where can new plants propagate from
Where does natural plant cloning / vegetative propogation occur?
Bulbs - leaf bases swell with stored food from photosynthesis. Buds form internally which develop into new shoots.
Runners - a lateral stem grows away from the parent plant and roots develop where the runners hit the ground.
Rhizomes - a specialised horizontal stem running underground, often swollen with stored food. Buds develop and form new vertical shoots which become independent plants.
Stem tubers - the tip of an underground stem becomes swollen with stored food to form a tuber or storage organ. Buds develop to produce new shoots.
What are the advantages and disadvantages of using cuttings
faster than using seeds
guarantees quality of the plant
offspring are genetically identical
lack of genetic variation - disease or climate change could wipe them all out
How do you produce a clone from a cutting
1) Use a scalpel to cut a piece of stem from the parent plants between 5 and 10 cm.
2) Remove the leaves from the lower end of your cutting, leaving one at the tip.
3) Dip the lower end of the cutting in rooting powder, which contains hormones that induce root formation.
4) Then plants your cutting in a pot containing well-drained compost.
5) Provide your cutting with a warm and moist environment by covering in a plastic bag or putting in propagator.
6) When your cutting has formed its own roots and is strong enough, plant it elsewhere to continue growing.
the process of making large numbers of genetically identical offspring from a single parent plant using tissue cultures techniques
when is micropropagation used
When the desirable plant…
- doesn’t readily produce seeds
- doesn’t respond well to natural cloning
- is very rare
- has been genetically modified or selectively bred with difficulty
- is required to be ‘pathogen-free’ by growers
what is the process of micropropagation using tissue culture
1) Take a small sample of tissue from the plant you want to clone. (The meristem tissue from shoot tips and axial buds is often dissected out in sterile conditions to avoid contamination by fungi and bacteria. Usually virus free).
2) Sterilise the sample by immersing in sterilising agents. The latter isn’t rinsed off. The material removed is called the explant.
3) The explant is placed in a sterile culture medium containing a balance of plant hormones (auxins and cytokinins) which stimulate mitosis. The cells multiply, forming a mass of identical cells called a callus.
4) The callus is divided up and individual cells or clumps from the callus are transferred to a new culture medium containing a different mixture of hormones and nutrients which stimulates the development of plantlets.
5) The plantlets are potted into compost where they grow into small plants.
6) The young plants are planted out to grow and produce a crop.
What are the reasons for micropropagation?
- Allows for the rapid production of large numbers of plants which will yield good crops.
- Culturing meristem tissue produces disease-free plants.
- Makes it possible to produce viable numbers of plants after genetic modification of plant cells.
- Provides a way of producing very large numbers of new plants which are seedless and meets consumer tastes.
- Provides a way of growing plants which are naturally relatively infertile or difficult to grow from seed.
- Provides a way of reliably increasing the numbers of rare or endangered plants.
what are the reasons against micropropagation?
- produces a monoculture (many plants that are genetically identical) so all are susceptible to the same diseases or changes in growing conditions.
- relatively expensive process and requires skilled workers.
- the explants and plantlets are vulnerable to infection
- if the source material is infected with a virus, all clones will also be infected.
- in some cases, large numbers of new plants are lost during the process
what is the step-by-step process of artificial embryo twinning (using cows as an example)
1) An egg cell is extracted from a female cow and fertilised in a Petri dish.
2) The fertilised egg is left to divide at least one, forming an embryo (outside a living organism).
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 re then implanted into female cows, which act as surrogate mothers.
5) The embryos continue to develop inside the surrogate cows and eventually offspring are born, all genetically identical to each other.
Give the step-by-step process of somatic cell nuclear transfer (SCNT) (using sheep as an example)
1) A somatic cell is taken from sheep A. The nucleus is extracted and kept.
2) An egg cell (oocyte) is taken from sheep B. Its nucleus is removed to form an enucleated oocyte.
3) The nucleus from sheep A is inserted into the enucleated oocyte so the oocyte from sheep B now contains the genetic information from sheep A.
4) The nucleus and the enucleated oocyte are fused together and stimulated to divide (electrofusion - applying an electric current). This produces an embryo.
5) The embryo is then implanted into a surrogate mother and eventually a lamb is born that’s a clone of sheep A.
what is therapeutic cloning
cloning our own body cells in order to produce new organs
this is beneficial because the body won’t reject the organs (in transplants for example)
Give some different ways vegetative propagation is used in horticulture
2) Grafting - joining the shoot of one plant to the stem and root of another
3) Layering - bending a stem of a growing plant downwards so it enters the soil an grows a new plant
4) Split up bulbs
5) Remove young plants from runners
6) Cut up rhizomes (horizontal roots grown underground which produce own shoots)
What are the arguments for animal cloning
- Desirable genetic characteristics are always passed onto clones (eg. high yield)
- Infertile animals can be reproduced
- Animals can be cloned at any time - don’t have to wait till breeding season
- Increasing the population of endangered species helps to preserve biodiversity
- Cloning can help us develop new treatments for disease, which could mean less suffering for some people
What are the arguments against animal cloning
- Animal cloning is very difficult, time-consuming and expensive.
- There’s no genetic variability in cloned populations so undesirable genetic characteristics are always passed on to clones. This means all clones are susceptible to the same diseases so they could all wipe out.
- Evidence suggests clones don’t live as long as natural offspring. Some think this is unethical.
- Using cloned human embryos as a source of stem cells s controversial. The embryos are usually destroyed after the embryonic stem cells have been harvested - could be considered as destroying a human life.
industrial use of living organisms to produce food, drugs and other products
Why are microorganisms used in biotechnology
- ideal growth conditions easily created
- grow rapidly due to short life cycle so products made quickly
- grown on a range of inexpensive materials
- grown anytime of year
- no welfare issues to consider
- large range of microorganisms capable of different chemical synthesis or degradation
- can artificially manipulate them eg. genetic engineering
How is lactase used in biotechnology
Breaks down lactose
Made from Asperigillus fungi
Used to produce lactose-free products
What are intracellular enzymes
enzymes are contained within cells of a microorganism
what are isolated enzymes
enzymes that aren’t contained in cells
- extracellular enzymes which are secreted naturally by the microorganism
- some have to extracted from cells artificially
what are the indirect ways microorganisms are used in biotechnology
the actions of the microorganisms are what’s important
eg. bread - yeast makes it rise, yoghurt, cheese, beer
needs ideal conditions
needs to be sterile
the microorganisms used have been genetically engineered
what are the direct ways microorganisms are used in biotechnology
Using microorganisms to make proteins we can eat
eg. Quorn - made of fungus Fusarium venetatum
what microorganism is used in baking and how does it work
The carbon dioxide produced by fermentation of sugars in the dough makes sure it doesn’t stay flat
what microorganism is used in brewing and how does it work
Added to barley (type of grain). The yeast respires anaerobically using the glucose from the grain and produces ethanol and carbon dioxide. (Fermentation)
what microorganism is used in making cheese and how does it work
Substance called rennet which contains the enzyme chymosin. This clots milk. It’s extracted from yeast cells that have been genetically modified.
Also, lactic acid bacteria (Lactobacillus or Streptococcus) which converts lactose in milk into lactic acid which contributes to solidifying.
what microorganism is used in making yoghurt and how does it work
Lactic acid bacteria
Clots milk and causes it to thicken.
Makes it sour - flavours are added afterwards.
What are the advantages of using microorganisms in food production?
- Microorganisms used to make single-cell protein can be grown using many different organic substrates, including waste materials.
- They can be grown quickly, easily and cheaply. Only require simple growth requirements and can be grown on waste products and less land is required in comparison to growing crops or rearing livestock.
- Can be cultured anywhere if you have the right equipment so can be used in LEDCs
- Single-cell protein is also often considered a healthier alternative to animal protein
What are the disadvantages of using microorganisms in food production?
- Other microorganisms can grow in the conditions so it takes a lot of effort into making sure food doesn’t get contaminated with unwanted bacteria
- 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/flavour as real meat
- If single-cell protein is consumed in high quantities, health problems could be caused due to high levels of uric acid released when the large amounts of amino acids are broken down.
what are the aims of fermentation vessels
obtain lots of microorganisms or to collect lots of useful product the microorganism makes
what is batch fermentation
Microorganisms are grown in individual batches, 1 culture ends, its removed and then a different batch is grown in the vessel
This is known as closed culture
what is continuous fermentation
Microorganisms are continually grown in a fermentation vessel without stopping
Nutrients are added and waste products are removed at a constant rate
Conditions inside are kept at the optimum for growth – this maximises yield
This is known as open culture
what 5 things must be controlled in fermentation vessels
pH temperature oxygen supply nutrient concentration contamination
why must pH be controlled in fermentation vessels?
if waste products of microorganisms e.g., carbon dioxide build up then pH of mixture will decrease. Change in pH can affect enzyme action and stop growth, buffers are added to mixture and stirred in or alkaline solution added to maintain optimum pH.
why must temperature be controlled in fermentation vessels?
if temperature too low microorganisms will not grow quickly enough, too high and enzymes will start to denature and microorganisms are inhibited or destroyed.
A water jacket surrounds the fermentation vessel to maintain the temp.
why must oxygen supply be controlled in fermentation vessels?
if microorganisms use up oxygen they will start to die off so need a mechanism to keep nutrient medium oxygenated, oxygen is bubbled through broth when probes or sample tests indicate that levels are dropping to be mixed in using stirrers/paddles as will not spread through fast enough by diffusion alone.
why must nutrient concentration be controlled in fermentation vessels?
if microorganisms use up food supply they will start to die off so need a mechanism to keep food supplied, culture medium can be added in controlled amounts to broth when probes or sample tests indicate that levels are decreasing to be mixed in using stirrers/paddles as will not spread through fast enough by diffusion alone.
why must contamination be controlled in fermentation vessels?
Vessels are sterilised between uses with superheated steam to kill any unwanted organisms and make sure the next culture isn’t contaminated.
This increases the product yield because the microorganisms aren’t competing with other organisms.
Fermentation vessels may run batch or continuous processes. What is the difference? (6)
Continuous processes run continuously once fermentation is started (1);
sterile nutrient medium added continuously once culture is growing exponentially (1);
culture broth continually removed so product can be processed and culture volume remains the same (1).
Batch process everything added at beginning in fixed volume of medium (1);
nutrients used up and microorganisms, products, and waste products build up (1);
may be stationary phase when secondary metabolites formed, process stopped, products extracted, reactor cleaned, and new process begun (1).
define closed culture
The growth of microorganisms in an environment where the conditions are fixed. No new nutrients are added and waste products are not removed.
In a closed culture, a population of microorganisms follows a standard growth curve. What are the 4 phases and describe what’s happening.
1) The lag phase - where there is no reproduction but the cells are taking up water and are carrying out protein synthesis and producing enzymes.
2) The exponential phase or log phase - where the population increases rapidly.
3) The stationary phase - where bacterial cells are dying at the same rate as they are produced. Nutrients decrease, waste builds up.
4) The death or decline phase - where more cells are dying than are being produced. Nutrients are exhausted, toxic levels of waste.
What would the growth curve look like for continuous fermentation? How does it differ to the standard growth curve?
Horizontal line (lag phase) then straight line upwards (exponential/log phase).
Missing the stationary phase and death phase because the waste products are removed and oxygen and nutrients are continuously supplied.
What equation could you use to work out how many cells will be present in a population after a certain number of divisions?
No. of cells in population = initial no. of cells x 2^n
n is the number of divisions
For a species of bacteria, the cells divide approximately every 30 minutes during the exponential growth phase. There are 300 bacterial cells present at the start of the phase. Estimate how many cells are present after 7 hours.
7 hours = 420 minutes
Divide every 30 minutes so 420/30 = 14 divisions
No. of cells in population = initial no. of cells x 2^n
= 300 X 2^14
= 4.9 X10^6 cells
why is it easier to interpret data values from a logarithmic graph when looking at growth rate of microorganisms
because on a normal linear graph, the numbers are very clumped together at the start as the y axis has to cover a wide range of values
If you had a log graph showing the growth rate of a microorganism, how could you read how many microorganisms are present at a certain time?
Read the time from x axis and go up and across to the y axis
the number you read will be the log value so you have to do 10^x to calculate the actual number of microorganisms
How is penicillin produced
Mould called Penicillin chrysogenum.
Needs relatively high oxygen levels and a rich nutrient medium.
Semi-continuous batch process is used. Fungus grows in 1st stage and penicillin grows in 2nd stage.
Uses small fermenters to maintain high levels of oxygenation.
Mixture is continuously stirred to keep it oxygenated.
Rich nutrient medium.
Contains a buffer to maintain pH.
Bioreactors maintain temperature.
How is insulin produced as part of biotechnology
Insulin is made by genetically modified bacteria which have had the gene for human insulin production inserted into their DNA.
These bacteria are grown in an industrial fermenter on a massive scale and the insulin produced is collected and purified.
What is bioremediation
Using microorganisms to remove pollutants, like oil and pesticides, from contaminated sites.
Can use naturally occurring microorganisms which could provide nutrients to break down/neutralise contaminants.
Or can use GM organisms which break down contaminants which they woudlnt naturally encounter.
Give examples of all the aseptic techniques that should be carried out when culturing microorganisms
- Regularly disinfect work surfaces to minimise contamination.
- Work near a Bunsen flame so the hot air removes the microorganisms in the air.
- Sterilise the instrument used to transfer cultures before and after each use. Eg. put the inoculation loop through a Bunsen flame.
- If you’re using broth, briefly pass the neck of the broth container through a flame just after it’s opened and just before it’s closed.
- Minimise the time that the agar plate is open and put the lid on as soon as possible.
- Sterilise all glassware before and after use.
- Wear a lab coat and gloves. Tie long hair back.
Outline an experiment you can do to culture microorganisms.
1) Bacteria should be in a broth. Using a sterile pipette, add the same volume of your sample to each of the 6 agar plates. Discard pipette after use.
2) Spread the broth across the entire surface of the agar using a sterile plastic spreader.
3) Put the lids on the agar plates and tape them shut.
4) Place 3 plates in a fridge at 4 degrees and put 3 in an incubator at 25 degrees. Should be incubated upside down to stop condensation forming and dropping onto the agar.
5) Put another lidded agar plate in each of the 2 different temperatures which are uncultured. These are negative controls.
6) Leave all the plates for the same amount of time (24hours)
7) Observe the results - there will be colonies of bacteria
8) Count the number of colonies that have formed on each plate and record your results.
9) Work out the mean number of colonies formed at each temp.
How could you alter the experiment for culturing microorganisms to investigate the affect of pH
Add buffers at different pH levels to the broth
how do you make a serial dilution
1) In your 1st test tube put 2ml of pure culture (no broth)
2) Squeeze with pipette to mix
3) In the remaining 4 test tubes place 9ml of broth
4) From the original inoculum (pure culture), use a clean tip and take 1ml and add to 2nd test tube
5) Squeeze with pipette to mix, take a new tip and take 1ml and add to next test tube
6) Repeat for all 4 dilutions
give the procedure of how you sterilise the glass spreader used for spreading the culture on the agar plate
Dip the spreader in the ethanol
Tap twice to remove excess ethanol
Pull the glass spreader pointing downwards slowly through the flame
Do not put this down anywhere
Let the spreader cool down before putting in culture
Ensure you flame the culture bottle before and after use
what are the dilution factors of 4 test tubes if the first one has 9ml of broth and 1ml of pure culture and then 1ml of that solution is put in the next 9ml broth test tube and so on.
10^1 then 10^2, 10^3 and 10^4
because test tube one has the ratio 1:10 of culture:broth
test tube 2 is 1:100
test tube 3 is 1:1000
test tube 4 is 1:10000
how do you calculate the number of colonies in a sample
Count the number of colonies on the plate you have chosen from each set and record this number and the dilution factor for that plate.
(number of colonies counted x dilution factor) / vol on culture plate
volume is in ml
how could you use a colorimeter to find out the density of bacteria in a culture
why isn’t this as good as serial dilutions
Turbidity of the culture can be used, once a calibration curve has been produced from a known set of cultures. The % transmission of light through the culture can be measured with a colorimeter and the density of the unknown culture inferred from the calibration curve. This method takes no account of viability of cells so will give an overestimate, especially in old, high density cultures.
When observing your agar plates, how can you be confident that all the colonies you see are the same?
The quickest check to be made is simply colour and morphology of colonies. All colonies should look the same. Any different colonies are almost certainly the result of contamination.
Microscopic observation of samples from any suspect colonies, using identification aids such as Gram-staining, could confirm this.
what are the two types
the products of metabolism
primary and secondary
what are primary metabolites
Substances made by an organism as part of normal growth
Amino acids, proteins, enzymes, nucleic acids, ethanol and lactate.
These are made during the growth / log phase.
what are secondary metabolites
Substances made by an organism that are not part of normal growth.
Antibiotics, such as penicillin
These are produced after the growth phase and are made during the stationary phase.
All microbes produce ______ metabolites, but only a select few produce ______ metabolites.
All microbes produce PRIMARY metabolites, but only a select few produce SECONDARY metabolites.
Compare batch and continuous cultures
Batch are closed cultures whereas continuous are open cultures.
Phases involved in batch are lag, log, stationary and death phase. But, phases in continuous are just log and lag.
Primary and secondary metabolites are produced in batch but only primary metabolites are produced in continuous.
why do you get primary and secondary metabolites in batch fermentation
During the growth phase, there are plenty of nutrients and therefore all metabolic processes are dedicated to growth and so primary metabolites are made that aid the growth of the organism, such as proteins.
In the stationary phase, when nutrients are limiting, microbes switch to produce secondary metabolites, such as antibiotics. These will help to kill other microbes which could be in competition with the it.
simply, what is immobilisation of enzymes
any technique where enzyme molecules are held and separated from the reaction mixture
Substrate molecules can bind to the enzyme molecules and the products formed go back into the reaction mixture leaving the enzyme molecules in place.
what are the 4 ways you can immobilise enzymes
1) Encapsulated/entrapped in jelly-like alginate beads, which act as a semi-permeable membrane.
2) Trapped in a silica gel matrix.
3) Covalently bonded to insoluble material like cellulose or collagen fibres.
4) Adsorption - enzyme molecules adsorbed to inorganic carriers e.g. cellulose, silica
how do columns of immobilised enzymes work
The substrate solution is run through a column of immobilised enzymes
The active sites of the enzymes are still able to catalyse the reaction
The solution flowing out of the column will only contain the desired product
what are the advantages of using immobilised enzymes
- columns of immoblised enzymes can be washed and reused - this reduces the cost of running a reaction on an industrial scale because 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 enyzmes - they’re less likely to denature (become inactive) in high temperatures or pH extremes
what are the disadvantages of using immobilised enzymes
- extra equipment is required which can be expensive to buy
- immobilised enzymes are more expensive to by than free enzymes, 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
how are immobilised enzymes used to convert lactose to glucose and galactose
Fresh milk can be passed over immobilised lactase to produce lactose-free milk.
Lactase breaks down lactose into glucose and galactose via a hydrolysis reaction.
how are immobilised enzymes used to produce semi-synthetic penicillins
some bacteria are resistant to penicillin so semi-synthetic penicillin has been produced which has an effect
immobilised penicillin acylase enzyme is used
how are immobilised enzymes used to convert dextrins to glucose
glucose can be derived from starchy food with the help of immobilised enzymes
starch breaks down into dextrins which are then broken down into glucose by the immobilised enzyme glucoamylase
how are immobilised enzymes used to convert glucose to fructose
fructose can be used instead of glucose - you need less for the same level of sweetness
immobilised glucose isomerase is used
how are immobilised enzymes used to produce pure samples of L-amino acids
amino acids have 2 chemical forms - L or D
most amino acids utilised by the body need to be in the L form
scientists are able to chemically synthesise amino acids, but end up with a mix of L and D forms
the enzyme aminoacylase separates them
L-amino acids can then be used for lots of things like dietary supplements or animal/human food
why are immobilised enzymes used to convert acrylonitrile to acrylamide
acrylamide is a chemical that is typically used in industry to produce synthetic polymers
immobilised nitrilase is used to covert acrylonitrile (a man-made chemical) to acrylamide