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BIOLOGY A LEVEL > CHAPTER 22 - CLONING AND BIOTECHNOLOGY > Flashcards

CHAPTER 22 - CLONING AND BIOTECHNOLOGY Flashcards

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1
Q

What is vegetative propogation

A

A form of natural cloning in plants, a structure which develops into a fully differentiated plant, identical to the parent

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2
Q

What are some examples of natural plant cloning

A

Bulbs - leaf bases which swell with stored food from photosynthesis

Runners - from plants like strawberries where a lateral stem grows away from the parent plant and roots develop underneath, eventually creating an independent plant

Rhizomes - a specialised horizontal stem running underground, with stored food

Stem tubers - eg. potato buds on storage organ develop to produce new shoots

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3
Q

How are natural clones carried out in horticulture

A

,Bulbs are split up,

removing young plants from runners

Cutting up rhizomes

Taking a cutting of a plant, with rooting hormone (which is quicker than just using a seed)

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4
Q

What are perennating organs and how are they involved in cloning and survival

A

Organ which contains stored food from photosynthesis e.g., potato

cloning – new bud/plants
may arise from the organ identical to original plant

allows plant to survive adverse conditions

and produce a new shoot

using energy from food store

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5
Q

Explain the advantages and disadvantages of propagating crop plants by cutting over using seeds

A

Cuttings – genetically identical to parent so likely to produce good crops

often shorter time from planting to crop

reliable

don’t have to buy in

can use own plants

Seeds – have genetic variation so more variability in quality of crop

but are more likely to
withstand disease of changes in circumstances

take time and right conditions to germinate and grow to maturity

in some cases can collect seed and reuse for next planting but don’t always get the same quality

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6
Q

Suggest why it is important to describe clones as genetically identical to their parent rather than simply identical - and why even this may not always be true

A

Genetically identical because parts of the same plant

but eventually form will depend on
growing conditions – levels of light, water, temperature etc.

identical suggests appearance is the
same

cloned plants may not be identical because a mutation may take place in stem cells of meristems

changing pattern of growth in the plant

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7
Q

When is micropropogation used

A

When a desirable plant:
Doesnt readily produce seeds
Doesnt respond well to natural cloning
Is very rare
Genetically modified or selectively bred with difficulty
Required to be pathogen-free by growers

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8
Q

What are the basic principles of micropropogation and tissue culture

A

Take a small sample of tissue from the plant you want to lone - meristem from shoot or root tips that is virus free

Sterilising sample, using agents like bleach or ethanol

Explant is then placed in sterile culture medium containing balance of plant hormones, proliferating and forming a mass of identical cells called a callus is divided into individual cells or clumps, transferred into a new culture medium containing a different mix of hormones, stimulating development of tiny genetically identical plantlets

These are potted in compost to grow into small plants

Young plants are planted out to grow and produce a crop

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9
Q

What are the advantages for micropropogation

A

Allows for rapid production of large number of plants with high yield of crops and known genetic makeup

Culturing meristem tissue produces disease-free plants

It makes it possible it produce disease-free plants

Produces viable number of plants are genetic modification of plant cells

Produces very large number of new plants which are seedless and therefore sterile (eg. banana and grape)

It provides a way of reliably increasing the numbers of rare or endangered plants

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10
Q

Arguments against micropropagation

A

Produces monoculture - all susceptible to same disease or change of environment

Relatively expensive process with skilled workers

Vulnerable to infection during production process

If source material is infected, all clones will be infected

Large number of plants can be lost during the process

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11
Q

What is the potential of natural cloning for saving important crops such as the banana against disease

A

Advantages
relatively easy
relatively cheap and readily available
history of use

Disadvantages
any disease in parent plant transferred with cutting etc.
limit to number of new
plants that can be formed so cannot keep up with demand if there is a major threat to crop
still produces clones

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12
Q

What is the potential of micropropagation for saving important crops against disease in contrast to natural cloning? give arguments for and against

A

Advantages can produce disease-free plants

can produce plants engineered to be resistant to
disease

can produce almost limitless numbers of plants fast

Disadvantages
relatively expensive
needs some infrastructure
still produces clones

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13
Q

How does natural animal cloning occur in invertebrates

A

Some animals eg. starfish, can regenerate entire animals from fragments of the original if they are damaged

Flatworms and sponges fragment and form new identical animals as part of their normal reproductive process

Hydra produce small buds on the side of their body which will develop into genetically identical clones

Some insects can produce offspring without mating - although high level of mutation so these arent true clones

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14
Q

How does natural animal cloning occur in vertebrates

A

Formation of monozygotic twins, when the early embryo splits to form two seperate embryos - differences occur in nutrition and position in uterus

Some female amphibians and reptiles will produce offspring when no male is available - but they are often male so they arent clones, but all of the genetic material is from the mother

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15
Q

How are invertebrates cloned

A

Liquidising a sponge or chopping up a starfish and a new animal will regenerate from most of the fragments

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16
Q

What are the two methods of vertebrate cloning

A

Artificial twining
Somatic cell nuclear transfer (SCNT)

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17
Q

Describe the process of artificial twinning, using cattle as an example

A

Cow with desirable traits is treated with hormones so she super-ovulates, releasing more mature ova than normal

Ova may be fertilised naturally or by artificial insemination, by a bull with good traits, then embryo is flushed out of the nucleus

Or mature eggs are removed and fertilised by top-quality bull semen in the lab

Usually before or around day 6 - cells are totipotent, and early embryo is split to produce several smaller embryos - each capable of producing a healthy full-term calf

Each of the split embryos is grown in the lab for a few days to ensure healthy growth before they are implanted into a surrogate mother

Embryos develop into foetuses and are born normally, so a number of identical cloned animals are produced by different mothers

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18
Q

Describe the stages of Somatic cell nuclear transfer

A

Nucleus is removed from a somatic cell of an adult animal

Nucleus is removed from a mature ovum harvested from a different female of the same species (it is enucleated)

The nucleus from adult somatic cell is placed into enucleated ovum and given a mild electric shock so it fuses and begins to divide

Embryo that develops is transferred into the uterus of a third animal, where it develops to term

New animal is a clone of the animal from which the original somatic cell is derived, but mitochondrial DNA will come from egg cell

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19
Q

What are the arguments for animal cloning

A

Produces more offspring than normal reproduction

Allows success of passing on desirable genes

Allows scientist to replicate a specific animal eg, top class race horse

Enables rare or endangered or extinct animals to reproduce

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20
Q

Arguments against animal cloning

A

Inefficient process - most animals take any eggs to produce a single cloned offspring

Cloned embryos fail to develop and miscarry or produce malformed offspring

Many animals produced by cloning have shortened lifespans

Unsuccessful in increasing populations of rare organisms or to bring back extinct animals

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21
Q

How is artificial twinning different from natural twinning

A

Natural twinning early embryo splits

and two fetuses go on to develop

from the two halves
of divided embryo

Artificial twinning split in early embryo is produced manually

number of identical embryos may be replaced in surrogate mothers

to produce a number of identical high
quality animals

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22
Q

The evidence suggests that monozygotic twins do not occur naturally in cattle. Suggest ways in which this might be investigated

A

Observing births and recoding twin births when animals appear the same

genetic testing of any
twin cattle of the same gender

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23
Q

Explain the similarities between artificial twinning and SCNT

A

Both processes involve removing eggs from an animal

both involve surrogate parents

both potentially produce a number of genetically identical organisms

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24
Q

Explain the differences between artificial twinning and SCNT

A

In twinning either gametes meet outside the body

and early embryo develops before being split

or early embryos flushed from the mother

egg cell contributes all maternal DNA

embryos produced from gametes

embryos genetically related to two parents

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25
Q

What is biotechnology

A

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

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26
Q

What are some reasons why using microorganisms are ideal

A

No welfare issues to consider

Enormous range of microorganisms capable of carrying out many different reactions

Genetic engineering allows manipulation of microorganisms to carry out desirable reactions eg. production of human insulin

Short life cycle and rapid growth rate

Simple nutrient requirements and is often cheap

Low temperature conditions

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27
Q

What are some examples of indirect microorganism action on food production

A

Baking - yeast
Brewing - yeast
Cheese making - bacteria
Yoghurt making - bacteria

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28
Q

What are some examples of direct microorganism action on food production

A

Eating fungi eg. mushrooms

Producing Single-cell protein eg. Quorn from a fungus and fermenter and added with egg whites

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29
Q

Advantages of using microorganisms to produce human food

A

Reproduce fast and produce protein faster than animals or plants

High protein with little fat content

Can use variety of waste materials, including animal and human waste

Genetically modified to produce protein required

Production of microorganisms isnt present on weather or breeding cycles

No welfare issues when growing

Made to taste like anything

30
Q

Disadvantages of using microorganisms to produce human food

A

Some microorganisms can also produce toxins if not maintained in optimum conditions

Microorganisms have to be separated to make food

Involve GM organisms and many people have concerns eating GM food

Protein has to be purified

Dislike the thought of eating microorganisms grown on waste

Has little natural flavour - needs additives

31
Q

Compare the way yeast is used in the process of baking and brewing

A

Baking:
Mixed with sugar and water
Respires aerobically
Carbon dioxide produced used to
make bread rise
Yeast killed by heating as bread cooks
Takes a couple of hours

Brewing:
Mixed with malted barley and hot water
Respiration (fermentation ) Continues for days in anaerobic
conditions (1);
Ethanol produced as waste product Yeast eventually inhibited (not killed) by rising pH
Build-up of ethanol and lack of oxygen

32
Q

Why is milk pasteurised before being used commercially to make cheese and yoghurt

A

To destroy bacteria that would make it go bad rapidly

or cause diseases such as TB

33
Q

Why is milk homogenised before being used commercially to make cheese and yoghurt

A

The fat droplets are spread evenly through milk so cream doesn’t separate out

and creates a uniform product

34
Q

Give two important differences between the production processes of cheese and yoghurt

A

Cheese whole milk used

bacteria used to separate the curds from the whey

changing texture, and bacteria ripen or mature the cheese in controlled slow reactions at low temperatures to change taste

out-compete bacteria that would make the cheese go bad

takes weeks, months
or years

can last for years

Yoghurt skimmed milk powder added to milk to enrich it

specific bacteria added and incubated at 45°C for 4–5 hours to produce extracellular polymers that
give the texture to yoghurt

lasts 2–3 weeks in a fridge

35
Q

What are the different approaches to bioremediation

A

Using natural organisms -
Many microorganisms naturally break down organic material producing carbon dioxide and water

GM organisms -
Breakdown or accumulation of contaminants which they wouldnt usually encounter

36
Q

What conditions are needed to produce penicillin

A

Small Fermenters
Mixture continuously stirred to keep oxygenated
Rich nutrient medium
Growth medium contains a buffer to maintain pH at around 6.5
medium temperature

37
Q

What was the main difference between the use of fungi to produce penicillin and the use of bacteria to produce human insulin

A

Fungi produce penicillin naturally

bacteria genetically engineered/modified to produce human insulin

38
Q

What is bioremediation? why it is often carried out on the site of contamination

A

Use of microorganisms or plants to break down pollutants and contaminants in soil or water

often carried out on site
because area of contamination may be very large so not practical to
remove contaminated material/too expensive to remove contaminated material

organisms involved in bioremediation grown and break down contaminants in situ

living organisms so they
grow and spread

may be harvested and contaminants retrieved

39
Q

What are the risks of using microorganisms as a culture

A

There is always a risk of mutation taking place making the strain pathogenic

There may be contamination with pathogenic microorganisms

40
Q

What are the processes by which bacteria must be added

A

Inoculating broth
Inoculating agar

41
Q

How do you make inoculating broth

A

Make suspension of the bacteria to be grown

Mix a known volume with the sterile nutrient broth in the flask

Stopper flask with cotton wool to prevent contamination from the air

Incubate at a suitable temperature shaking regularly to aerate the broth providing oxygen for the growing bacteria

42
Q

How do inoculating agar prepared

A

Wire inoculating loop must be sterilised by holding it in a bunsen flame until it glows red hot

Dip the sterilised loop in the bacterial suspension, remove lid of petri dish and make a zig-zag streak across the surface of the agar

Replace lid of petri dish, held down and sealed with tape, but not completely so oxygen can still get in

43
Q

What are the phases of growth in bacterial colonies

A

Lag phase - when bacteria are adapting to their new environment

Exponential phase - Rate of bacterial reproduction is close to or at its theoretical maximum

Stationary phase - total growth is 0 (in dynamic equilibrium)

decline phase - reproduction has ceased and rate of death of cells is increasing

44
Q

What are the several limiting factors which prevent exponential growth

A

Nutrients available
Oxygen levels
Temperature
Build-up of waste
Change in pH

45
Q

Compare the processes of culturing bacteria in broth and on agar

A

Both provide nutrients, suitable pH, moisture etc

both need to be maintained at optimum
temperature for growth

both must be kept sterile until inoculated with microorganisms

both can be shaken at intervals to aerate it

agar plates remain closed once made up

broth is mixed
with known volumes of culture medium

agar plates inoculated using sterile wire loop and culture
medium

numbers in broth counted using turbidity, serial dilutions, and microscope graticules

numbers on agar calculated using colony counting

46
Q

Why are there such clear differences between the theoretical growth curve of a bacterial colony and the actual growth curve in a closed culture

A

In large closed culture nothing gets in or out

initially, growth can be at theoretical rate as no
factors are limiting

as culture continues, numbers increase, food and oxygen are used up and
waste products build up often affecting pH

microorganisms run out of food or oxygen, are
inactivated by pH changes affecting enzymes or poisoned by waste products

so whilst theoretical
growth curve is exponential, real growth curve reaches a peak, plateaus, and declines

47
Q

Explain why vinegar is a very good preservative

A

Vinegar is ethanoic acid therefore has a low pH

and inhibits bacterial growth

48
Q

Explain why food eventually goes bad in the fridge

A

As temperatures fall bacteria growth slows but does not stop

so in fridge bacteria grow slowly
and eventually destroy food

49
Q

Explain why in the northern hemisphere, material placed in a compost heap rots down much faster in August than it does in december

A

Reactions in bacteria and fungi that act as decomposers affected by temperature

in August
temperatures relatively high so decomposition reactions relatively fast. In December, the
temperatures are much cooler so slower reactions in decomposers and rotting slower

50
Q

What is primary and secondary metabolites from microorganism culture

A

Primary are the substances wanted which form the essential functioning of the microorganism

Secondary metabolites are non essential for growth, but still used by the cells, eg. pigments and toxins against herbivores. Extracted in bioprocess eg. penicillin and other antibiotics

51
Q

What is batch fermentation

A

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 ceases, carries out biochemical changes to form desired end products

Process is stopped before death phase and the products are harvested

52
Q

How does continuous culture work

A

Microorganisms are inoculated into sterile nutrieinnt medium and start to grow

Sterile nutrient medium is added continually to the culture once it reaches the exponential point of growth

Culture broth is continually removed, the medium, waste products, microorganisms, and product - keeping the culture volume in the bioreactor constant

53
Q

What factors need to be controlled in bioreactors

A

Temperature
Nutrients and oxygen
Thickness
Asepsis

54
Q

What is the structure of a bioreactor

A

page 600

55
Q

Bioreactors may run batch or continuous process. What is the difference

A

Continuous processes run continuously once fermentation is started

sterile nutrient medium
added continuously once culture is growing exponentially

culture broth continually removed so product can be processed and culture volume remains the same

Batch process everything added
at beginning in fixed volume of medium

nutrients used up and microorganisms, products, and
waste products build up

may be stationary phase when secondary metabolites formed, process
stopped, products extracted, reactor cleaned, and new process begun

56
Q

Choose three factors which need to be controlled in a bioreactor to give the maximum yield of product and for each explain why it is important and how it might be controlled

A

Temperature
if temperature too low microorganisms will not grow
quickly enough, too high and enzymes will start to denature and microorganisms are inhibited or
destroyed. Bioreactors often have a heating and/or a cooling system linked to temperature sensors
and a negative feedback system to maintain optimum conditions.

Nutrients
if microorganisms use up
food supply they will start to die off so need a mechanism to keep food supplied, nutrient 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.

Oxygen
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.

pH
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.

57
Q

Why are immobilised enzymes so efficient

A

Less wasteful - do not produce biomass

More efficient - isolated enzymes work at much higher concentrations

More specific - no unwanted enzymes present, no wasteful side reactions

Maximise efficiency - can be given ideal conditions for maximum product formation as opposed to ideal condition for organism

Less downstream processing - so it is therefore cheaper

58
Q

Why are extracellular enzymes cheaper and easier to use for isolating enzymes than intracellular

A

Secreted, making them easy to isolate and use

Microorganims produce few extracellular enzymes, so it is easy to identify, but produce hundreds of intracellular enzymes

More robust than intracellular, as conditions outside a cell are less tightly controlled

59
Q

What are some advantages of using immobilised enzymes

A

Immobilised enzymes can be reused - so cheaper

Easily separated from the reactants and products of the reaction

More reliable - higher control over the process

Greater temperature tolerance

Easy manipulation

60
Q

What are some disadvantages of using immobilised enzymes

A

Reduced efficiency by immobilising an enzyme by changing its active site

Higher initial cost of materials

Higher initial cost of bioreactor

More technical issues

61
Q

What is adsorption surface immobilisation, and its advantages and disadvantages

A

Adsorption to inorganic carrier eg. silica

+ves:
Simple, cheap
can be used for many processes
Accessible to substrate and activity is almost unchanged

-ves:
enzymes can be lost from the matrix fairly easily
(pg 603)

62
Q

What is covalent surface immobilisation, and its advantages and disadvantages

A

Covalent or ionic bonding to an inorganic carrier, polysaccharide or polymer

+ves:
Cost varies,
Strongly bound so unlikely to be lost
Enzymes accessible to substrate
pH and substrate conc often have little effect on activity

-ves:
Cost varies
Active site of the enzyme may be modified
(pg 603)

63
Q

What is entrapment in a matrix, and its advantages and disadvantages

A

Entrapment in a matrix eg. gelatin

+ves:
Widely applicable to different processes

-ves:
May be expensive
Can be difficult to entrap
Diffusion to the substrate to and product from active site
Variable enzyme activity depending on matrix
(pg 603)

64
Q

What is entrapment in a microcapsule, and its advantages and disadvantages

A

Entrapment - membrane entrapped in a semipermeable membrane eg. a polymer

+ves:
Simple to do
Small effect on activity
Widely applicable to different processes

-ves:
Expensive
Diffusion of the substrate to and product from active site can be slow and hold up the reaction
(pg 603)

65
Q

What are some examples of immobilised enzyme products

A

Penicillin
Fructose
lactose free milk
L-amino acids
Dextrins
Plastics

66
Q

What is meant by an immobilised enzyme

A

Enzymes attached to an inert support system

over which the substrate passes and is converted to product

67
Q

What are the main advantages of immobilised enzymes over whole microorganisms

A

More efficient

more specific; can optimise conditions for specific enzyme

less downstream processing

68
Q

What are the main advantages of immobilised enzymes over free enzymes

A

Can be reused

easily separated from reactants and products

more reliable as control over process

greater temperature tolerance

69
Q

Summarise the ways in which enzymes are immobilised

A

Surface immobilisation – absorption onto inorganic carriers

covalent or ionic bonding onto inorganic carriers

entrapment in a matrix

entrapment in membrane bound microcapsule

70
Q

How can immobilisation:
Increase the effectiveness of an enzyme

A

Enzymes are accessible to substrates

allow continuous production by a continuous flow of medium over the enzyme

conditions can be very tightly controlled over the enzyme beds

changes in pH and temperature have less effect

71
Q

How can immobilisation:
decrease the effectiveness of an enzyme

A

Immobilising an enzyme may affect its ability to catalyse a reaction

diffusion of substrate to and from active site of enzyme can be inhibited

by immobilising matrix or capsule and so slow reaction

in surface immobilisation enzymes may be lost from matrix relatively easil

BIOLOGY A LEVEL (24 decks)

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