Cloning and biotechnology Flashcards
What is cloning
The process of producing genetically identical cells or organisms from the cells of an existing organism. It can occur naturally in some plants and animals, but it can also be carried out artificially
What is vegative propagation
The production of plant clones from non-reproductive tissues such as roots, leaves and stems
What are the natural vegative propagation methods plants use (8)
Rhizomes
Stolons (runners)
Tubers
Bulbs
Cuttings
Grafting
Layering
What are rhizomes and an example
Stem structures that grow horizontally underground away from the parent plant. They have ‘nodes’ from which new shoots and roots can develop.
E.g Bamboo
What are Stolons (runners) and an example
Quite similar to rhizomes but can grow above the ground on the surface the soil. New shoots and roots can either develop from nodes or form at the end of the stolon
E.g Strawberries
What are suckers and an example
Are shoots that grow from sucker buds present on the shallow roots of parent plant
E.g Elm trees
What are tubers and an example
Large underground plant structures that act as a food store for the plant. They’re covered in ‘eyes’. Each eye is able to sprout and form a new plant
E.g potatoes
What are bulbs and an example
Underground food stores used by some plants. New bulbs are able to develop from the original bulb and form new individual plants.
What is grafting
Joining the shoot of one plant to the growing stem and root of another plant
What is layering
Bending a stem of a growing plant downwards so it enters the soil and grows into a new plant
How do you produce a clone from a cutting
1) Use a scalpel or sharp secateurs to take a cutting between 5 and 10 cm long from the end of a stem of your parent plant
2) Remove the leaves from the lower end of your cutting leaving just one at the tip
3) Dip the lower end of the cutting in rooting powder, which contains hormones inducing root formation
4) Plant your cutting in a pot containing a suitable growth medium
5) Provide the cutting with a warm and moist environment by either covering the whole pot or putting it in a propagator
6) When the cutting has formed its own roots it can be planted elsewhere
What are the two types of plant cuttings and how do they work
Root cutting - cut a piece of root from the plant with a straight cut using a scalpal removing the uncut end of the root with a slanted cut. Dip the end in rooting powder and plant it in a growth medium
Split vein cutting - removing a complete leaf and scoring the large veins on the lower leaf surface using a scalpal. Put it on top of a growth medium with the broken veins facing down. A new plant should form from each break in the veins
How can plants be artificially cloned using tissue culture/micropropagation
1) Cells are taken from the original plant that’s going to be cloned
2) Cells from the stem and root tips are sued because they’re stem cells - like in humans, plant stem cells can develop into any type of cell
3) The cells are sterilised to kill any microorganisms such as bacteria and fungi that compete for nutrients with the plant cells
4) The cells are placed on a growth medium contains plant nutrients such as glucose and growth hormones such as auxins
5) When the cells have divided and grown into a small plant they’re taken out of the medium and planted in soil to develop into plants
What is the difference between tissue culture and micropropagation
Tissue culture is used to clone plants that don’t readily reproduce, are endangered or rare or grow whole plants from genetically engineered plant cells
Micropropagation is when tissue culture is used to produce lots of cloned plants very quickly
What are the arguments for artificial plant cloning
- Desirable genetic characteristics are always passed on to clones. This doesn’t always happen when plants reproduce sexually
- Tissue culture allows plants to be reproduced in any season
- 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
What are the arguments against artificial plant cloning
- Undesirable genetic characteristics are passed on to clones
- Cloned plant populations have no genetic variability so a single disease could kill them all
- Production costs of tissue culture are very high due to high energy use and the training of skilled workers so it’s unsuitable for small scale production
- Contamination by microorganism during tissue culture can be disastrous and result in complete loss of the plants being cultured
How can animal clones occur naturally
During sexual reproduction once an egg has been fertilized it can be split during development into multiple embryos, known as twins
What are the two methods of producing animals by artificial cloning
- Artificial embryo twinning
- Somatic Cell Nuclear Transfer (SCNT)
Process of artificial embryo twinning
1) An egg cell is extracted from a female cow and fertilized in a Petri dish
2) The fertilised egg is left to divide at least once forming an embryo
3) The individual cells from the embryo are separated and each is put into a separate Petri dish. Each cell divides and develops normally, so an embryo forms in each Petri dish
4) The embryos are then implanted into female cows, which act as surrogate mothers
5) The embryos continue to develop inside the surrogate cows, and eventually the offspring are born. They’re all genetically identical to each other
Process of somatic cell nuclear transfer
1) A somatic cell is taken from sheep A and the nucleus is extracted and kept
2) An oocyte is taken from sheep B, it’s nucleus is removed to form an enucleated oocyte
3) The nucleus from sheep A is inserted into the enucleated oocyte from sheep B
4) The nucleus and the enucleated oocyte are fused together and stimulated to divide by electrofusion
5) This produces an embryo which is implanted into a surrogate mother and then a lamb is then born as a clone of sheep A
What is a somatic cell
Any cell that isn’t a reproductive cell
What is an oocyte
Immature egg cell
What are the uses of animal cloning (5)
- Research purposes
- Save endangered animals
- Agriculture
- Producing useful substances
- Make Embryonic stem cells
How can research purposes be a use of animal cloning
Can be used to test new drugs on cloned animals as they are genetically identical