Transcript Cell, tissue and plant tissue culture

Unit 1
Cell and Molecular
Biology
Section 3
Cell, tissue and plant tissue
culture
Conditions required for bacterial
and fungal growth
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An original stock of cells.
The use of aseptic
techniques when
preparing media and
cultures.
A suitable container for
cell growth.
A growth medium
providing essential
nutrients.
Conditions required for bacterial and
fungal growth (cont’d.)
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Opportunity for gas
exchange – usually
provided by bubbling air
through the culture.
Control of factors such
as pH and temperature.
A method of measuring
cell growth – usually by
monitoring optical
density using a
spectroscope.
Uses of fungal cultures
Fungi such as yeast are
used during : Wine making
 Beer making
 Bread making
 Blue cheeses
 Antibiotics
Uses of bacterial cultures
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Bacteria are used in the
production of yoghurt and
cheese.
Conditions required for mammalian cell
growth
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Mammalian cells are more fragile than
microbial cells so require carefully controlled
conditions.
As well as the requirements given for
microbial cells, mammalian cells also require
a complex growth medium ( containing foetal
bovine serum or FBS) as well as additives
such as pH indicator, antibiotics and animal
serum.
Production of mammalian cells
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Treating tissue with proteolytic enzymes (e.g.
trypsin) to give a primary cell culture from
which others can be obtained.
These cloned cultures only have a limited life
span as mammalian cells only divide a limited
number of times.
Production of mammalian cells (cont’d.)
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Mammalian cells can also be obtained by using
immortalised cell lines (e.g. hybridomas) derived
from tumours.
These cells are neoplastic and will produce tumours
if transplanted.
Mammalian cells require a solid surface for growth
and grow as a monolayer until they cover the
surface of the vessel.
When the surface of the vessel is covered, the cells
are said to be confluent/confivent and growth
stops until a new culture with fresh media is created.
Uses for mammalian cells
Mammalian cells are required for: research into normal cell growth.
 production of new tissue for skin grafts
 replacement of important cells e.g. stem cells are
being trialled to replace cells lost through
Alzheimer's or to help regenerate nerves
 Production of antibodies for use in diagnostics and
to help carry drugs to specific sites
Activity
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Read Dart Pg 20-22
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Scholar (Unit 1, 3.1-3.3)
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Look at techniques in microbial culture and
cloning cells for an interferon Bioassay
Plant Tissue Culture
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Plant tissue culture is used to create clones.
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This is useful
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To create pathogen free species
Create crop species that have identical traits (e.g.
height)
Save endangered species
Somatic Fusion (Protoplast hybridisation) is
used to create new varieties.
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Plant tissue culture is then used to grow the plant
Somatic Fusion
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Cells from two different plants are selected
Cell wall is removed using cellulase and
pectinase
Protoplasts are fused using either
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Polyethylene Glycol
Electrical shock
Protoplast is grown using tissue culture
Plant Tissue Culture
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Source of cell / tissue
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Small pieces of tissue are taken from a plant.
These are called explants.
Protoplast from somatic fusion.
Plant cells / tissue have a long life span
Suitable container
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Anything sterile (the entire procedure must be
carried out under aseptic conditions).
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Growth Medium
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Simple (can be liquid or solid) containing carbon
source, minerals salts, water, vitamins
Contains plant growth regulators to cause tissue
differentiation e.g.
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Cytokinins promote shoot development
Auxins promote root development
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Events in Plant Tissue culture
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Explant is removed and sterilised.
It is transferred to growth media
A mass of undifferentiated cells called the callus forms
(this occurs due to auxin and cytokinin concentrations
being balanced).
Tissue is transferred to growth media containing different
concentrations of growth regulators to promote shoot and
root production.
Tissue culture plants acclimatised in greenhouses.
Totipotency
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Totipotency is the cell’s ability to differentiate.
In theory, all cells have this potential as they
have the same genome (nuclear
totipotency)
In practise,
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Plant cells are totipotent
Mammalian cells vary
e.g. Stem cells are totipotent
Activity
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Read Dart Pg 23-24
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Scholar (Unit 1, 3.4-3.6)
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Create a table to compare the 3 types of
tissue culture.