1
Q
What are clones and how are they produced?
A
clones are genetically identical copies.
they are produced by asexual reproduction in which the nucleus is divided by mitosis.
2
Q
how does mitosis create a clone?
A
mitosis creates two identical copies of DNA before cell division. it divides to form two genetically identical cells.
3
Q
name some advantages of natural cloning.
A
- if the conditions of growth are good for the parent, then they will be good for the offspring.
- cloning is relatively rapid, the population can increase quickly.
- reproduction can be carried out even if there is only one parent or sexual reproduction is not possible.
4
Q
name some disadvantages of natural cloning.
A
- the offspring may become overcrowded.
- there will be no genetic diversity (except any caused by mutations in DNA replication).
- the population shows little variation.
- selection is not possible.
- the whole population is susceptible to changes in the environment.
5
Q
what is vegetative propagation?
A
plants are able to clone naturally and vegetative propagation is a process within this cloning.
it is the process of reproduction through the vegetative parts of the plant, rather than through specialised reproductive structures.
6
Q
what are runners/stolons?
A
these are horizontal stems that can form roots at certain points on the surface of the ground.
7
Q
what are rhizomes?
A
these are horizontal stems that can form roots at certain points underground.
8
Q
what are suckers?
A
these are new stems that grow from the roots of a plant. the original horizontal plant may die, leaving the new stem as a separate individual.
9
Q
what are bulbs?
A
bulbs are a mechanism that many plants use over winter.
bulbs consist of an underground stem which can grow many fleshy leaf bases.
10
Q
what are corms?
A
corms are solid rather than fleshy, like bulbs.
they are an underground stem with scaly leaves and buds.
corms remain in the ground over winter but produce buds in the spring.
11
Q
how can leaves produce clones?
A
some leaves reproduce by producing clones on their leaf margins.
these clones drop off the leaf and take root.
12
Q
what are tubers?
A
tubers are an example of an underground stem that will grow into many other plants. for example, if you plant a potato, it will grow into one or more plants.
13
Q
name some examples of natural clones in animals
A
mammals clone when identical twins are formed.
this occurs when a fertilised egg divides as normal but the two daughter cells then split to become 2 separate cells which then grow and divide into new individuals.
14
Q
what is the easiest way to clone a plant?
A
the easiest way to make a clone of a plant is to take a cutting.
15
Q
how do you clone a plant by a cutting?
A
to make a cutting:
- a stem is cut between two leaf joints
- the cut end is placed into moist soil
- OPTIONAL - treat the cut end with rooting powder or plant hormones
- new roots grow from the cut stem
16
Q
where can cuttings be taken from?
A
- between two leaves on the stem
- roots
- scions
- leaves
17
Q
what is one disadvantage of cloning plants by cuttings on a large scale?
A
large scale cloning by cuttings can be time and space consuming.
18
Q
what is tissue culture?
A
using cells or tissue to grow cells, tissues or organs.
tissue culture is widely used commercially in micropropagation.
19
Q
what is micropropagation?
A
micropropagation involves taking an explant (a small piece of plant tissue) and using growth substances to encourage it to grow into a whole plant.
20
Q
describe the process of micropropagation.
A
- suitable plant material is selected - EXPLANTS
- the explants are sterilised using dilute bleach or alcohol. this kills any bacteria or fungi.
- the explants are placed into a sterile growth medium containing suitable nutrients and plant growth substances. a CALLUS is formed.
- once a callus has formed, it is divided into small clumps.
- the small clumps of cells are stimulated to grow, divide and differentiate into different plant tissues by being placed in different mediums with different ratios of growth substances.
- once tiny plantlets have been formed, they are transferred to a greenhouse and grown in compost or soil.
21
Q
what do the plant growth substances do to the explant?
A
the growth substances stimulate the cells of each explant to divide by mitosis to form a callus (a mass of totipotent, undifferentiated cells.
22
Q
what are the advantages of artificial cloning of plants?
A
- it is relatively rapid compared to growing plants from a seed.
- cloning can be carried out where sexual reproduction is not possible.
- plants that are difficult to grow from a seed can be reproduced.
- the plants selected will all be genetically identical to the parent plant and therefore display the same desirable characteristics e.g. high yield.
- they are all uniform in appearance.
- using plant meristem as an explant ensures that the new plants are free from viruses.
23
Q
what are the disadvantages of artificial cloning of plants?
A
- tissue culture is labour intensive.
- it is expensive to set up the facilities to perform tissue culture successfully.
- all cloned offspring are genetically identical and are susceptible to the same pests and diseases.
- there is no genetic variation.
24
Q
what are the only truly totipotent cells in animals and why are they useful in cloning?
A
the only truly totipotent cells in cloning are early embryo cells.
they are useful in cloning because successful cloning begins with cells that can divide and differentiate into all types of adult cells, which these totipotent cells can.
25
how can cloning in animals be useful?
cloning can be useful for:
- elite farm animals that are produced by selective breeding.
- genetically modified animals that have been developed with unusual characteristics e.g. cows that produce less methane.
26
what are the two main techniques used to achieve reproductive cloning in animals?
- embryo twinning
| - somatic cell nuclear transfer
27
describe the process of embryo splitting.
1. a zygote (fertilised egg) is created by IVF.
2. the zygote is allowed to divide by mitosis to form a small ball of cells.
3. the cells are separated and are allowed to continue to divide.
4. each small mass of cells is placed into the uterus of a surrogate mother.
28
can embryo splitting clone an adult?
no. only somatic cell nuclear transfer can clone an adult.
29
describe the process of somatic cell nuclear transfer.
1. an egg cell is obtained and its nucleus is removed - enucleation.
2. a normal body cell from the adult to be cloned is isolated and the nucleus is removed.
3. the nucleus is fused with the egg cell by applying an electric shock.
4. the shock also triggers the effects to begin developing as if it has just been fertilised.
5. the cell undergoes mitosis. the embryo produced is placed into a surrogate.
30
what is non-reproductive cloning?
non-reproductive cloning is when cells or tissues are cloned for purposes other than reproduction.
31
what is therapeutic cloning?
this is a type of non-reproductive cloning.
new tissues and organs are grown as replacement parts for people who are not well. e.g. skin can be grown to graft over burnt areas.
32
why are tissues grown through non-reproductive cloning useful?
they are useful as the cells will be identical to the patients own and therefore avoid rejection.
33
why is cloning useful in scientific research?
cloned genetically identical embryos can be used in scientific research into the action of genes.
tissues or organs can also be grown to test the effects of drugs.
34
name some arguments FOR artificial animal cloning.
- can produce a whole herd of animals with desirable characteristics.
- produces genetically identical copies of a high value individual.
- testing medicinal drugs upon cloned cells and tissues avoids using people or animals.
- it can produce cells and tissues that are genetically identical to the donor, for use in repairing damage caused by disease or accidents.
- individuals from an endangered species can be cloned to increase numbers.
35
name some arguments AGAINST artificial animal cloning.
- lack of genetic variation may expose the animals to certain diseases or pests.
- animals may be produced with little regard for their welfare.
- cloned animals may be less healthy and have shorter life spans.
- there are ethical issues regarding how long the embryo survives for and whether it is right to create life to simply destroy it.
- producing members of an endangered species does not help to increase genetic diversity.
36
how long has biotechnology been used for?
the oldest documented evidence of brewing of beer was 7000 years ago.
37
give some examples of biotechnology in food.
- Ethanol in beer and wine --> produced by yeast
- Carbon dioxide in bread --> produced by yeast
- Lactic acid used to make yoghurt and cheese --> lactobacillus
- Mycoprotein (Quorn) --> made from a fungus
38
give some examples of biotechnology in pharmaceutical drugs
- Penicillin --> produced by the penicillium fungus
| - Insulin --> produced by GM bacteria
39
give some examples of biotechnology in enzymes.
- Protease and lipase in washing powder --> bacteria
| - Lactase to make lactose-free milk.
40
give some examples of where biotechnology can be used to produce other products.
- Biogas --> anaerobic bacteria
| - Bioremediation --> a variety of bacteria are used.
41
what are some advantages of using microorganisms in biotechnology?
- they are cheap and easy to grow
- production takes place at lower temperatures which saves fuel and reduces costs
- the production takes place at normal atmospheric pressure. this is safer than using chemical reactions with high pressures.
- the production process is not dependent upon climate so it can take place anywhere
- microorganisms can be fed by-products from other industries e.g. starch or waste water
- microorganisms have a short life cycle and reproduce quickly, therefore, a large population can be grown quickly.
- microorganisms can be genetically modified relatively easily. this means that special production processes can be achieved.
- there are fewer ethical considerations to worry about.
- the products are easy to harvest and this is often purer than in chemical processes, resulting in lower downstream processing costs.
42
list some forms of biotechnology.
- gene technology
- genetic modification and gene therapy
- selective breeding
- cloning
- use of enzymes in industry
43
how are microorganisms used to produce yoghurt?
yoghurt is milk that has undergone fermentation by bacteria.
the bacteria convert lactose to lactic acid. the acidity denatures the milk protein and causes it to coagulate.
fermentation also produces flavours that are characteristic to yoghurt.
44
how are microorganisms used to produce cheese?
milk is treated with a culture of bacteria and once acidified, the milk is mixed with rennet. rennet contains rennin which coagulates the milk protein.
the resulting solid is called curd. it is separated from the liquid component (whey) and the bacteria continue to grow, producing more lactic acid. the curd is pressed into moulds.
the flavour of cheese is determined by the maturing and ripening process.
fungi can be used additionally in cheese to produce mouldy "blue cheese".
45
how are microorganisms used to produce bread?
bread is a mixture of flour, water, salt and yeast.
breadmaking involves 3 steps:
1. mixing
2. proving/fermenting = the dough if left so that the yeast can respire and produce carbon dioxide bubbles which cause the dough to rise.
3. cooking = any alcohol evaporates during the cooking process.
46
how are microorganisms used to produce alcoholic beverages?
alcoholic beverages are the product of the anaerobic respiration of yeast.
wine is made using grapes which naturally have yeasts in their skins. grapes contain the sugars, glucose and fructose which when crushed, allows the yeast to respire the sugars to produce alcohol.
beer is made using germinating barley grains in a process called malting.
47
how can microorganisms be used to produce single-cell protein (SCP)?
fungi can be used to produce food such as mycoprotein/single-cell protein/Quorn.
it is marketed as a meat substitute for vegetarians or non-vegetarians. it is healthy as it contains no animal fat or cholesterol.
SCP can grow on almost any organic substrate, including waste materials such as paper or whey.
48
name some advantages of using microorganisms to produce SCP
- production of protein can be faster than that of animal or plant protein.
- the biomass produced has a high protein content.
- production can be increased/decreased to meet demand.
- no animal welfare issues.
- provide a good source of protein with no animal fat or cholesterol.
- production is independent of weather or seasonal variations.
- not much land is required.
49
name some disadvantages of using microorganisms to produce SCP
- some people do not want to eat fungi
- the protein has to be purified to ensure that it is uncontaminated.
- care must be taken to ensure that the culture is not infected with the wrong organisms.
- palatability - the protein does not have the taste or texture of traditional protein sources.
50
what conditions are present within a fermenter?
the conditions include:
- temperature = too hot and the enzymes denature, too cold and productivity will be too low.
- nutrients available = sources of nutrients are needed so that the microorganisms can grow.
- oxygen availability = most microorganisms respire anaerobically.
- pH = enzyme activity, growth and synthesis are affected by extremes of pH.
- concentrations of product = if the product is allowed to build up, it may affect the synthesis process.
51
what must happen to a fermenter before it is used?
before use, a fermenter must be sterilised using superheated steam.
52
what are primary metabolites?
primary metabolites = products synthesised during the normal metabolism of a microorganism
primary metabolites are continuously released from cells and can be extracted continuously from the fermenting broth.
53
what is a continuous culture?
a continuous culture consists microorganisms growing at a specific growth rate and producing primary metabolites.
occasionally the broth is topped up with nutrients and some of the culture is removed regularly to extract the product.
54
what are secondary metabolites?
secondary metabolites = products which are only produced when cells are under stress.
they are mostly produced during the stationary phase of cell growth
55
what is a batch culture?
a batch culture is a culture of microorganisms that produce secondary metabolites.
it is set up with a limited availability of nutrients and is allowed to ferment for a specific time.
after the specific time, the fermenter is emptied and the product can be extracted from the culture.
56
what is asepsis?
asepsis = ensuring that sterile conditions are maintained.
57
why should a fermenter be aseptic?
a fermenter should be aseptic because the nutrient medium contained within it would support the growth of unwanted microorganisms which would reduce production.
58
why would the growth of unwanted organisms reduce the production of a fermenter?
unwanted organisms would:
- compete with cultured microorganisms for nutrients and space.
- replace the yield of useful products.
- spoil the product
they may also:
- produce toxic waste products
- destroy the cultured microorganisms and their products
59
what happens if a fermenter is contaminated in food or medicine production?
in processes where foods or medicinal chemicals are produced, if contamination occurs, all products must be discarded.
60
how can penicillin be produced in a fermenter?
penicillin can be mass produced through fermentation of the fungus "Penicillium Chrysogenum"
penicillin is manufactured by batch culture because it is a secondary metabolite - it is only produced once the population has reached a certain size.
61
describe the process of producing penicillin.
1. the fermenter is run for 6-8 days.
2. the culture is filtered to remove the cells
3. the antibiotic is precipitated by the addition of potassium compounds.
4. the antibiotic is mixed with inert substances and prepared as a tablet, syrup of form suitable for injection.
62
how can insulin be produced by fermentation?
insulin can be produced synthetically by genetically modified bacteria.
the gene for human insulin in combined with a plasmid and inserted into the e-coli bacterium.
the resulting genetically modified bacteria produces vast quantities of insulin.
63
is production of insulin batch of continuous culture?
it is CONTINUOUS.
this is because insulin is produced as a primary metabolite of the e-coli.
64
what is bioremediation?
bioremediation is the use of microorganisms to clean the soil and underground water from polluted sites.
the organisms convert the toxic pollutants into less harmful substances.
65
what does bioremediation require?
bioremediation requires the right conditions:
- available water.
- a suitable temperature
- a suitable pH
66
what happens if the conditions for bioremediation are not suitable?
the conditions may be modified by the addition of suitable substances.
where conditions cannot be made suitable in situ, the soil may be dug up and moved to be treated ex situ
67
what are some advantages of bioremediation?
- uses natural systems
- less labour/equipment is required.
- treatment in situ
- few waste products
- less risk of exposure to clean up personnel.
68
what is a problem with bioremediation?
it is only suitable for certain products. some cannot be cleaned up.
69
what are the two main types of growth medium?
1. a soup-like liquid called a broth.
| 2. agar which is poured into Petri dishes.
70
what are aseptic techniques?
techniques that have been developed to reduce the likelihood of contaminating the growth medium with unwanted micro-organisms.
71
what is the standard aseptic procedure?
1. wash your hands
2. disinfect the working area.
3. set up a Bunsen burner.
4. if a bottle is opened, the neck of the bottle should be flamed to prevent bacteria from entering it.
5. do not lift off the Petri dish lid entirely.
6. any glassware/metal should be passed through the flame before and after contact with microorganisms.
72
what are the three main stems involved in growing microorganisms on agar plates?
1. sterilisation
2. inoculation
3. incubation
73
how is equipment sterilised?
the equipment is sterilised by heating it in an autoclave at 121 degrees for 15 minutes. this kills all living organisms
74
what is inoculation?
inoculation is the introduction of microorganisms into the sterile medium.
75
how can inoculation be achieved? (4 methods)
- streaking = a wire inoculating loop is used to transfer a drop of liquid medium on to the surface of the agar and spread it in a loop.
- seeding = a sterile pipette can be used to transfer a small drop of liquid medium on to the surface of the agar.
- spreading = a sterile glass spreader is used to spread the inoculated drop over the surface of the agar.
- a small cotton swab can be moistened with distilled water and used to collect microorganisms from a surface and then carefully wipe them over the surface of the agar.
76
how is a Petri dish incubated?
a petri dish is labelled and the top is taped down.
the dish is then placed in a suitable warm environment such as an incubator. it should be placed upside down as thus prevents drops of condensation from falling on to the agar.
77
why should the lead of the Petri dish not be taped down so that it is sealed completely?
if it is sealed completely, this can lead to the selection of anaerobic bacteria.
78
how long should a culture be incubated for?
24-36 hours.
the Petri dish lid SHOULD NOT be opened.
79
why should you wash your hands after handling a Petri dish?
any moisture coming out of the dish could be a source of infection.
80
what happens to a liquid medium when bacteria have grown?
when bacteria have grown, the broth (which was initially clear) will turn cloudy.
81
how can a liquid broth be used to measure the growth rate of a micro-organism population?
a sterile broth is innoculated and the population size is measured at regular intervals.
82
why must serial dilutions take place when observing microorganism populations in a liquid broth?
if the broth is used to inoculate an afar plate and there are too many individual microorganisms, there may be too many colonies which can merge together.
this makes counting impossible.
83
how does serial dilution work?
at each step, the broth is diluted.
a drop of each dilution can be used to inoculate an agar plate. one of these dilutions will produce a culture plate in which the number of colonies can be counted.
84
what is a closed culture?
a closed culture is a culture in which the conditions are set from the start and there is no exchange with the internal environment.
85
does batch production use closed culture?
similar conditions to closed culture are used in batch production. however, certain substances may be added to keep the population growing until all of the nutrients are used up.
86
what are the four stages of the growth curve in order?
1. the lag phase
2. the log/exponential phase
3. the stationary phase
4. the death/decline phase
87
what is the lag phase? describe what happens within it
```
the population does not grow quickly.
the population is small and the organisms are adjusting to their new environment.
this adjustment may involve:
- taking up water
- cell growth
- activating certain genes
- synthesising specific proteins
```
88
describe what happens in the log/exponential phase
in the log phase, the organisms have adjusted to their environment. they have:
- the enzymes needed to survive.
- the sufficient nutrients and space.
the population doubles in size with each generation.
89
describe what happens within the stationary phase?
eventually, the increasing numbers of organisms use up the nutrients and produce increasing amounts of waste products such as carbon dioxide.
the rate of population growth declines and the number of individuals dying increases. there is no population growth.
90
describe what happens in the death phase.
in the death phase, nutrients run out and the concentration of waste products may become lethal.
more individuals die than are produced and eventually the population begins to fall. eventually all of the organisms die.
91
what is the issue with using enzymes that have not been immobilised in biotechnology?
the enzymes are not used up in reactions and remain in suspension when the reaction has been completed.
in industrial processes, this could be expensive as the enzyme would have to be isolated from the product.
92
what makes immobilised enzymes different from normal enzymes?
immobilised enzymes are taken out of suspension and are held so what they do not mix freely with the substrate.
93
what are some advantages of using immobilised enzymes?
- extraction costs are low.
- the enzymes can be easily reused.
- a continuous process is made easier as there are no cells requiring nutrients or releasing waste products.
- the enzymes are surrounded by the immobilising matrix and are therefore less affected by higher temperatures or wider pH's.
94
name the 4 methods of immobilising an enzyme
1. adsorption
2. membrane separation
3. entrapment
4. covalent bonding
95
describe how enzymes are immobilised using adsorption.
enzyme molecules are bound to a supporting surface by a combination of hydrophobic interactions and ionic links.
the enzyme molecules are bound with their active site exposed and accessible to the substrate.
96
what is the issue with adsorption?
bonding forces are not always strong and become detached. this leaks enzymes into the reaction mixture.
97
describe how enzymes are immobilised using covalent bonding.
enzyme molecules are bonded to a supporting surface such as clay using strong covalent bonds.
the enzymes are bonded using cross-linking which may also link them in a chain.
98
what is an issue with covalent bonding?
production of covalent bonding can be expensive and can distort the enzymes active site, reducing its activity.
99
describe how enzymes are immobilised using entrapment
enzyme molecules are trapped in a matrix that doesn't allow free movement. the substrate molecules diffuse in and out of the matrix.
the enzyme molecules are unaffected by entrapment and remain fully active.
100
what is an issue with entrapment?
the method is only suitable for processes with small substrate and product molecules.
101
describe how enzymes are immobilised using membrane separation.
enzyme molecules are separated from the reaction mixture by a partially permeable membrane.
102
what is an issue with membrane separation?
the substrate and product molecules must be small enough to pass through the partially permeable membrane by diffusion.
this access to enzymes may limit the rate of reaction.
103
how is the immobilised enzyme glucose isomerase used in industry?
this enzyme converts glusose to fructose which is used to produce high fructose corn syrup (HFCS).
HFCS is used in "diet foods' as less sugar needs to be added for the equivalent sweeteners.
it may also be used as a sweetener of foods for diabetics.
104
how is the immobilised enzyme penicillin acylase used in industry?
these enzymes are used in the formation of semi-synthetic penicillin.
105
how is the immobilised enzyme lactase used in industry?
lactase converts lactose into glucose and galactose by hydrolysis. this produces lactose-free milk.
milk is an important source of calcium and by creating lactose free milk, it therefore enables people who are lactose intolerant to get a good source of calcium.
106
how is the immobilised enzyme aminoacylase used in industry?
this is used to produce pure samples of L-amino acids.
L-amino acids are used as the building blocks for synthesis of a number of pharmaceutical and agrochemical compounds.
107
how is the immobilised enzyme glucoamylase used in industry?
this converts dextrin's into glucose which are produced in the hydrolysis of starch.
it is used in a wide range of fermentation processes, including the formation of gasohol.
108
how is the immobilised enzyme nitrile hydratase used in industry?
nitrile hydratase is used to produce substances used in plastic thickeners.
OCR Biology A-Level
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