Module 6 Section 5: Cloning and Biotechnology Flashcards
What is cloning
Process of producing genetically identical cells or organisms from cells of an existing organism
How can cloning be carried out
Cloning can occur naturally in some plants and animals
Can be carried out artificially instead
What is vegetative propagation
Production of plant clones from non reproductive tissue (not the flower)
Type of asexual reproduction which produces clones
E.g. roots leaves and stems
What are stolons/runners
Similar to rhizomes
Grow above ground on surface of soil
New shoots and roots can develop from nodes or form at the end of the stolon
E.g. strawberries
Rhizomes
Stem structures that grow horizontally underground away from parent plant
Have nodes where new shoots and roots can develop
E.g. bamboo
What are bulbs
Underground food stores
New bulbs can develop from original bulb and form new individual plant
E.g. onions
What are tubers
Large underground food stores
Have eyes which can sprout and from a new plant
E.g. potatoes
What are suckers
Large underground food stores
Have eyes which can sprout and from a new plant
E.g. elm trees
Different types of plant cloning
Natural:
Plant cuttings
Vegetative propagation
Artificial:
Tissue culture
Micro propagation
Techniques of artificial vegetative propagation
Cuttings
Grafting
Layering
All rely of formation of meristematic tissue from which plant organs can differentiate
Creates cultivars
What is taking cuttings
Taking and growing a cutting from a stem/root/leaf
Process of taking cuttings
Cuttings are part of the plant that is cut off of the parent plant.
Shoots with leaves attached are usually used.
New roots and leaves will grow from the cutting.
The shoot is cut at an angle.
A growth promoter may be used to help with the growth of the roots.
What is grafting
Joining the shoot of one plant to the growing stem and root of another plant.
Process of grafting
In grafting 2 plants are used to develop a new plant with combined traits from the 2 parent plants.
In grafting the scion is the above ground part of one plant.
The scion is attached to the stock which is the rooted part of the second plant.
What is layering
Bending the stem of a growing plant downwards so it enters the soil and grows into a new plant.
Process of layering
In layering a shoot of a parent plant is bent until it can be covered by soil.
The tip of the shoot remains above ground.
New roots and eventually a new plant will grow.
These plants can then be separated
Method of producing a clone from a cutting
Use a scalpel or sharp secateurs to take a cutting, between 5 cm and 10 cm long, from the end of a stem of your parent plant between nodes (between 2 leaf joints)
Choose health stem
Cut stem at slant
Remove the leaves from the lower end of your cutting leaving just one at the tip.
Dip lower end of the cutting in rooting powder
This contains hormones that induce root formation.
Plant cutting in a pot containing a suitable growth medium (e.g. well-drained compost).
Provide cutting with a warm and moist environment by either covering the whole pot with a plastic bag or by putting it in a propagator (a specialised piece of kit that provides these conditions)
When your cutting has formed its own roots and is strong enough, plant it elsewhere to continue growing.
Problems of the method to produce a clone from a cutting
Cannot produce many clones at once
Process of growing an artificially cloned plant with tissue culture
Cells are taken from the original plant that’s going to be cloned (can also use explant)
Cells from the stem and root tips are used because they’re stem cells
Plant stem cells are totipotent: can develop into any type of cell
The cells are sterilised to kill any microorganisms (bacteria and fungi that compete for nutrients with the plant cells)
This would decreases their growth rate.
The cells are placed on a culture medium containing plant nutrients (glucose for respiration) and growth hormones (auxins)
When the cells have divided and grown into a small plant they’re taken out of the medium and planted in soil
Then develop into plants that are genetically identical to the original plant.
When is tissue culture used
Used to clone plants that don’t readily reproduce or are endangered or rare
e.g. British orchids.
It’s also used to grow whole plants from genetically engineered plant cells
What is micropropagation and how is it done
When tissue culture is used to produce lots of cloned plants very quickly.
Cells are taken from developing cloned plants and subcultured (grown on another fresh culture medium)
Repeating this process creates large numbers of clones
Where is micropropagation used
Used extensively in horticulture and agriculture
e.g. to produce fields full of a crop that has been genetically engineered to be pest-resistant.
Difference between agriculture and horticulture
Both involve cultivating crops
Agriculture relates to farming
Such as crops for human use
Horticulture involves cultivating any plant for any purpose usually on a smaller scale
Arguments for plant cloning
Desirable genetic characteristics are always passed on to clones
Doesn’t always happen when plants reproduce sexually.
Tissue culture allows plants to be reproduced in any season because the environment is controlled.
Less space is required by tissue culture than would be needed to produce the same number of plants by conventional growing methods.
It produces lots of plants quickly compared to the time it would take to grow them from seeds