Cloning 6.2.1 Flashcards
5 examples of natural cloning in plants
Rhizomes
- grow horizontally underground away from parent
eg. bamboo
Stolons/Runners
- grow horizontally above ground away from parent plant
eg. strawberries
Tubers
Bulbs
production of natural clones of plants for use in horticulture (vegetative propagation)
- take cuttings
- grafting (joining the shoot of one plant to the growing stem and root of another plant)
- layering (bending the stem of a growing plant downwards so it enters the soil and grows a new plant
what is vegetative production?
production of plant clones from non-reproductive tissues eg. roots, leaves, stems
what’s the difference between a stolon and a rhizome?
a stolon (runner) grows ABOVE ground horizontally and a rhizome grows BELOW ground horizontally
in both, new shoots can develop from nodes along the length or from the end of the stolon/rhizome
how to produce a clone from a cutting
simple cloning technique
- take a cutting of parent plant
- dip the end of the cutting in rooting powder, which contains hormones that induce root formation
- plant cutting in pot containing suitable growth medium
- warm & moist environ. (propagator)
- replant it when roots form
how to artificially clone plants using tissue culture
detail of either medium; e.g. named nutrient or plant growth substance grows to plantlet; hardening medium/sterile soil;
- take cutting from meristematic tissue (stem & roots)
- sterilise to kill microorganisms
- cells grown on nutrient medium to encourage division/mitosis (auxins, cytokines)
- cells divide and form calluses
- subdivided
- put in different (nutrient) medium to encourage differentiation
- when plantlets form, they are planted in soil
- form genetically identical indiduals
what kind of plants is tissue culture used for?
- rare or endangered
- don’t readily reproduce
- can be used to produce whole plants from genetically engineered plant cells
what is micropropagation?
when tissue culture is used to produce lots of cloned plants v quickly
arguments for use of artificial plant cloning
- desirable characteristics always passed on to clones
- any season
- less space
- quicker (than seeds)
artificial plant cloning =
simple cloning from cutting
tissue culture
micropropagation
arguments against use of artificial plant cloning
- undesirable characteristics always passed on to clones
- no genetic variation in pop. so vulnerable to same diseases
- high cost (energy & skilled workers)
- contamination by microorganisms can result in loss of all cultured plants
arguments against use of artificial plant cloning
- undesirable characteristics always passed on to clones
- no genetic variation in pop. so vulnerable to same diseases
- high cost (energy & skilled workers)
- contamination by microorganisms can result in loss of all cultured plants
example of natural clones in animals
monozygotic twins formed by embryo splitting
how artificial clones in animals can be produced by artificial embryo twinning
- female superovulated and treated with hormone
- oviduct/ovary is washed out
- egg cell extracted from female and fertilised in petri dish
- fertilised egg left to divide at least once, forming in vitro embryo
- cells separated and each put in separate petri, dividing and developing to form an embryo
- treat the surrogate mother with hormones before the embryo is implanted so that uterus lining thickens and phase of cycle is synchronised
how artificial clones in animals can be produced by enucleation and somatic cell nuclear transfer (SCNT)
- nucleus extracted from somatic cell of sheep A
- egg cell (oocyte) taken from sheep B enucleated
- nucleus from sheep A inserted into the oocyte from B
- electric shock stimulates them to fuse together and divide
- embryo implanted into surrogate mother