed on a nutrient growth medium
- cells in the tissue divide, but do not differentiate. Instead they form a mass of undifferentiated cells called a callus.
- after a few weeks, single callus cells can be removed from the mass and placed on a growing medium that contains plant hormones to encourage shoot growth.
- after a further few weeks the growing shoots are transferred to a growing medium that contains the hormones to encourage root growth.
- the growing plants are then taken to a greenhouse for further growth before they are planted outside.
What are the advantages of plant cloning in agriculture?
Farmers know what the crop plant will be like as it is cloned from a plant with known, desirable characteristics.
Farmers costs will also be reduced as all the crop will be ready for harvest at the same time.
What are disadvantages of using cloned plants in agriculture?
All plants will be equally susceptible to new pests, diseases or environmental changes, so the entire crop could be wiped out by one of these things.
What precautions are taken to stop disease from destroying genetically identical crops?
Farming methods are regulated so that the area of land given to a certain genetically uniform crop is limited, and the distance between areas of the same crop is also controlled, to limit the effects and spread of new pathogens.
What are the two methods of artificial cloning used in animals?
Splitting embryos, to form artificial identical twins.
Nuclear transfer, using enucleated eggs.
What cells in animals can be used for cloning?
Only embryonic cells, as these are totipotent stem cells (they can differentiate into any type of adult cell found in the organism)
What is the method used for cloning animals by nuclear transfer?
A differentiated cell from an adult can be taken, and it’s nucleus placed in an egg cell, which has had it’s own nucleus removed. The egg cell is stimulated to divide and then goes through the stages of development using genetic information from the inserted nucleus.
What are the advantages of artificially cloning animals?
- Desirable genetic characteristics are always passed on to clones - this doesn’t always happen with sexual reproduction due to variation
- high value animals can be cloned in large numbers
- rare animals can be cloned to preserve the species
- infertile animals can be reproduced
- genetically modified animals can be quickly reproduced
- animals can be cloned at any time, not just in breeding seasons.
What are the disadvantages of artificially cloning animals?
- undesirable traits are always passed on, as well as desirable ones.
- as with plants, excessive genetic uniformity in a species makes it unlikely to be able to cope with, or adapt to, changes in the environment.
- reproductive cloning is also very difficult, time consuming and expensive.
- it is unclear whether animals cloned using the nuclear material of adult cells will remain healthy in the long term.
What is non-reproductive cloning?
The cloning of cells to generate tissues and organs to replace those damaged by diseases or accidents, rather than to create entire new organisms.
What are the advantages of non-reproductive cloning?
- it can be used to create tissues and organs that are genetically identical to the individual’s own cells, meaning they will not be ‘rejected’ as the immune system will not recognise them as foreign.
- cloning and cell culture techniques could mean an end to the current problem of waiting for donor organs to become available for transplant.
- cloned cells can be used to create any type of cell as they are totipotent, meaning they could repair damage caused by some diseases and accidents that is not currently treatable.
What are the possibilities for future uses of non-reproductive cloning?
- to regenerate heart muscle cells after a heart attack
- to repair nervous tissue damaged by diseases like multiple sclerosis
- to repair the spinal cords of those paralysed by accidents resulting in broken backs or necks
What is the method used for non-reproductive cloning?
Embryos are created, possibly by cloning a patient in need of a transplant, and embryonic stem cells are harvested from them. These stem cells have the potential to become any cell type in an organism, so they can be made into any type of tissue or organ required by the patient.
What is a disadvantage to non-reproductive cloning?
There are ethical objections to the use of human embryonic material.
Scientific concerns about a lack of understanding of how cloned cells will behave over time.
What is biotechnology?
The industrial use of living organisms to produce food, drugs and other products.
What are the four main areas in which biotechnology has applications?
- healthcare and medical processes - this includes the production of drugs by microorganisms and gene therapy to treat some genetic disorders.
- agriculture - this includes micropropagation of plants and the development of genetically modified plants.
- industry - this includes genetically modifying organisms to produce enzymes
- food science - this includes developing foods with improved nutrition, or better taste, texture and appearance.
What type of organisms are most commonly used in biotechnology?
Microorganisms such as bacteria and fungi
Why are microorganisms commonly used in biotechnological processes?
- their ideal growth conditions can be easily created
- they grow rapidly under the right conditions, so products can be made quickly
- they can be grown on a range of inexpensive materials
- they can be grown at any time of year and anywhere in the world, as they are not dependent on climate
- tend to generate products in a more pure form than those generated via chemical processes
- they can be genetically engineered to produce specific products
What does the standard growth curve apply to?
The population growth of a small number of organisms placed in a fresh ‘closed culture’ environment.
What is a closed culture?
A growth of microorganisms in an environment where all conditions are fixed and contained. No new materials are added and no waste products or organisms removed.
What are the stages of a standard growth curve?
The lag phase
The log (exponential growth) phase
The stationary phase
The decline/death phase
What happens in the lag phase of the standard growth curve?
Organisms are adjusting to the surrounding conditions. This may mean taking in water, cell expansion, activating specific genes and synthesising specific enzymes. The cells are active but not reproducing so population remains fairly constant.
What happens during the log (exponential growth) phase of the standard growth curve?
The population size doubles each generation, as every individual has enough space and nutrients to reproduce.
What happens during the stationary phase of the standard growth curve?
Nutrient levels decrease and waste products, like carbon dioxide and other metabolites, build up. Individual organisms die at the same rate at which new individuals are being produced, and there is competition for resources. This means the population size stays level.
What happens during the decline/death phase of the standard growth curve?
Nutrient supplies are exhausted and waste products build up to toxic levels. This leads to the death rate rising above the reproduction rate. Eventually all organisms will die in a closed system.
What does fermentation refer to?
The culturing of microorganisms, both aerobically and anaerobically, in fermentation tanks to produce useful products.
What is a metabolite?
A substance that is formed during a metabolic reaction
What are primary metabolites?
Substances produced by an organism as part of its normal growth; they include amino acids, proteins, enzymes, nucleic acids, ethanol and lactate. Microorganisms produce primary metabolites at all stages of the standard growth curve, as they are essential for the growth of the microorganism.
What are secondary metabolites?
Substances produced by an organism that are not part of its normal growth. They are not essential for the growth of microorganisms, however they are useful in other ways, such as to kill other types of microorganisms, reducing interspecific competiton. Secondary metabolites are only produced when growing conditions are less favourable (e.g. during the stationary phase of the standard growth curve)
What phases of the standard growth curve are primary metabolites produced in?
All phases, but primarily the lag and exponential phases
What phases of the standard growth curve are secondary metabolites produced in?
The stationary and decline phases, as they are produced when organisms start to compete for resources.
What is an industrial scale fermenter?
A huge tank, in which the growing conditions can be manipulated and controlled, to ensure the best possible yield of the product
What conditions inside a fermentation vessel need to be controlled and how is this done?
- pH is monitored by a probe and kept at the optimum level to increase production yield by allowing enzymes to work efficiently, so that the rate of reaction is as high as possible
- temperature is kept at the optimum level by a water jacket surrounding the vessel, allowing enzymes to work efficiently and increasing product yield
- the oxygen supply is kept at the optimum level by pumping in sterile air when needed. This increases the product yield as it ensures microorganisms can always respire to produce energy for growth.
- microorganisms are kept in contact with fresh medium by paddles that circulate the medium around the vessel. This increases product yield, as microorganisms always have access to nutrients for growth.
How do you ensure the fermentation vessel is free from contamination?
All nutrients and gasses which enter the vessel are sterilised, and the vessel is sterilised between uses with superheated steam, to kill any unwanted organisms and make sure the next culture is not contaminated. This increases the product yield as it ensures that microorganisms aren’t competing with other organisms.
How is temperature controlled in a fermentation vessel?
Using a water jacket surrounding the vessel
What are the two main culture methods?
Batch culture, where microorganisms are grown in individual batches in a fermenter and then removed and replaced by a new batch.
Continuous culture, where microorganisms are continually grown in a fermentation vessel without stopping.
What are the characteristics of batch cultures?
- a fixed volume of nutrients is added to the fermentation vessel at the start of the culture and no more is added. The culture is a closed system.
- each culture goes through the lag, exponential and stationary growth phases.
- the product is harvested once, during the stationary phase.
- the product yield is relatively low, as product is not being continuously produced because the reaction is stopped and the vessel sterilised between batches.
- if contamination occurs it will affect only one batch, meaning it does not have a huge affect, and won’t waste that much money.
- batch culture is used to produce secondary metabolites.
What are the characteristics of continuous culture?
- growth medium flows through the vessel at a steady rate so there’s a constant supply of fresh nutrients. The culture is an open system.
- the culture goes through the lag phase but is then kept at the exponential phase and does not progress to the stationary or decline phases.
- the product is continuously taken out of the fermentation vessel at a steady rate
- the product yield is relatively high - microorganisms are constantly growing at an exponential rate.
- if the culture is contaminated the whole lot has to be discarded, which is very expensive when cultures are done on an industrial scale.
- continuous culture is usually used when you want primary metabolites or the microorganisms themselves are the desired products.
What method of culture - batch or continuous - would you use to produce secondary metabolites?
Batch culture
Which method of culture, batch or continuous, would be more expensive to deal with if it became contaminated?
Continuous, as the whole culture must be thrown away, rather than just one batch
Which method of culture, batch or continuous, has a higher product yield?
Continuous culture, as microorganisms are constantly growing at an exponential rate, and the product is continuously being produced and harvested, whereas in batch culture, there is a period when no culture is being produced, and production is constantly being stopped and restarted.
What is asepsis?
The absence of unwanted microorganisms
Why is asepsis important in the biotechnology industry?
Because contamination can affect the growth of the microorganism you’re interested in. Unwanted microorganisms may:
•compete with culture microorganisms for space and nutrients
•reduce the yield of useful products from culture microorganisms
•cause spoilage of products
•produce toxic chemicals
•destroy the culture microorganism and their products.
What does the term ‘aseptic technique’ refer to?
any measure taken at any point in a biotechnological process to ensure that unwanted microorganisms do not contaminate the culture that is being grown, or the products that are extracted.
