Cloning and biotechnology Flashcards
What is cloning
The process of producing genetically identical cells or organisms from the cells of an existing organism. It can occur naturally in some plants and animals, but it can also be carried out artificially
What is vegative propagation
The production of plant clones from non-reproductive tissues such as roots, leaves and stems
What are the natural vegative propagation methods plants use (8)
Rhizomes
Stolons (runners)
Tubers
Bulbs
Cuttings
Grafting
Layering
What are rhizomes and an example
Stem structures that grow horizontally underground away from the parent plant. They have ‘nodes’ from which new shoots and roots can develop.
E.g Bamboo
What are Stolons (runners) and an example
Quite similar to rhizomes but can grow above the ground on the surface the soil. New shoots and roots can either develop from nodes or form at the end of the stolon
E.g Strawberries
What are suckers and an example
Are shoots that grow from sucker buds present on the shallow roots of parent plant
E.g Elm trees
What are tubers and an example
Large underground plant structures that act as a food store for the plant. They’re covered in ‘eyes’. Each eye is able to sprout and form a new plant
E.g potatoes
What are bulbs and an example
Underground food stores used by some plants. New bulbs are able to develop from the original bulb and form new individual plants.
What is grafting
Joining the shoot of one plant to the growing stem and root of another plant
What is layering
Bending a stem of a growing plant downwards so it enters the soil and grows into a new plant
How do you produce a clone from a cutting
1) Use a scalpel or sharp secateurs to take a cutting between 5 and 10 cm long from the end of a stem of your parent plant
2) Remove the leaves from the lower end of your cutting leaving just one at the tip
3) Dip the lower end of the cutting in rooting powder, which contains hormones inducing root formation
4) Plant your cutting in a pot containing a suitable growth medium
5) Provide the cutting with a warm and moist environment by either covering the whole pot or putting it in a propagator
6) When the cutting has formed its own roots it can be planted elsewhere
What are the two types of plant cuttings and how do they work
Root cutting - cut a piece of root from the plant with a straight cut using a scalpal removing the uncut end of the root with a slanted cut. Dip the end in rooting powder and plant it in a growth medium
Split vein cutting - removing a complete leaf and scoring the large veins on the lower leaf surface using a scalpal. Put it on top of a growth medium with the broken veins facing down. A new plant should form from each break in the veins
How can plants be artificially cloned using tissue culture/micropropagation
1) Cells are taken from the original plant that’s going to be cloned
2) Cells from the stem and root tips are sued because they’re stem cells - like in humans, plant stem cells can develop into any type of cell
3) The cells are sterilised to kill any microorganisms such as bacteria and fungi that compete for nutrients with the plant cells
4) The cells are placed on a growth medium contains plant nutrients such as glucose and growth hormones such as auxins
5) When the cells have divided and grown into a small plant they’re taken out of the medium and planted in soil to develop into plants
What is the difference between tissue culture and micropropagation
Tissue culture is used to clone plants that don’t readily reproduce, are endangered or rare or grow whole plants from genetically engineered plant cells
Micropropagation is when tissue culture is used to produce lots of cloned plants very quickly
What are the arguments for artificial plant cloning
- Desirable genetic characteristics are always passed on to clones. This doesn’t always happen when plants reproduce sexually
- Tissue culture allows plants to be reproduced in any season
- Less space is required by tissue culture than would be needed to produce the same number of plants by conventional growing methods
- It produces lots of plants quickly compared to the time it would take to grow them from seeds
What are the arguments against artificial plant cloning
- Undesirable genetic characteristics are passed on to clones
- Cloned plant populations have no genetic variability so a single disease could kill them all
- Production costs of tissue culture are very high due to high energy use and the training of skilled workers so it’s unsuitable for small scale production
- Contamination by microorganism during tissue culture can be disastrous and result in complete loss of the plants being cultured
How can animal clones occur naturally
During sexual reproduction once an egg has been fertilized it can be split during development into multiple embryos, known as twins
What are the two methods of producing animals by artificial cloning
- Artificial embryo twinning
- Somatic Cell Nuclear Transfer (SCNT)
Process of artificial embryo twinning
1) An egg cell is extracted from a female cow and fertilized in a Petri dish
2) The fertilised egg is left to divide at least once forming an embryo
3) The individual cells from the embryo are separated and each is put into a separate Petri dish. Each cell divides and develops normally, so an embryo forms in each Petri dish
4) The embryos are then implanted into female cows, which act as surrogate mothers
5) The embryos continue to develop inside the surrogate cows, and eventually the offspring are born. They’re all genetically identical to each other
Process of somatic cell nuclear transfer
1) A somatic cell is taken from sheep A and the nucleus is extracted and kept
2) An oocyte is taken from sheep B, it’s nucleus is removed to form an enucleated oocyte
3) The nucleus from sheep A is inserted into the enucleated oocyte from sheep B
4) The nucleus and the enucleated oocyte are fused together and stimulated to divide by electrofusion
5) This produces an embryo which is implanted into a surrogate mother and then a lamb is then born as a clone of sheep A
What is a somatic cell
Any cell that isn’t a reproductive cell
What is an oocyte
Immature egg cell
What are the uses of animal cloning (5)
- Research purposes
- Save endangered animals
- Agriculture
- Producing useful substances
- Make Embryonic stem cells
How can research purposes be a use of animal cloning
Can be used to test new drugs on cloned animals as they are genetically identical
How can animal cloning be used for saving endangered animals
Prevent them from extinction by cloning new individuals
How can animal cloning be used in agriculture
Farmers are able to increase the number of animals with desirable characteristics to breed from
How can animal cloning be used to produce useful substances
Genetically modified animals produce substances that may not normally be produced such as a protein in their milk which could be cloned to produce lots more identical animals
How can animal cloning be used to make embryonic stem cells
The cells are harvested from young embryo’s and have the potential to become any cell type. Could be used to replace damaged brain tissues in a range of diseases. If it is genetically identical then it will not be rejected
Arguments for animal cloning
- Desirable genetic characteristics are always passed on to clones unlike sexual reproduction
- Infertile animals can be reproduced
- Increasing the population of endangered species helps to preserve biodiversity
- Animals can be cloned at any time and do not have to wait until breeding season
- Cloning can help develop new treatments for disease = less suffering
Arguments against animal cloning
- It is very difficult, time-consuming and expensive
- There is no genetic variability so undesirable characteristics are always passed on to clones, meaning all the cloned animals are susceptible to the same diseases possibly wiping them out
- Some evidence suggests clones do not live as long - unethical
- Using clones human embryos is controversial as they are usually destroyed after the embryonic stem cells have been harvested
What is biotechnology
The industrial use of living organisms to produce food, drugs and other products. They mostly use microorganisms (bacteria and fungi) as the living organisms
Why are microorganisms (bacteria and fungi) mostly used in biotechnology
- Their ideal growth conditions can easily be created (right nutrients, temperature, pH, moisture levels, availability of gases
- They have a short life cycle so grow rapidly under the right conditions so products can be made quickly
- Can be grown on a range of inexpensive materials
- Can be grown at any time of the year
Examples of some industrial processes microorganisms are used for
Brewing beer, making cheese and yoghurt, penicillin and insulin production
What are the advantages of producing food for consumption using microorganisms
- Can make single-cell protein that could actually be used as a way of getting rid of waste products
- They can be grown quickly, easily and cheaply due to simple growth requirements as can be grown on waste products and less land is required
- Can be cultured anywhere if you have the right equipment meaning a food source can be readily produced unlike using livestock
- Single-cell protein is considered healthier than animal protein
What are the disadvantages of producing food for consumption using microorganisms
- The conditions needed to grow the desired microorganism are also ideal for other microorganisms as a lot of effort has to go into making sure the food does not get contaminated with unwanted bacteria that would spoil the food
- People may not like the idea of eating food that has been grown using waste products
- Single-cell protein doesn’t have the same texture or flavour as real meat
- If single-cell protein is consumed in high quantities, health problems could be caused due to the high levels of uric acid released when the large amounts of amino acids are broken down
What is a culture of microorganisms
A population of one type of microorganism that’s been grown under controlled conditions
How are cultures grown
In large containers called fermentation vessels to either obtain lots of the microorganism or to collect useful products the microorganism makes
What are the two methods of culturing microorganisms
Batch and continuous
What is batch fermentation
Where microorganisms are grown in individual batches in a fermentation vessel - where one culture ends it is removed and then a different batch is grown in the vessel.
What is continuous fermentation
Where microorganisms are continually grown in fermentation vessel without stopping. Nutrients are put in and waste products are taken out at a constant rate
What factors are constantly being monitored during fermentation
pH, temperature, access to nutrients, volume of oxygen, vessel kept sterile
How is pH regulated and how does that maximise yield
Constantly monitored by a pH probe and kept at the optimum
Allowing enzymes to work efficiently so the rate of reaction is kept as high as possible
How is temperature regulated and how does that maximise yield
Kept constant by a water jacket that surrounds the entire vessel
Allowing enzymes to work efficiently so the rate of reaction is kept as high as possible
How is access to nutrients regulated and how does that maximise yield
Paddles constantly circulate fresh nutrient medium around the vessel
Ensuring that microorganisms always have access to their required nutrients
How is the volume of oxygen regulated and how does that maximise yield
Sterile air is pumped into the vessel when needed
Makes sure that the microorganisms always have oxygen for respiration
How is the vessel being kept sterile regulated and how does that maximise yield
Superheated steam sterilises the vessel after each use
Kills any unwanted organisms that may compete with the ones being cultured
What is a closed culture
When growth takes place in a vessel that’s isolated from the external environment. Extra nutrients aren’t added and waste products are not removed. This then follows the standard growth curve and an example could be such as batch fermentation
What are the four stages in order of the standard growth curve
1) Lag
2) Exponential/log
3) Stationary
4) Death
What stage is the lag phase and what happens
The first stage where the population size increases slowly because the microorganisms have to make enzymes and other molecules before they can reproduce. This means the reproduction rate is low
What stage is the exponential/log phase and what happens
The population size increases quickly because the culture conditions are at their most favourable for reproduction. The number of microorganisms doubles at regular intervals
What stage is the stationary phase and what happens
The population size stays the same because the death rate is equal to the reproductive rate. Microorganisms die becuase there is not enough food and poisonous waste products build up
What stage is the death phase and what happens
The population size falls becuase the death rate is greater than the reproductive rate. This is becuase food is very scarce and waste products are at toxic levels
During the exponential/log phase how quick is growth
The number of cells in a culture of microorganism doubles at regular intervals.
How can you calculate the number of individuals that are present in a population
After a certain number of divisions you can use number of individuals present in population=initial number of cells x 2^number of divisions .
How to culture microorganisms in the lab
1) Transfer microorganisms to an agar plate using a sterile implement such as inoculation loop or sterile pipette and spreader
2) Then incubate the plates allowing microorganisms to grow
3) Nutrients can be added to the agar to help improve the growing conditions
Why are aseptic techniques used
To prevent contamination of cultures by unwanted microorganisms, which may affect the growth of the microorganism being cultured. Contaminated cultures in laboratory experiments give imprecise results and may be hazardous to health. Also it can be very cultures as it destroys entire cultures
What are the aseptic techniques that should be followed in a lab
- Regularly disinfect surfaces
- Work near a Bunsen flame as it draws away the microorganisms
- Sterilise the instrument used to transfer cultures such as passing inoculation loop through flame
- Minimise time agar plate is open
- Sterilise all glassware before and after use e.g autoclave
- Wear a lab coat, gloves and tie long hair back
How to measure the effects on the growth of bacteria (can be applied to other microorganisms e.g fungi)
1) Use a sterile pipette to add a set volume of bacteria sample to an agar plate
2) Spread the broth across the surface using a sterile spreader
3) Put the lid on and tape lightly
4) Repeat until there are 6 plates
5) Place 3 plates in a fridge at 4 degrees C and the other 3 in an incubator (or at room temp) at 25 degrees C. They should be incubated upside down to prevent condensation forming on the lid
6) Put another lidded agar plate in each of the two temperature locations that is uncultured acting as negative controls
7) Leave all plates for same time period e.g 48 hours
8) If bacterial growth has occured colonies should be seen that you can count and work out the mean at each temperature
What is a Spectrophotometer
A machine that measures the turbidity of the broth - a higher turbidity means more cells are present and more replication has occured
What are intracellular enzymes
Enzymes that are contained within cells
What are isolated enzymes
Enzymes that aren’t contained within cells. Some are naturally secreted (extracellular enzymes) but others have to be extracted which is more expensive
What are the three ways that enzymes are immobilized
- Encapsulated in jelly-like alginate beads, which act as a semi-permeable membrane
- Trapped in a silica gel matrix
- Covalently bonded to cellulose or collagen fibres
Why are immobilized enzymes used in industry
As it means the enzyme can be reused in future processes rather than being discarded after it has been used once
How are immobilized enzymes used in industry
The substrate solution for a reaction is run through a column of immobilized enzymes. The active sites of the enzymes are still available to catalyze the reaction but the solution flowing out of the column will only contain the desired product
Advantages of using immobilised enzymes in industry
- Columns can be washed and reused to reduce the cost of running a reaction on an industrial scale as you don’t have to keep buying new enzymes
- The product isn’t mixed with the enzymes - no money or time is spent separating them out
- Immobilised enzymes are more stable than free enzymes -they’re less likely to denature in high temperatures or extreme pH
Disadvantages of using immobilised enzymes in industry
- Extra equipment is required, which can be expensive
- Immobilised enzymes are more expensive to buy than free enzymes and so coupled with the equipment costs, they’re not always economical for use in smaller-scale production
- The immobilisation of the enzymes can sometimes lead to a reduction in the enzyme activity because they can’t freely mix with their substrate
