6.2.1 Cloning and biotechnology

Question 1

What is cloning?

Answer 1

-process of producing genetically identical cells/organisms from an existing organism

Question 2

Explain natural cloning(aka vegetative propagation)

Answer 2

-production of genetically identical plant clones from non-reproductive tissue i.e roots, stem, leaf
-type of asexual reproduction
-can help plants survive adverse conditions by cloning certain organs involved in food storage/ones that can remain dormant in soil

Question 3

Examples of vegetative propagation

Answer 3

-bulbs: act as underground food storage. new bulbs are able to develop from original bulb and form new shoots + plants
-runners/stolons: i.e strawberries/spider plants, lateral stem grows away from the parent plant + roots develop where the runner touches the ground–} develops a new plant and the runner eventually withers away
-rhizomes: i.e marram grass, specialised horizontal stem running underground away from the parent plant. buds develop and form new vertical shoots which become independent plants
-tubers: large underground plant storage that act as a food storage, buds/’eyes’ on the storage organ sprout to produce new shoots i.e potato

Question 4

Advantages of natural cloning

Answer 4

-conditions that are good for the parent are good for the offspring
-rapid–} population can increase quickly
-reproduction can be carried out with one parent

Question 5

Disadvantages of natural cloning

Answer 5

-offspring may become overcrowded (competition affects yield)
-lack of genetic diversity (unless mutations during DNA replication)
-selection not possible
-whole population susceptible to changes in the environment

Question 6

Uses of natural clones in horticulture

Answer 6

-used by farmers and gardeners to produce new plants
-i.e splitting up bulbs, removing young plants from runners, cutting up rhizomes
-can use grafting(joining shoot of one plant to the growing stem and root of another plant), can use layering(bending a stem of a growing plant downwards so it enters the soil + grows into a new plant)
-food crops are propagated by cloning i.e bananas, sugar cane
-can also take cuttings of plants

Question 7

Method to producing plant clones from cuttings

Answer 7

-use a scalpel to take a cutting between 5 and 10 cm long, from the end of stem of the parent plant
-remove the leaves from the lower end of the cutting, leaving just one at the tip
-dip the lower end of the cutting in rooting powder, which contains hormones that induce root formation
-plant the cutting in a pot containing a suitable growth medium
-provide the cutting with a warm and moist environment by covering the whole pot with a plastic bag
-when your cutting has formed its own roots and is strong enough, you can plant it elsewhere to continue growing

Question 8

What is tissue culture?

Answer 8

-used to clone plants artificially that don’t readily reproduce or are endangered/rare

Question 9

Method of tissue culture technique

Answer 9

-(stem) cells are taken from the original plant
-cells are sterilised to kill any microorganisms (i.e bacteria and fungi which compete for nutrients with the plant cells, which decrease their growth rate)
-cells are placed on a culture medium containing organic nutrients i.e glucose + aa’s, and a high conc of auxins. carried out under aseptic conditions
-cells proliferate, forming a mass of identical undifferentiated cells
-mass can be subdivided to produce lots of plant quickly
-when the cells have divided + grown into a small plant, they’re taken out of the medium and planted in soil–} develop into new plants genetically identical to original plant

Question 10

Explain micropropagation using tissue culture

Answer 10

-the process of making large numbers of genetically identical offspring from a single parent plant rapidly using tissue culture techniques
-cells are taken from developing cloned plants and sub cultured(grown on another fresh culture medium)- repeating this process creates large no. of clones
-used to produce plants when a desirable plant: doesn’t readily produce seeds, is rare, has been genetically modified or selectively bred with difficulty, is required to be ‘pathogen-free’
-extensively used in horticulture and agriculture

Question 11

Advantages of micropropagation

Answer 11

-allows for the rapid production of large numbers of plants with known genetic makeup which will yield good crops
-culturing meristem tissue produces disease-free plants
-makes it possible to produce viable numbers of plants after genetic modification of plant cells
-provides a way of producing very large numbers of new plants which are seedless and therefore sterile
-provides a way of growing plants which are naturally infertile/difficult to grow from seed
-provides a way of reliably increasing the numbers of rare/endangered plants

Question 12

Arguments against micropropagations

Answer 12

-produces a monoculture= many plants which are genetically identical–} all susceptible to the same diseases or changes in growing conditions
-expensive process
-if the source plant is infected with a virus, all of the clones will also be infected
-large numbers of new plants are lost during the process

Question 13

What is natural animal cloning?

Answer 13

-can be produced naturally as a result of sexual reproduction—} fertilised egg can split in the early stages of development into multiple embryos with the same genetic info
-these can develop as normal to produce genetically identical offspring i.e identical twins

Question 14

Natural cloning in invertebrates

Answer 14

-starfish can regenerate entire animals from fragments of damaged original
-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 develop into genetically identical clones

Question 15

Natural cloning in vertebrates

Answer 15

-formation of monozygotic twins: early embryo splits to form two separate embryos
-some female amphibians and reptiles reproduce asexually(however the offspring are often male so not a clone of the mother but share her genetic material)

Question 16

What is artificial embryo twinning?

Answer 16

-similar to what happens in natural cloning(when an early embryo splits and two foetuses go on
to develop from the two halves) except the split in the embryo is manual
-used by the farming community to produce the maximum offspring as the early embryo may be split into
more than two pieces and create a no. of identical offspring

Question 17

What are the stages of artificial twinning?

Answer 17

-an egg cell is extracted from a female cow and fertilised in a petri dish
-fertilised egg is left to divide at least once, forming an embryo in vitro(outside a living organism)
-the individual cells from the embryo are separated and each is put into a separate petri dish—} each cell divides and develops when the cells are still totipotent, forming an embryo in each dish
-embryos are implanted into female cows, which act as surrogate mothers
-embryos continue to develop inside the surrogate cows, and eventually genetically identical offspring are born

Question 18

Somatic cell nuclear transfer(SCNT)

Answer 18

-process of cloning an adult animal by taking the nucleus from an adult somatic
(body) cell and transferring it to an enucleated egg cell (an oocyte
which has had the nucleus removed)
-steps:
1) a somatic cell(one that isn’t reproductive) is taken from an animal and the nucleus is removed
2) an oocyte(immature egg cell) is taken from another sheep and its nucleus is removed to form an enucleated oocyte
3) the nucleus from the somatic cell is placed in the enucleated oocyte and given a mild electric shock so it fuses and begins to divide—} produces an embryo
4) embryo is then implanted into a surrogate mother and a new animal is formed which is the clone of the somatic cell animal(but the mitochondrial DNA will come from the egg cell)

Question 19

Uses of animal cloning

Answer 19

-scientists use cloned animals for research purposes i.e genetically identical so less variables for drug trials
-cloning can be used in agriculture so farmers can increase the no. of animals with desirable characteristics to breed from
-animals that have been genetically modified to produce a useful substance that they wouldn’t normally produce could be cloned i.e goat milk with beneficial protein
-cloning can be used to save endangered animals from extinction by cloning new individuals

Question 20

Arguments for animal cloning

Answer 20

-artificial twinning enables high-yielding farms to produce more offspring than normal reproduction
-desirable genetic characteristics are always passed on to clones(no independent assortment or crossing over, which generate genetic variation during meiosis)
-infertile animals can be reproduced
-SCNT enables GM embryos to be replicated and develop many embryos
-cloning helps develop new treatments for disease, which could mean less suffering for some people

Question 21

Arguments against animal cloning

Answer 21

-very difficult, time consuming and expensive
-undesirable characteristics are always passed on to clones, susceptible to the same diseases
-inefficient process= often takes many eggs to produce a single cloned offspring
-many animals produced by cloning have shortened lifespans, unethical
-use of cloned human embryos as a source of stem cells is controversial(embryos often get destroyed after stem cells are harvested)

Question 22

What is biotechnology and what are the most commonly used organisms used in it?

Answer 22

-the industrial use of living organisms to produce food, drugs and other products
-most commonly used organisms are fungi and bacteria because:
-easy to grow successfully any time of year(as long as they have the right temp, pH, nutrients, moisture levels + availability of gases)
-inexpensive to grow
-grow rapidly under ideal conditions due to short life cycle(products can be made quickly)
-can be genetically engineered to carry out reactions they wouldn’t normally do

Question 23

Uses of microorganisms in biotech: Indirect food production

Answer 23

-microorganisms have an indirect effect when being used to make food–} it is their actions on food that is important
- Baking: the microorganism yeast makes the bread rise by respiring anaerobically, CO2 produced by fermentation of sugars in the dough makes sure it doesn’t stay flat
- Brewing: yeast respires anaerobically using glucose from the grain it is added to i.e barley to produce ethanol and CO2(fermentation)
- Cheesemaking: lactic acid bacteria converts the lactose in milk into lactic acid(makes it sour and helps solidify), chymosin enzyme can also be extracted from yeast which clots the milk
- Yoghurt: lactic acid/ ethanal bacteria causes milk to clot and thicken(both types of bacteria produce extracellular polymers that make yoghurt smooth + thick)

Question 24

Uses of microorganisms in biotech: direct food production

Answer 24

-microorganisms can be used to directly produce protein you can eat
- Quorn(type of single-cell protein) is produced by a single celled fungus that is grown in large fermenters
:) suitable for vegetarians, high in protein and low in fat

Question 25

Advantages of using microorganisms to produce food

Answer 25

-making single-celled proteins can be a mechanisms to get rid of waste products–} can be used as organic substrates
-less land required compared to crop growing or livestock
-reproduce fast and produce protein faster than animals/plants
-can be considered healthier as microorganisms have high protein content and little fat
-production not reliant on climate/seasons
-no welfare issues when growing microorganisms
-nutrient requirements i.e oxygen + glucose are cheap

Question 26

Disadvantages of using microorganisms to produce food

Answer 26

-some microorganisms can also produce toxins in conditions are not optimum
-maintaining sterile conditions is expensive and requires lots of effort
-concerns about eating GM foods i.e texture, taste, grown on waste products
-protein has little natural flavour
-if consumed in high quantities, health problems could be caused due to high levels of uric acid when large amounts of AA are broken down

Question 27

Producing penicillin

Answer 27

-fungi(usually P.chrysogenum) from the Penicillium genus produce an antibiotic that stops bacteria from growing + competing for resources
-produced under stress using industrial fermenters:
• relatively small fermenters because
it is very difficult to maintain high levels of oxygenation in very
large bioreactors.
• The mixture is continuously stirred to keep it oxygenated
• There is a rich nutrient medium.
• The growth medium contains a buffer to maintain pH at around 6.5
• The bioreactors are maintained at about 25-27°C
-penicillin is then collected and purified to be used in medicine

Question 28

Producing insulin

Answer 28

-crucial for treating people with type 1 diabetes
-made by genetically modified bacteria, which have had the gene for human insulin production inserted into their DNA
-bacteria are grown in an industrial fermenter on a large scale + the insulin produced is collected and purified

Question 29

Bioremediation

Answer 29

-microorganisms are used to break down pollutants from contaminated sites i.e soil or water
• can be done using natural organisms: pollutant removing bacteria that occur naturally at the site are provided with extra nutrients + enhanced growing conditions to break down and neutralise many contaminants(pollutants broken down into less harmful products)
• GM organisms: developing GM bacteria
which can break down or accumulate contaminants which they
would not naturally encounter i.e mercury in water

Question 30

What are cultures of microorganisms?

Answer 30

-population of one type of microorganism that’s been grown under controlled conditions
-done to have large enough no.s of the microorganisms for them to be seen clearly with the naked eye

Question 31

Why must safety procedures be followed when culturing microorganisms?

Answer 31

-always the risk of a mutation taking place —} making the strain pathogenic
-may be contamination with pathogenic microorganisms from the environment

Question 32

what is needed to culture microorganisms?

Answer 32

-right conditions of temp, oxygen and pH