6.2.1 Cloning and Biotechnology Flashcards
What are clones?
Genetically identical copies of organisms or cells.
How are clones produced?
Asexual Reproduction - where the nucleus divides by mitosis. No genetic variation although there may be some chemical and psychological changes.
What happens during mitosis?
Creates two identical copies of the DNA
Can clones occour naturally?
Yes - with organisms that reproduce asexually
What are the advantages of natural cloning?
if the conditions are good for the parent then they will be good for the offspring.
Rapid so the population can increase quickly (allows them to take advantage of suitable environmental conditions that may not be around for long).
Reproduction can still take place with only one parent.
What are the disadvantages of natural cloning?
Offspring may become overcrowded.
No genetic diversity (except those caused during mutations).
The population shows little genetic diversity.
Selection is not possible.
The whole population is susceptible to environmental changes.
What is vegetative propagation?
The process of reproduction through vegetative parts of the plant rather than specialised reproductive structures.
What are Runners/Stolens?
stems that grow horizontally from the plant at certain points and grow on the surface of the soil.
What are Rhizomes?
stems that grow horizontally from the plant at certain points and grow under the soil.
What are suckers?
Stems that grow from the root of the plant to form new plants.
What happens once Runners/Stolens, Rhizomes and Suckers have formed?
The horizontal branch dies and leaves the new stem as a separate individual.
What are Bulbs?
An underground stem that grows a series of fleshy leafy bases.
What is the main characteristic of a bulb?
There is an apical bud that grows into the plant in the spring. They typically have more than one apical bud that grows into new plants.
What are corms?
An underground stem with scaly leaves and buds. In the spring they grow into plants.
How do corms differ to bulbs?
Corms are similar to bulbs but are solid rather than fleshy.
How are leaves involved in vegetative propagation?
New leaves can be produced from leaf margins
What are tubers?
Underground stems that grow into a plant. Each tuber produces more later in the year
What is an example of a tuber?
Potatoes
What are examples of natural cloning in animals?
Identical twins.
Asexual reproduction.
How are identical twins produced?
The fertilised egg (zygote) divides as normal but the daughter cells then split to become two separate cells. Each cell grows and develops into a new individual.
What are examples of asexual reproduction in animals?
Water flea and greenfly are able to asexually reproduce to produce clones if needed.
What is the most efficient way to make plant clones?
Cuttings
How are cuttings used to produce clones?
The stem is cut between two nodes (leaf joints). The cut end is placed in moist soil and new roots will grow from the tissue in the stem.
How can root growth be stimulated on cuttings?
By dipping in auxin
Why are cuttings used to produce closes?
You can produce a large number of plants very quickly.
Where can cuttings be obtained from?
Stems, roots, scions and leaves
What are scions?
Dormant woody twigs
What is tissue culture?
Techniques used to grow cells, tissues or organs from a small sample of cells or tissue. Done in a nutrient medium under sterile conditions.
When is tissue culture used?
In commercial situations to increase the number of plants.
What is an example of tissue cloning?
Micropropagation
What is micropropagation?
Taking a small piece of plant tissue (known as the explant) and using plant growth substances to encourage it to grow and develop into new plants.
What is the process of micropropagation?
Plant material is selected and cut into small pieces (explants). Meristems are typically used.
Explants are sterilised using dilute bleach or alcohol.
Explants were placed on a sterile growth medium containing suitable nutrients.
This stimulates division by mitosis to form a callus.
The callus divides to form more clumps of totipotent cells.
The clumps are stimulated into plant tissue.
Plants are transferred to a greenhouse to grow more and acclimatise to normal growing conditions.
Why are meristems typically used as explants?
They are free from viral infection
What is used to sterilise explants?
Dilute bleach or alcohol