Unit 6.4- Cloning and Biotechnology Flashcards
Clones definition:
Genetically identical organisms or cells
Vegetative propagation definition:
Natural plant cloning
Advantages of natural cloning:
- If the conditions of growth were good for the parent, they will be good for the offspring
- Rapid, the population can rise quickly to take advantage of suitable conditions
- Reproduction can be carried out even if there is only one parent and sexual reproduction is not possible
Disadvantages of natural cloning:
- Offspring may become overcrowded
- No genetic diversity apart from that caused by mutations
- Population shows little variation
- Selection is not possible
- If the environment is less advantageous, the whole population is susceptable
Runners or stolens:
- Horizontal stems from plants
- Can form roots at certain points
- Grow on the surface of the ground
Rhizomes:
- Horizontal stems from plants
- Can form roots at certain points
- Grow underground
- Some can be adapted into thicker overwintering organs from which one or more new stems will grow in the spring
Suckers:
- New stems that grow from the roots of a plant
- The horizontal branch may die, leaving the new stem as a separate individual
Bulbs:
- Overwintering
- Consist of an underground stem from which grow a series of fleshy bases
- There is an apical bud which will grow into a new plant in the spring
- There may be more than one apical bud, these each grow into separate new plants
Corms:
- Solid rather than fleshy
- Underground stem with scaly leaves and buds
- Remain in the ground over winter
- In the spring, the buds grow to produce one or more new plants
Leaves:
- Clones grow on the leaf margins
- The immature plants drop off the leaf and take root
Tubers:
Type of underground stem
Micropropagation definition:
Growing large numbers of new plants from a meristem tissue taken from a sample plant
Tissue culture definition:
Growing new tissues, organs or plants from certain tissues, organs or plants from certain tissues cut from a sample plant
How to clone plants by cuttings:
- Stem is cut between two nodes
- Cut ends placed in moist soil
- New roots will grow
- Some plants will need to be dipped in rooting hormone to help stimulate root growth
How to clone plants by micropropagation:
- Plant material cut into small pieces (explants)
- Explants are sterilised using dilute bleach or alcohol
- Explants placed on agar, containing nutrients and hormones such as auxin
- This stimulates the cells to divide by mitosis and for callus (mass of totipotent cells)
- Once a callus is formed, it is divided to form a large number of small clumps of undifferentiated cells
- Once plantlets have formed, these are transformed to a greenhouse to be grown in compost or soil and are acclimatised to normal growth conditions
Advantages of artificial cloning:
- Rapid
- Can be carried out when sexual reproduction is not possible
- Genetically identical to parent plant so posses same beneficial characteristics
- Uniform phenotype making them easier to grow and harvest
- Using the apical bud ensures plants are free from viruses
Disadvantages of artificial cloning:
- Tissue culture is labour intensive
- Expensive
- Can fail due to micro-bacterial contamination
- Cloned offspring are susceptible to the same pests and diseases. There can be a rapid spread of pests and diseases
- No genetic variation apart from that caused by mutations
Embryo twinning definition:
Splitting an embryo to create two genetically identical embryos
Enucleation definition:
Removal of the cell nucleus
Somatic cell nuclear transfer (SCNT) definition:
A technique that involves transferring the nucleus from a somatic cell to an egg cell
How does embryo splitting work?
- A zygote is created by IVF
- Zygote is allowed to divide by mitosis to form a small ball of cells
- The cells are separated and allowed to continue dividing
- Each small mass of cells is placed int the uterus of a surrogate mother
How does somatic cell nuclear transfer (SCNT) work?
- Enucleation of egg cell
- Somatic cell removed from animal to be cloned. Nucleus is removed
- Somatic cell nucleus fused with empty egg cell by applying electric shock
- Shock triggers egg cell to start developing as though it had just been fertilised
- Cell undergoes mitosis to produce small ball of cells
- Embryo placed in the uterus of a surrogate mother
What can therapeautic cloning be used for?
- Skin grafts
- Repair damage to spinal chord
- Restore capability to produce insulin in the pancreas
- Potential to grow whole new organs to replace diseased organs
Arguments for artificial cloning in animals:
- Can produce whole heard of animals with desirable characteristics
- Using genetically identical embryos for scientific research allows the effects of genes and hormones to be assessed with no interference from different genotypes
- Testing drugs on cloned cells and tissues avoids using people or animals for testing
- Can produce cells genetically identical to the donor, for use in repairing damage
- Individuals from endangered species can be cloned to increase numbers
Arguments against artificial cloning in animals:
- Lack of genetic variation can expose heard to diseases or pests
- Animals may be produced with little regard for their welfare
- Success rate of adult cell cloning is very low
- Expensive
- Ethical issues surrounding how long the embryo survives
- Cloning animals of endangered species may increase numbers, but doesn’t increase biodiversity
Biotechnology definition:
The use of living organisms or parts of living organisms in industrial processes.
Examples of food biotechnology is used in:
- Ethanol in beer and wine (yeast)
- CO2 used to make bread rise (yeast)
- Lactic acid used to make yogurt and cheese (bacteria)
- Mycoprotein (fungus)
- Soya beans are fermented to make soy sauce (yeast)
Examples of pharmaceutical drugs biotechnology is used in:
- Penicillin (fungus)
- Insulin (genetically modified bacteria)