CLONING Flashcards
Cloning
The process of producing genetically identical cells or organisms from the cells of an existing organism
Vegetation propogation
Production of plant clones from non-reproductive tissues (stems, roots, leaves)
Examples of natural vegetative propagation
Rhizomes- stem structures that grow horizontally underground away from parent plant, they have nodes from which new shoots and roots develop
Stolons (runners)- similar to rhizomes but they grow above the ground on the soil surface, new shoots and roots develop from nodes or form at the end of stolons
Suckers- shoots that grow from sucker buds present on the shallow roots of a parent plant
Tubers- large underground structures that grow from sucker buds present on the shallow roots of a parent plant
Bulbs- underground food store, new bulbs are able to develop from the original bulb and form new individual plants
Cuttings
Take a cutting from the parent plant stem
Remove leaves from lower end leaving one at the tip
Dip the lower end of the cutting in rooting powder which contains hormones that induce root formation
Plant cutting in a suitable growth medium
Provide cutting with a moist, warm environment by either using a plastic bag or putting it into a propagation
How to artificially clone a plant
TISSUE CULTURE
Cells are taken from the original plant that is going to be cloned
Cells from stem and root tip are used as they are stem cells
There cells are sterilised to kill any microorganisms (bacteria and fungi compete for nutrients with plant cells which decreases the growth rate)
These cells are placed in a culture medium containing plant nutrients (glucose) and growth hormones (auxins)
When cells have divided and grown into a small plant they are taken out of the medium and are planted in the soil, they will grow into genetically identical plants
When is tissue culture used
To clone plants that don’t readily produce
Clone plants that are endangered or rare
Grow whole plants from genetically engineered plant cells
Micropropagation
Tissue culture is used to produce lots of cloned plants very quickly
Cells are taken from developing cloned plants and subcultured
Repeating this process creates large number of clones
Arguments for artificial plant cloning
Desirable genetic characteristics always passed onto clones
Reproduction takes place in all seasons
Less space required
Provides lots of plants quickly compared to time taken from seeds
Arguments against artificial plant cloning
Undesirable characteristics always passed on
No genetic variability
Single disease could kill them all
Production cost of tissue culture is very high due to high energy use and training of skilled workers
Unsuitable for small scale production
Contamination by microorganisms during tissue culture can be disastrous and can result in the complete loss of plants being cultured
Natural cloning
Once the egg has been fertilised it can split during the early stages of development and develop into multiple embryos with the same genetic information
Embryos can develop as normal to produce offspring that are genetically identical
Methods of artificial animal cloning
Artificial embryo twinning
Somatic cell nuclear transfer (SCNT)
Artificial embryo twinning
An egg is extracted from a female cow and is fertilised in a Petri dish
The fertilised egg is left to divide at least once, forming an embryo in vitro (outside living organism)
The individual cells from the embryo are separated and each is put into a separate Petri dish
Each cell divides and develops naturally forming an embryo
The embryos are then implanted into female cows which act as surrogate mothers
Embryos continue to develop inside the surrogate cows and eventually the offspring are born, all genetically identical
Somatic cell nuclear transfer (SCNT)
A somatic cell is taken from sheep A and the nucleus is extracted and kept
An oocyte (immature egg cell) is taken from sheep B and its nucleus is removed to form an enucleated oocyte
The nucleus from sheep A is inserted into the enucleated oocyte
The nucleus and the enucleated oocyte are fused together and stimulated to divide by an electrofusion where an electrical current is applied
An embryo is produced
The embryo is then implanted into a surrogate mother and eventually a lamb is born that’s a clone of sheep A
Uses of animal cloning
Scientific research
Save endangered animals from extinction
In agriculture so farmers can increase number of individuals with desirable characteristics to breed from
Animals can be genetically modified to produce useful substances
Some scientists only want cloned embryonic stem cells which can be harvested from young embryos and have the potential to become any cell type
Arguments for animal cloning
Desirable characteristics always passed on
Infertile animals can be reproduced
Increasing population of endangered species preserves biodiversity
Animals can be cloned at any time
Cloning can help us develop new treatments for diseases which could mean less suffering for some people
