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A2 Biology > 6.2.1 - Cloning and Biotechnology > Flashcards

6.2.1 - Cloning and Biotechnology Flashcards

1
Q

Define cloning

A

Cloning is a method of producing genetically identical offspring by asexual reproduction

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2
Q

What is vegetative propagation

A

Natural cloning in flowering plants

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3
Q

Describe natural plant cloning in bulbs e.g. daffodil

A

The leaf bases swell with stored food from photosynthesis. Buds form internally which develop into new shoots and new plants in the next growing season.

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4
Q

Describe natural plant cloning in runners e.g. strawberry or spider plant.

A

A lateral stem grows away from parent plant and roots develop where runner touches the plant. A new plant develops - the runner eventually withers away leaving the new individual independent.

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5
Q

Describe natural plant cloning in rhizomes e.g. marram grass.

A

A rhizome is a specialised horizontal stem running underground, often swollen with stored food. Buds develop and form new vertical shoots which become independent plants.

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6
Q

Describe natural plant cloning in stem tubers e.g. potato.

A

The tip of an underground stem becomes swollen with stored food to form a tuber or storage organ. Buds on the storage organ develop to produce new shoots.

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7
Q

Describe how cuttings are taken.

A

Short sections of stems are taken and planted either directly in the ground or in pots. Then, rooting hormone is applied to the base of a cutting to encourage growth of new roots

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8
Q

What are the advantages of using cuttings over seeds?

A
  • Much faster
  • Offspring is genetically identical
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9
Q

What is the main disadvantage of the use of cuttings over the use of seeds?

A

There is a lack of genetic variation in the offspring, which could be problematic if any new disease or pest appears.

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10
Q

What is micropropagation?

A

Micropropagation is the process of making large numbers of genetically identical offspring from a single parent using tissue culture techniques.

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11
Q

When is micropropagation using tissue culture used?

A

When a desirable plant:
- does not readily produce seeds
- does not respond well to natural cloning
- is very rare
- has been GMed or selectively bred with difficulty.
- is required to be pathogen-free by growers

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12
Q

Describe how tissue culture can be carried out (Part 1)

A
  • Take a small sample of tissue from the desired plant. The meristem tissue from shoot tips and axial buds is often dissected out in sterile conditions to avoid contamination
  • Sterilise sample by immersing in ethanol and wash it off. Material removed from plant is called the explant
  • Place explant in a sterile culture medium containing balance of hormones which stimulate mitosis. The cells proliferate forming a mass of identical cells known as a callus.
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13
Q

Describe how tissue culture can be carried out (Part 2)

A
  • 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 tiny, genetically identical plantlets.
  • The plantlets are potted into compost where they grow into small plants
  • Young plants are planted out to grow and produce a crop.
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14
Q

Give advantages of micropropagation.

A

Allows rapid production of many plants
Culturing meristem produces disease-free plants
Can produce viable numbers of EM plants.
Can grow plants that are generally relatively infertile or difficult to grow from seed.
Reliably increases numbers of rare or endangered plants.

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15
Q

Disadvantages of micropropagation

A

Produces monoculture
Expensive and requires skilled workers.
Explants and plantlets are vulnerable to infection during production process
If source is infected, all clones are infected.
Large numbers of new plants may be lost in the process.

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16
Q

Describe natural cloning in vertebrates

A

The main form of vertebrate cloning is formation of monozygotic twins. The early embryo splits to form two separate embryos.
Some female amphibians and reptiles will produce offspring when no male is available. The offspring are often male rather than female, so they are not clones of their mother, yet all of their genetic material arises from her.

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17
Q

What is artificial twinning?

A

After an egg is fertilised, it divides to form a ball of cells. Each of these individual cells is totipotent - it has the potential to form an entire new animal. As the cells continue to divide, the embryo becomes a hollow ball of cells. Soon after, the embryo can no longer divide successfully.
In artificial twinning, the split in the early embryo is produced manually.

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18
Q

What is artificial twinning?

A

After an egg is fertilised, it divides to form a ball of cells. Each of these individual cells is totipotent - it has the potential to form an entire new animal. As the cells continue to divide, the embryo becomes a hollow ball of cells. Soon after, the embryo can no longer divide successfully.
In artificial twinning, the split in the early embryo is produced manually.

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19
Q

Describe the stages of artificial twinning in cattle

A
  • A cow with desirable treated with hormones so she super-ovulates, releasing more mature ova than normal.
  • The ova may be fertilised naturally or by artificial insemination. The early embryos are gently flushed out of the uterus.
  • At day 6, while the cells are still totipotent, the cells of the early embryo are split to produce several smaller embryos, each able to growing on to form a healthy calf.
  • Each of the split embryos is grown in the lab for a few days to ensure all is well before it is implanted into a surrogate mother.
  • The embryos develop into foetuses and are produced by different mothers, but are identical clones.
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20
Q

What does this technology make it possible to do?

A

Greatly increase the numbers of offspring produced by the animals with the best genetic stock. Some of the embryos may be frozen. This allows the success of a particular animal to be assessed, and if the stock is good, remaining identical embryos can be implanted and brought to term.

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21
Q

What is somatic cell nuclear transfer?

A

It is possible to clone an adult animal, by taking the nucleus from an adult somatic cell and transferring it to an enucleated egg cell. A tiny electric shock is used to fuse the egg and nucleus, stimulate the combined cell to divide, and form an embryo that is a clone of the original adult.

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22
Q

Describe the process of somatic cell nuclear transfer

A
  • The nucleus is removed from a somatic cell of an adult animal.
  • The nucleus is removed from a mature ovum harvested from a different female animal of the same species.
  • The nucleus from the adult somatic cell is placed into the enucleated ovum and given a mild electric shock so it fuses and begins to divide. In some cases, the nucleus from the adult cell is not removed - it is placed next to the enucleated ovum and the two cells fuse and divide under the influence of the electric current.
  • The embryo that develops is transferred into the uterus of a third animal, where it develops to term.
  • The new animal is a clone of the animal from which the original somatic cell is derived.
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23
Q

What are the pros of animal cloning?

A
  • Artificial twinning enables high-yielding farm animals to produce many more offspring than normal reproduction.
  • Artificial twinning enables the success of a male animal at passing on desirable genes to be determined.
  • SCNT enables GM embryos to be replicated and to develop, giving many embryos from one engineering procedure. It is an important process in the production of therapeutic human proteins of genetically engineered farm animals.
  • SCNT enables scientists to clone specific animals.
  • SCNT has the potential to enable rare, endangered, or even extinct animals to be produced, in theory.
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24
Q

What are the cons of animal cloning?

A
  • SCNT is a very inefficient process
  • Many cloned animals fail to develop and miscarry or produce malformed offspring.
  • Many animals produced by cloning have shortened lifespans.
  • SCNT has been unsuccessful in increasing populations of rare organisms or allowing extinct species to be brought back to life.
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25
Q

What is biotechnology?

A

The application of biological organisms or enzymes to the synthesis, breakdown, or transformation of materials in the service of people

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26
Q

Why is using microorganisms useful?

A

No welfare issues, large range of microorganisms to use, genetic engineering is simple, microorganisms have short life spans, nutrient requirements of microorganisms are simple and cheap, and maintenance is cheap

27
Q

What are the advantages of using microorganisms to produce human food?

A
  • They reproduce fast and produce protein faster
  • Have high protein content with little fat
  • Can use a wide variety of waste materials
  • Can be GMed
  • Not dependent on weather, breeding
  • No welfare issues
  • Can be made to taste like anything
28
Q

What are the disadvantages of using microorganisms to produce human food?

A
  • Some microorganisms can also produce toxins at non-optimum conditions
  • Have to be separated from nutrient broth
  • Need sterile conditions
  • Many people don’t eat GM food
  • Protein has to be purified
  • Little natural flavour
29
Q

What conditions are required for penicillin production?

A
  • Uses small fermenters
  • Mixture is continuously stirred
  • Rich nutrient medium
  • Contains a buffer to maintain pH at 6.5
  • Bioreactors maintained at 25 degrees
30
Q

What is bioremediation?

A

The use of microorganisms to break down pollutants and contaminants in soil or in water

31
Q

Describe the approach to bioremediation using natural organisms

A

Many microorganisms naturally break down organic material producing CO2 and H2O. Soil and water pollutants are often biological. If the natural microorganisms are supported, they will break down and neutralise many contaminants.

32
Q

Describe the approach to bioremediation using GM organisms

A

Scientists are trying to develop GM bacteria which can break down or accumulate contaminants which they would not naturally encounter. The aim is to develop filters containing these bacteria to remove contaminants from sites.

33
Q

What happens once the agar or nutrient broth is prepared?

A

The bacteria must be added via inoculation

34
Q

Why must the correct health and safety procedures be followed when dealing with microorganisms?

A

There is always a risk of mutation, making strain pathogenic, and there may be contamination with pathogenic microorganisms rom the environment

35
Q

How is broth inoculated?

A
  1. Make a suspension of bacteria to be grown
  2. Mix a known volume with the sterile nutrient broth in the flask
  3. Stopper the flask with cotton wool
  4. Incubate at a suitable temperature, remembering to shake regularly tro aerate the broth
36
Q

How is agar inoculated?

A
  1. The wire loop must be sterilised by holding in a Bunsen flame until it glows red
  2. Dip the sterilised loop in the bacterial suspension. Remove the lid of the Petri dish and make a zig-zag streak across the surface of the agar.
  3. Replace the lid of the Petri dish. Hold it down with tape but not completely so oxygen can get in. Incubate upside-down at a suitable temperature
37
Q

Describe the stages of a live bacteria growth curve

A

Lag phase - when bacteria are adapting to their new environment
Log phase - when the rate of bacterial reproduction is at theoretical max
Stationary phase - when growth rate is 0
Decline phase - when reproduction has almost stopped and death rate is increasing

38
Q

What are limiting factors to growth in a culture of bacteria?

A
  • Nutrients available
  • Oxygen levels
  • Temperature
  • Build up of waste
  • pH change
39
Q

What are primary metabolites?

A

Substances that are formed as an essential part of the normal functioning of a microorganism

40
Q

What are secondary metabolites?

A

Substances that are not essential for normal growth, but are still used by cells.

41
Q

What are the main two ways of growing microorganisms?

A

Batch fermentation and continuous fermentation

42
Q

Describe batch fermentation

A
  • The microorganisms are inoculated into a fixed volume of medium.
  • As growth takes place, nutrients are used up and both new biomass and waste products build up
  • As the culture reaches the stationary phase, overall growth stops but during this phase the microorganisms carry out biochemical changes to form the desired end products
  • Process is stopped before the death phase and a new batch is started
43
Q

Describe continuous fermentation

A
  • Microorganisms are inoculated into the sterile nutrient medium and start to grow
  • Sterile nutrient medium is added to the culture continually once it reaches the exponential point of growth.
  • Culture broth is continually removed.
44
Q

What technique is generally used in industry?

A

Batch fertilisation or semi-continuous fertilisation

45
Q

How is temperature controlled in bioreactors?

A

Bioreactors often have a heating and cooling system linked to temperature sensors and a negative feedback system to maintain optimum conditions

46
Q

How are nutrients and oxygen controlled?

A

Oxygen and nutrient medium can be added in controlled amounts when probes or sample tests indicate the levels are dropping

47
Q

How is asepsis ensured?

A

Bioreactors are sealed, aseptic units.

48
Q

Why do bioreactors have mixing mechanisms?

A

To ensure that temperature, food, oxygen are evenly distributed

49
Q

What are the advantages of using isolated enzymes rather than whole organisms?

A
  • Less wasteful
  • More efficient
  • More specific
  • Maximise efficiency
  • Less downstream processing
50
Q

Why is it that extracellular enzymes are used rather than intracellular enzymes?

A
  • Extracellular enzymes are secreted, so easier to isolate
  • Extracellular enzymes are more robust
51
Q

What is the advantage of using intracellular enzymes?

A

Much larger range of intracellular enzymes compared to extracellular enzymes

52
Q

What are the advantages of using immobilised enzymes?

A
  • Can be reused
  • Easily separated from reactants and products
  • More reliable
  • Greater temperature tolerance
  • Ease of manipulation
53
Q

What are the disadvantages of using immobilised enzymes?

A
  • Reduced efficiency
  • Higher initial cost of materials
  • Higher initial costs of bioreactor
  • More technical issues
54
Q

What is surface immobilisation?

A

The adsorption to inorganic layers

55
Q

What are the advantages of surface immobilisation?

A
  • Simple and cheap to do
  • Can be used with many different processes
  • Enzymes very accessible to substrate and their activity is almost unchanged
56
Q

What are the disadvantages of surface immobilisation?

A

Enzymes can be lost from matrix relatively easily

57
Q

What are the advantages of surface immobilisation of covalent or ionic bonding to inorganic layers?

A
  • Enzymes strongly bound and therefore unlikely to be lost
  • Enzymes very accessible to substrate
  • pH and substrate concentration often have little effect of enzyme activity
58
Q

What are the disadvantages of surface immobilisation of covalent or ionic bonding to inorganic layers?

A
  • Cost varies
  • Active site of the enzyme may be modified in the process
59
Q

What are the advantages of matrix entrapment?

A
  • Widely applicable to different processes
60
Q

What are the disadvantages of matrix entrapment?

A
  • May be expensive
  • Can be difficult
  • Diffusion of substrate to and product from the active site can be slow
  • Effect of entrapment is very variable.
61
Q

What are the advantages of membrane entrapment?

A
  • Simple
  • Small effect on enzyme activity
  • Widely applicable to different processes
62
Q

What are the disadvantages of membrane entrapment?

A
  • Expensive
  • Diffusion of substrate to and product from the active site can be slow
63
Q

Give examples of the uses of immobilised enzymes

A
  • Semi-synthetic penicillins
  • Lactose free milk
  • Breakdown of starch to glucose syrup

A2 Biology (14 decks)

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