A2 OCR Biology: Biotechnology and Gene Technologies

A2 OCR Biology: Biotechnology and Gene Technologies

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  • Created on: 25-05-11 00:09
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Biotechnology and Gene Technologies
Cloning
Reproductive Cloning ­ new individuals with the genotype of the existing individual.
Non-reproductive Cloning ­ cells, not individuals, with the genotype matching the
individual.
Plants
Any form of asexual reproduction involving growth of new parts that can separate
from the parent is known as vegetative reproduction.
When used by humans it's known as vegetative propagation.
Meristem Culture ­ meristems contain unspecialised cells that divide by mitosis. Viruses
tend not to infect the meristems, so they can be removed from plants and used to produce
virus-free material for cloning. Meristems grow into plantlets that have buds with more
meristems that are subdivided to repeat the process.
Callus Culture ­ a callus is a mass of undifferentiated tissue that forms when pieces of
shoot, root or leaf are placed in tissue culture. Callus cells can be maintained in tissue culture
and subdivided to give large quantities of tissue for cloning. If the growth medium contains
appropriate concentrations of plant growth substances (i.e. auxins and cytokinins); roots or
shoots will develop to give genetically identical plantlets.
Suspension Culture ­ Plant cells from callus cultures are separated from one another and
maintained in suspension in a liquid medium.
Advantages of Plant Tissue Culture Disadvantages of Plant Tissue Culture
Uniform plants make harvesting easier; the All are susceptible to the same pathogen or
quality of the crops is the same pest species
Makes clones of plants that cannot
Propagates single clones that may have
reproduce sexually to set seed and can be
genetic diseases / genetic disorders
used to clone transgenic plants
Conditions in tissue culture must be kept
Allows stocks to be built up quickly
sterile to prevent contamination
Propagating plants vegetatively is labour
Tissue culture can be set up anywhere intensive and tissue culture required trained
staff and expensive equipment.

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Animals
Dairy cattle are cloned by using hormones that stimulate the ovaries to produce a large
number of eggs. This is known as superovulation. These eggs are harvested from the ovary
and fertilised in vitro by sperm from a superior bull. The zygotes divide by mitosis and the
resulting embryos are all sexed, subdivided several times and implanted into the surrogate
mother cows. This means that all the resulting calves are clones of each other but not their
mother.…read more

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