Transcript Plant Cell Culture

Biotechnology – Biotechnological techniques
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Use of micro-organisms
Industrial production of enzymes
Tissue cultures
Cell culture is the cultivation of animal and
plant cells in the laboratory
Cell cultures are used routinely to
produce materials e.g. vaccines and
hormones,
to test the safety of medicines
to study the properties of cells in
isolation e.g. insulin production in the
pancreas
Animal Cell Culture
 It is possible to grow cells from
different organs e.g. pancreas
 Stem cells have also been cultured
and are used to grow human cartilage
and also brain cells (specialised from
stem cells)
Pancreas cells in tissue
culture
(usually animal cells have
to be grown attached to a
surface e.g. plastic. They
are said to be anchorage
dependant. The exception
to this are body fluid cells
e.g. blood cells)
Limitations
 Animal cells are fragile and sensitive
to damage.
 A lack of a cell wall makes them
vulnerable to changes in osmotic
concentrations within growth media.
 Too costly to carry out on a large
scale.
Procedure
 Cells are grown in plastic flasks or dishes.
 Air is carefully bubbled into the vessels (no
shaking as this would damage cells)
 1st batch of cells (primary cell line) are
removed from the stock mechanically and
with the help of enzymes e.g. proteases
 Cell lines grown for many generations
Conditions
 Similar to those for microbes
 Aseptic technique is essential. Often
carried out in an aseptic tissue culture
cabinet.
 Growth media – cocktails of nutrients
are needed.
 Antibiotics are added to prevent the
growth of bacterial contaminants.
Plant Cell Culture
 It is easier to grow plant cell cultures than to
collect plants from the environment.
Cell cultures are used to:
 Study the biological and physical properties of
plant cells isolation.
 Grow cells in a fermenter to collect
metabolites for making drugs, dyes,
fragrances and pharmaceuticals.
 Develop improved crop plants.
Conditions
The following need to be considered.
 Temperature
 Nutrient supply
 Light intensity
 Aseptic technique is essential. Often
carried out in an aseptic tissue
culture cabinet.
Growth of Explants
 An explant is any portion of a plant that is
used to make a culture e.g. leaf disc
 These are then grown on petri dishes with
the appropriate nutrients.
 Calluses (mass of plant cells) form from the
explants
 Calluses are transferred into flasks or
dishes containing the appropriate media
and are grown up into adult plants.
 Plant cells can also be grown in suspension
in fermenters.
 An explant is taken and then it must be
treated with pectinases to separate the
plant cells from each other.
 They are then transferred into fermenters
and can be subcultured from the fermenter.
 For example, Lithospermum plants are used
to produce the antibacterial and antiinflammatory drug: shikonin.
Protoplasts
Protoplasts are used to:
 make monocultures of plants i.e.
genetically uniform plants (clones). This is
useful for crop plants as the uniformity
means that they will all grow/flower/fruit at
the same rate.
 Make genetically pure plant cell tissue lines.
 Engineer genetic hybrids that would be
sexually incompatible in nature.
 Plant tissue or cells from a callus can
be used.
 Their plant cell walls are removed by
enzymes e.g. pectinases and
cellulases.
 Plants are then regenerated from the
plant cell protoplasts.
Hybridisation
 Protoplasts can be used for
hybridisation/protoplast fusion
techniques. These fuse the nuclei of 2
genetically separate species.
 This can overcome sexual
incompatibility between plant species
 Introduce genes for herbicide and
pest resistance
The Technique (aseptic)
Protoplast of species 1
e.g. potato plant
Treated with cellulose and pectinase
to remove cell wall
Protoplast of species 2
e.g. disease resistant plant
Treated with cellulose and pectinase
to remove cell wall
Mix with polyethylene glycol (dehydrates protoplasts)
Protoplasts fuse
Protoplast develops into a callus (treated with auxin and cytokinin for root and shoot growth)
Hybrid plant displays the characterisitics of both parents
disease resistant, edible potato plant
Contains genetic information from both protoplasts (parents)
e.g. disease resistant, edible potato plant
• 2 different Brassica species
• Hybrid plant the result of protoplast fusion
Past Paper Questions
• 2005 Q2 b
• 2006 Q3
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