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A-level Biology > 6.22 - Cloning and biotechnology > Flashcards

6.22 - Cloning and biotechnology Flashcards

1
Q

asexual reproduction

A
  • a form of cloning
  • results by offspring produced by mitosis known as clones
  • usually genetically identical to parent and siblings
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2
Q

natural cloning/ vegetative propagation

A
  • occurs in many species of flowering plants
  • a structure forms which develops into a fully differentiated new plant genetically identical to the parent
  • may be propagated from the stem, leaf, bud or root of the plant depending on the species
  • eventually becomes independent from its parent
  • often involved perennial organs that enable plants to survive adverse conditions so plants survive from one germinating season to another
  • organs contain stored food from photosynthesis but are also a means of asexual reproduction
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3
Q

cloning from bulbs

A
  • leaf bases swell with stored food from photosynthesis
  • buds form internally which develop into new shoots and plants in the next growing season
  • daffodil, tulips, onions, garlics
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4
Q

cloning from runners

A
  • lateral stem grows away from parent plant
  • roots develop where runner touches ground
  • new plant develops, runner withers away so plant becomes independent
  • strawberry, spider plant
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5
Q

cloning from rhizomes

A
  • specialised horizontal stems
  • often swollen with stored photosynthesis products
  • buds develop and form new vertical shoots which become independent plants
  • marram grass, hops, ginger
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6
Q

cloning from stem tubers

A
  • tip of underground stem becomes swollen with stored food to form a tuber/storage organ
  • buds on the storage organ develop to produce new shoots e.g. eyes on potatoes
  • potatoes, carrots, beetroot
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7
Q

using natural clones in horticulture

A
  • splitting rhizomes and runners and removing young plants increase plant numbers cheaply that have the exact same genetic characteristics as their parents
    Taking cuttings
  • Short sections of stems are taken and planted either directly in the ground or in pots
  • Rooting hormone is often applied to the base of the cutting to encourage the growth of new roots.
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8
Q

how to take cuttings

A
  • Use a non flowering stem
  • make an oblique cut in the stem
  • use hormone rooting powder
  • Reduce leaves to two or four
  • Keep cutting well watered
  • Cover cutting with a plastic bag for a few days.
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9
Q

cloning sugar cane

A
  • An internationally important crop for sugar and bio fuels
  • usually propagated by cloning
  • Short lengths of cane, around 30cm long with three nodes are cut and buried in a clear field in shallow trenches and covered with a thin layer of soil
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10
Q

Advantages and disadvantages of using cuttings

A

+ genetically identical to parent
+ Likely to produce good crops
+ Shorter time from planting to crop
+ Reliable
+ Don’t have to buy seeds
+ Can use own plants
- May require specialist skills
- Lack of variation means susceptible to change
- May require resources such as rooting hormones

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11
Q

Advantages and disadvantages of using seeds

A

+ Variation therefore more resistant to change
+ can collect seeds and use them for the next planting
+ Easier to transport
- Greater variability in quality of crops
- takes time and right conditions to germinate and mature
- seeds may not germinate
- The next generation of seeds may not have the same quality.

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12
Q

Why use artificial cloning to produce plants?

A
  • There is a limit to how many natural clones you can make from one plant
  • Many plant cells are totipotent, so scientists have developed ways of using this property to produce huge numbers of clones from one desirable plant.
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13
Q

Micropropagation using tissue culture.

A

Making large numbers of clones from a single parent plant using tissue culture techniques
- Take small samples tissue from the plant you want to clone (meristem tissue from shoot tips and axial buds are often dissected out in sterile conditions to avoid pathogen contamination)
- Sample is sterilised, usually by immersing it in sterilising agents such as bleach, ethanol or sodium dichloroisocyanurate sterilising tablets
- Explant placed in sterile culture medium containing a balance of plant hormones (e.g. auxins, cytokines) which stimulate mitosis forming a mass of identical cells known as a callus
- callus is divided up and individual new cells/clumps are transferred to a new culture medium containing hormones and nutrients which stimulate the development of tiny new plantlets
- the plantlets are potted into compost where they grow into small plants
- The young plants are planted out to grow and produce a crop

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14
Q

when is micropropagation using tissue culture used

A

used when a desirable plant:
- does not 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.

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15
Q

sodium dichloroisocyanurate sterilising tablets

A

used to sterilise tissue cultures in micropropagation
- useful when in the field, so not in a sterile lab
- does not need to be washed off so more likely to remain sterile

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16
Q

Increasing the scale of micropropagation.

A

Takes place in bioreactors making artificial embryo plants to be packaged into artificial seeds.

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17
Q

Advantages of micropropagation.

A
  • Rapid production of large numbers of plants with known genetic makeup which yield good crops
  • culturing meristem tissue produces disease free crops
  • makes it possible to produce viable number of plants after genetic modification
  • a way of producing sterile plants such as bananas and grapes to meet consumer tastes
  • A way of producing naturally infertile or difficult to grow plants like orchids
  • a way of reliably increasing the number of rare or endangered plants.
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18
Q

Disadvantages of micropropagation.

A
  • Produces a genetically identical monoculture, so all are susceptible to the same diseases or changes in growing conditions
  • Relatively expensive process
  • requires skilled workers
  • explants and plantlets are vulnerable to infection by moulds and other diseases during the production process.
  • If the source material is infected with a virus, all of the clones will also be infected
  • In some cases, large numbers of new plants are lost during the process.
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19
Q

Artificially twinning an animal

A
  • An ova from a cow with desirable characteristics is fertilised using artificial insemination or IVF
  • early embryos are removed
  • Early embryo is split into smaller groups of totipotent cells
  • Smaller embryos are incubated in lab and grown and monitored
  • Embryos implanted into uterus of surrogate mothers
  • Embryos develop into foetuses and identical clones are born naturally.
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20
Q

Adult cell cloning/Somatic cell nuclear transfer.

A
  • Somatic cells from adult donor cultured and ovum harvested from a different donor
  • Nucleus is removed from egg cell (and sometimes somatic cell) - enucleation
  • Cells are fused using electrofusion and begin to divide due to current
  • The developing embryo is implanted into the uterus of a surrogate sheep
  • Surrogate births a clone of the donor (mitochondrial DNA is from the egg cell)
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21
Q

Cloning in invertebrates.

A
  • Some animals, such as starfish, can generate entire animals from fragments of the original if damaged
  • flat worms and sponges fragment and form new clones as part of their normal reproductive process
  • Hydra produced small buds on the side of their body, which developed into genetically identical clones
  • In some insects, females can produce offspring without mating, as a result of high mutation rates, offspring may not be true clones.
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22
Q

Formation of identical/monozygotic twins.

A
  • Main form of vertebrate cloning
  • Early embryo splits to form two separate embryos
  • Frequency of identical twins varies between species
  • Twins may look different due to nutrition and position in the uterus.
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23
Q

cloning in amphibians.

A
  • Some female amphibians and reptiles will produce offspring when no male is available.
  • Offspring are often male so are not clones but have all of the mothers genetic material.
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24
Q

Arguments for animal cloning

A
  • Artificial twinning allows high yielding farm animals to produce more offspring than normal.
  • Artificial twinning allows determination of success of passing undesirable traits.
  • Somatic cell nuclear transfer allows genetically modified embryos to be replicated.
  • Allows production of important proteins for human therapy from genetically modified organisms (pharming)
  • somatic cell nucleus transfer allows cloning of specific animals, e.g. race horses or pets
  • somatic cell nuclear transfer has to potential to reproduce rare, endangered or extinct organisms.
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25
Q

arguments against animal cloning

A
  • somatic cell nuclear transfer is inefficient and takes many eggs to produce a single cloned offspring
  • many cloned animal embryos fail to develop and miscarry or produce malformed offspring.
  • Many animals produced by cloning have shortened lifespans
  • Somatic cell nuclear transfer has been relatively unsuccessful in increasing the populations of rare organisms or allowing extinct species to be brought back to life.
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26
Q

biotechnology

A

applying biological organisms/enzymes/pathways to the synthesis/breakdown/transformation of materials in service of humans

27
Q

benefits of using microorganisms in biotechnology

A
  • Inexpensive
  • simple requirement
  • small space requirements
  • Diverse groups within microorganisms
  • No ethical issues
  • Short life cycle so replicate quickly
  • Easy to genetically modify.
28
Q

Commercial uses of microorganisms in indirect food production
Baking

A
  • Yeast is mixed with sugar and water to respire aerobically
  • carbon dioxide produced makes bread rise
  • When it is cooked in a hot oven, carbon dioxide bubbles expand, so bread rises more and yeast cells are killed.
29
Q

Commercial uses of microorganisms in indirect food production
Brewing

A
  • yeast respires anaerobically to produce ethanol
  • GM yeasts ferment at lower than 20-28°C, cheaper
  • yeast clumps together (flocculates) and sinks at the end of the process, leaving beer clear
  • malting, barley germinated producing enzymes that break starch to sugars, seeds are heated and killed but enzymes produce malt
  • mashing, malt mixed with hot water and enzymes break down starches to produce wort, which is sterilised and cooled
  • fermentation, wort is inoculated with yeast, which is eventually inhibited by pH fall and ethanol
  • maturation
  • beer is filtered, pasteurised and bottled or canned with CO2
30
Q

Commercial uses of microorganisms in indirect food production
Cheese making

A
  • Bacteria feed on lactose in the milk, changing the texture and taste and inhibiting the growth of bacteria which make milk go off
  • Milk is pasteurised to kill off most natural bacteria and homogenised (fat droplets evenly distributed)
  • Mixed with bacteria cultures, and sometimes chymosin enzyme
  • kept until it separates into curds and whey
  • whey is used for animal feeds
  • curds are cut, cooked, pressed and matured
  • Bacteria continue to act when the cheese is maturing.
31
Q

Commercial uses of microorganisms in indirect food production
Yoghurt making

A
  • Bacteria, often lactobacillus bulgaricus (forms ethanal) and streptococcus thermophilius (forms lactic acid) produce extracellular polymers, thickening the yoghurt
  • Skimmed milk powder is added to milk mixture and pasteurised, homogenised and cooled
    -Milk is mix ed with 1:1 of the two bacteria and incubated at 45 degrees for four to five hours.
32
Q

Commercial uses of microorganisms in direct food production
Single-cell protein (SCP)

A
  • potential protein shortages, so scientists are developing more ways of using microorganisms to directly produce protein we can eat
  • Quorn = fusarium venetatum fungus
  • single celled fungus grown in large fermenters using glucose syrup as a food source
  • protein is combined with albumin (egg white), compressed and formed into meat substitutes
  • suitable for vegetarians, high in protein, low in fat
  • SCPs also being used to feed livestock
33
Q

advantages of using microorganisms in direct food production

A
  • reproduce quickly and produce protein faster than animals or plants
  • high protein content with little fat
  • utilise wide range of waste materials to feed fungus
  • can be genetically modified to produce a required protein
  • not dependent on weather, breeding cycles etc.
  • constant supply and can be altered to meet demand
  • no welfare issues
  • can be made to taste like anything
34
Q

disadvantages of using microorganisms in direct food production

A
  • can produce toxins if optimum conditions are not maintained
  • have to be separated from nutrient broth and processed to make food
  • need sterile, carefully controlled conditions, adding to the cost
  • many people have concerns with eating GM food and eating microorganisms fed off waste
  • protein has to be purified
  • has little flavour, needs additives
35
Q

insulin from animals

A
  • extracted from pancreas of animals slaughtered for meat
  • supply depended on demand for meat, so was erratic
  • peak activity is several hours after injection, so difficult to plan
  • ethical reasons/faith group objections
  • allergies to impure animal insulin
36
Q

producing penicillin (p. chrysogenum)

A
  • needs relatively high oxygen levels and a rich nutrient medium to grow well
  • sensitive to pH and temperature
  • semi-continuous batch process is used
  • in the first stage of the production, the fungus grows, in the second stage it produces penicillin
  • drug is extracted and purified
  • process uses relatively small bioreactors and continuously stirred to maintain high levels of oxygenation
  • contains a buffer to maintain pH as 6.5
  • rich nutrient medium
  • bioreactors maintained at 25-27°C (through steam and cold water, steam also sterilises)
37
Q

Bioremediation

A
  • the use of living organisms to remediate (get back to a natural state) after a pollution or contamination event
  • microorganisms are usually used
  • use of organisms that naturally break down organic material released as pollutants such as sewage and crude oil into carbon dioxide and water. Microorganisms are supported to break down as much as possible e.g. by adding nutrients to the water at the site of an oil spill
  • use of GMOs to break down or accumulate contaminants that they would not normally encounter e.g. mercury contamination
38
Q

bacterial requirements

A
  • oxygen
  • warmth
  • nutrients (carbohydrates, amino acids, inorganic minerals)
  • water availability (for diffusion)
39
Q

Binary fission

A
  • How prokaryotic organisms divide and reproduce
  • very rapid under ideal conditions
  • circular DNA (main genetic material) and plasmid(s) replicate
  • cell enlarges, replication of additional organelles
  • circular DNA strands move to opposite poles of the cell and new cell walls begin to form
  • cytokinesis, cytoplasm fully divides, 2 new daughter cells produced which have identical circular DNA but may have different combinations of plasmids
  • cytoplasm begins to divide
40
Q

Aseptic technique

A
  • heating inoculation loop to sterilise, avoiding contamination of bacteria
  • liftin lid of petri dish only slightly, preventing contamination from airborne microorganisms
  • keeping equipment in hand to reduce the rick of contamination if placed on surfaces
  • providing nutrient agar to provide conditions required for bacterial growth
  • incubating at 25°C so enough warmth for growth but not enough to select for human pathogens
  • sellotaping lid across top to select for aerobic not anaerobic bacteria
  • working close to a bunsen burner to reduce contamination from airborne microorganisms
41
Q

Bacterial growth curve

A
  • bacterial growth somewhere with finite resources/space
    Lag phase
  • acclimation to a new environment
  • may be synthesising new enzymes to digest new food source
  • reproduction not at maximum rate
    Log phase
  • exponential growth in population
  • rate of reproduction at/close to maximum
  • optimal conditions (space, nutrient availability, little waste product build up, low competition)
    Stationary phase
  • net growth is zero, rate of death is same as rate of reproduction
  • increased competition, limited resources, build up of waste products
    Death phase
  • exponential decrease in population
  • reproduction rate almost ceased, death rate increasing
  • lack of nutrients and oxygen, changes in pH, waste product build up
42
Q

Continuous culture

A

nutrients are continually added and the product and waste are regularly harvested. This keeps the culture in the log phase of growth. This maximises production of primary metabolites or of the microorganisms themselves. e.g. ethanol

43
Q

Batch culture

A

the fermenter is set up with a fixed quantity of nutrients and is then left. The culture reaches the stationary phase, when secondary metabolites are made, and then the product is harvested. e.g. antibiotics

44
Q

controlling bioreactors

A
  • temperature, heating and/or cooling system linked to temperature sensors ad a negative feedback system to maintain optimal temperature
  • nutrients and oxygen, added in controlled amounts when probes indicate it is dropping
  • a mixing mechanism to microorganisms receive enough food and oxygen
  • sealed and aseptic to avoid contamination
45
Q

primary metabolites

A
  • essential to normal functioning of the microorganism
  • produced during active growth phase
  • e.g. ethanol, ethanoic acid, amino acids
46
Q

secondary metabolites

A
  • not essential to normal functioning of the microorganism
  • produced during stationary phase
  • e.g. antibiotics, enzymes, pigments, toxins
47
Q

advantages of using isolated enzymes instead of the whole organism

A
  • less wasteful, microbes use up substrate producing biomass, enzymes do not
  • more efficient, isolated enzymes work at much higher concentrations
  • more specific, no unwanted enzymes present so no unwanted side reactions
  • maximise efficiency, optimum conditions differ from that of microbes
  • less downstream processing as pure product produces, so less expensive
48
Q

advantages of using extracellular enzymes in industrial processes

A
  • easier to isolate and use as no separation required
  • relatively few extracellular enzymes produced so easy to identify and isolate
  • more robust (adapted to greater variation in conditions)
49
Q

use of intracellular enzymes in industrial processes

A
  • harder to isolate but wide range of enzymes
  • often requirement outweighs disadvantages
  • e.g. glucose oxidase (food treatment), asparigase (cancer treatment), penicillin acylase (penicillin conversion)
50
Q

what are immobilised enzymes

A
  • enzymes used in industrial processes are attached to an inert support system over which the substrate and product passes
  • enzymes are held stationary during the process so do not contaminate then end product and can be recovered from the reaction mixture and used again
51
Q

advantages of using immobilised enzymes

A
  • reusable so cheaper
  • easily separated from reactants and products so less downstream processing
  • more reliable, insoluble support provides a stable environment
  • less prone to denaturation and work over a wide range of temperatures
  • conditions in bioreactors can be altered to use enzymes continuously
52
Q

disadvantages of using immobilised enzymes

A
  • process of immobilising enzymes may reduce efficiency
  • higher initial costs due to materials (immobilised enzymes more expensive)
  • higher initial investment cost of specialised bioreactor
  • complex bioreactors may cause more technical issues
  • may be limits on diffusion of substrate into complex
53
Q

immobilising enzymes through surface immobilisation, adsorption to inorganic carriers

A
  • enzymes adsorbed on to inorganic carriers e.g. cellulose, silica, carbon nanotubes, polyacrylamide gel
  • simple and cheap to do
  • can be used with many different processes
  • enzymes very accessible to substrate
  • activity virtually unchanged
  • enzymes can be lost from matrix relatively easily
54
Q

immobilising enzymes through surface immobilisation, covalent or ionic bonding to inorganic carriers

A
  • covalent bonding of enzymes to carriers with amino, carboxyl, hydroxyl groups
  • ionic bonding of enzymes to polysaccharides such as cellulose, synthetic polymers
  • cost varies
  • enzymes strongly bound so unlikely to be lost
  • enzymes very accessible to substrate
  • pH and substrate concentration often have little effect on enzyme activity
  • active site of the enzyme may be modified in the process, making it less effective
55
Q

immobilising enzymes through entrapment in a matrix

A
  • e.g. polysaccharides, gelatin, activated carbon
  • widely applicable in different processes
  • relatively expensive
  • can be difficult to entrap
  • diffusion to the substrate to and product from the active site can be slow and hold up the reaction
  • effect of entrapment on enzyme activity very variable depending on matrix
56
Q

immobilising enzymes through entrapment in microcapsules or behind a semi-permeable membrane

A
  • e.g. polymer-based semi-permeable membranes
  • relatively simple to do
  • relatively small effect on enzyme activity
  • widely applicable to different processes
  • relatively expensive
  • diffusion of the substrate to and product from the active site can be slow and hold up the reaction
57
Q

using immobilised microorganisms

A
  • avoids time consuming and expensive process of extracting the pure enzyme and immobilising before the process starts
  • organisms need food, oxygen and carefully controlled environments to work at their optimum rate
58
Q

using immobilised enzymes, penicillin acylase

A
  • catalyses naturally produced penicillin to semi-synthetic penicillin
  • resistant bacteria still vulnerable to semi-synthetic penicillins
59
Q

using immobilised enzymes, glucose isomerase

A
  • catalyses glucose into fructose
  • fructose is sweeter and used widely as a sweetener
  • glucose can be produced from cheap starch-rich plant material
60
Q

using immobilised enzymes, lactase

A
  • catalyses lactose into glucose and galactose
  • hydrolyses lactose to produce lactose free milk for cats and lactose intolerant humans
61
Q

using immobilised enzymes, amino acylase

A
  • catalyses the production of pure samples of L-amino acids used in the production of pharmaceuticals, organic chemicals, cosmetics and food
62
Q

using immobilised enzymes, glucoamylase

A
  • amylase enzymes break starch into short chain polymers (dextrins)
  • glucoamylase catalyses the break down dextrins into glucose syrup
  • glucose syrup is widely used in processed foods as a sweetener and thickener
63
Q

using immobilised enzymes, nitrile hydratase

A
  • catalyses acrylonitrite into acrylamide
  • acrylamide used in plastic production
  • used to be done with sulfuric acid and copper catalyst but nitrile hydratase is more effective with a higher yield

A-level Biology (24 decks)

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