cloning Flashcards
define clone
genetically identical organism derived from a single parent
where does cloning occur
in nature (MZ twins) and artificially
what is reproductive cloning
produce offspring that is g.identical
what is non-reproductive cloning
use of stem cell to g. replacement cells to treat disease
describe the processes involved in somatic cell nuclear transfer
somatic donor donates its nucleatic DNA
the ovum donor’s cell is denuclieated and the somatic cell’s nucleus is transferred to the denucleated cell
the cell is implanted into a surrogate
how does natural plant cloning occur
in bulbs
leaf bases swell with stored food and buds form
runners
lateral stem grows away from the parent and roots develop wherethe runner touches the ground
rhizomes – specialised horizontal stem underground
stem tubers
tip of underground stem becomes swollen with food to form a tuber
how can we increase plant numbers cheaply
splitting up bulbs
removing young plants from runners
cutting up rhizomes
why is propagation from cutting better
much faster and guaranteed quality of plants
taking cuttings from good stock means the offspring are g. identical so crop well
what is the downside to cuttings
lack of genetic variation
means the crop won’t cope with new diseases or climate change
define micropropagation
process of making large number of g.i. offspring from single parent using tissue culture techniques
when is micropropagation useful
plant doesn’t readily produce seeds
doesn’t respond well to natural cloning
is very rare
has been genetically modified or selectively bred
what is the use of sodium dichloroisocyanurate
make emergency drinking water and babies’ bottle safe
keeps plant sterile in non-sterile conditions
(useful for field work)
describe the principle of propagation
take a small plant sample
sample is sterilised
explant is placed in culture medium
cells proliferate
callus is divided up and individual cells are transferred to new culture medium
plantlets are potted into compost and grow into small plants
production of crop
what are the pros of micropropagation
allows rapid production of desirable plants
produces viable numbers of plants
produces plants without seeds for consumer tastes
grows plants which are relatively infertile or difficult to grow from seed
increases the number of rare plants
what are the cons of micropropagation
produces monoculture (lack of g.variation)
expensive
explants are vulnerable to infection
source material can be infected with virus
large number of new plants are lost
