Chapter 22: Cloning and Biotechnology Flashcards
4 types of natural cloning in plants:
Bulbs, Runners, Rhizomes, Stem Tubers
Natural Cloning: Bulbs
Leaf bases swell with stored food, buds form internally which develop into new plants after leaf abscission.
Natural Cloning: Runners
A lateral stem grows away from the parent plant, the plant develops roots where the stem touches the ground. The runner withers away leaving the individual plant.
Natural Cloning: Rhizomes
A rhizome is a specialised horizontal stem running underground, often swollen with food. Buds develop on the rhizome, forms vertical shoots which becomes independent plants.
Natural Cloning: Stem Tubers
Tip of an underground stem becomes swollen with stored food to form a tuber or storage organ. Buds on the tuber produce new shoots.
Natural Cloning in Horticulture:
Splitting up bulbs, removing young runners, cutting up rhizomes,
Cloning sugar cane:
Fastest growing crop -> Propagated cloning -> cloned using cuttings
When is micropropagation used?
When the desired plant: does not readily produce seeds, doesn't respond well to natural cloning, is very rare, genetically modified or selectively bred with difficulty, Required to be pathogen-free,
Steps of Micropropagation:
- Small tissue sample taken from the meristematic tissue under sterile conditions.
- Sample is sterilised by immersing the tissue in sterilising agents.
- The explant is placed in a sterile culture medium and containing a balance of plant hormones to promote mitosis.
- The cells proliferate forming a mass of cells known as a callus.
- The callus is divided up and individual cells or clumps are transferred to new culture mediums containing nutrients for growth,
- The plantlets are potted into compost
- Young plants are planted out to grow into small plants.
What is the explant:
Sterilised material removed from the plant.
+ves of micropropagation:
- Culturing meristem tissues produces disease-free plants
- Allows for rapid production of plants with the same genetic make-up
- Reliably increases numbers of rare or endangered plants
- Produces large numbers of seedless plants
- Provides a way of reproducing difficult to grow or infertile plants.
- It’s possible to form viable numbers of GMO’s
-ve’s of micropropagation:
- Produces a monoculture susceptible to diseases of changes to conditions
- Expensive process
- Plantlets and explants vulnerable to infection during the production process
- Large numbers of plants can be lost
Natural Animal Cloning:
Animal cloning is most common in invertebrate animals, but can still occur in vertebrates e.g twinning.
Natural Cloning in Invertebrates:
- Some can generate an entire animal from fragments of the original.
- Hydra produce small ‘buds’ on the side of their body which can develop into genetically identical clones.
Natural Cloning in Vertebrates:
- Monozygotic twins (identical twins) -> Early embryo splits
- Female amphibians can produce offspring when no male is available -> not genetically identical but arise from same genetic material.
Artificial Cloning Animals:
Artificial Clones of invertebrates can be formed by extracting fragments.
Two methods for artificial cloning of vertebrates.
Artificial Twinning Animals:
The early embryo is manually split into two or more pieces and the pieces develop into identical offspring.
Steps of artificial twinning:
1) Livestock with desired traits treated with hormones to super ovulate (Stimulates ova release)
2) The ova (oocytes) are fertilised naturally or by artificial insemination by a bull with good traits. Early embryo’s flushed out of the uterus. Another method is the mature egg cells are removed and fertilised by semen in lab
4) Usually before day 6 the cells are still totipotent the cells of the early embryo are split to produce smaller embryos.
5) Each embryo is grown in the lab to ensure no complications before being implanted into surrogate mothers.
6) Embryo’s develop and are born naturally.
What is an enucleated egg cell?
An oocyte which has had its nucleus removed.
What are the two methods of artificial cloning vertebrates (reproductive cloning):
Artificial Twinning and Somatic Cell Nuclear Transfer
What is an oocyte?
An immature egg cell in the ovum.
Benefits of artificial twinning:
Possible to greatly increase the numbers of offspring produced by animals with best genetic stock. Some of the embryos can be frozen and assessed.
During SCNT why are different breeds used for the cell donor, egg donor and surrogate mother?
To ensure that the correct animal has been cloned and to make it easier to identify the original animal at each stage.
Stages of SCNT:
1) The nucleus is removed from the somatic cell of an adult animal.
2) The nucleus is removed from a mature ovum harvested from a different female animal of the same species.
3) The nucleus from the adult somatic cell is inserted into the ovum and given a mild electric shock so it fuses and begins to divide. In some cases the two cells fuse in the presence of an electric current (electrofusion) and begin to divide.
4) The embryo develops and transferred into the uterus of a third animal.
5) The new animal is a clone of the somatic cell donor.
Why is a clone produced by SCNT not a complete genetic match?
- Mitochondrial DNA will come from the egg cell
- Mutations to the Somatic Cell Nucleic Acid.
Uses of SCNT:
Pharming- production of animals genetically engineered to produce therapeutic human (pharmaceutical) proteins.
Produce genetically modified animals to grow human organs for transplants.
Pros of Animal Cloning:
- Artificial Cloning - enables high-yielding farms to produce more offspring - Enables the success of a sire (male) at passing on desirable genes to be determined (cloned parents)
- SCNT - enable GM embryos to be replicated and develop, giving many embryos from one procedure -Enables scientists to clone specific animals - Enable rare, endangered, and extinct animals to be reproduced.
Cons of Animal Cloning:
SCNT - Inefficient process -> most animals require many eggs to produce a single cloned offspring
Many cloned animal embryos fail to develop, miscarry or produce malformed offspring.
Many animals produced by cloning have reduced lifespans.
SCNT is often unsuccessful in increasing the populations of endangered animals.
Biotechnology:
The application of biological organisms or enzymes to the synthesis, breakdown or transformation of materials in the service of people.
Bioremediation:
Microorganisms are used to breakdown pollutants and decontaminate soil or water.
Why are microorganisms used?
- No welfare issues, only need the optimum conditions for growth.
- Variety of microorganisms capable of a variety of reactions
- Genetic engineering allows for artificial manipulation to carry out reactions not seen naturally.
- Have a short life cycle and rapid growth rate -> quantities can be produced in a short amount of time.
- Simple and cheap nutrient requirements.
- Bioprocesses cheaper than non-biological industrial processes.
Indirect food production:
Microorganisms change/alter the food.
Direct food production:
Microorganisms create the food.
Indirect Food Production: Baking: What microorganism(s)?
Yeast -> mixed with water to respire aerobically -> CO2 produced makes bread rise
Indirect Food Production: Brewing: What microorganism(s)?
Yeast -> respires anaerobically to produce ethanol. GM yeast ferments at lower (cheaper) temperatures and flocculates at the end of the process.
Indirect Food Production: Cheese-making: What microorganism(s)?
Bacteria - feed on lactose in milk changing the texture and inhibit the growth of unwanted bacteria.
Indirect Food Production: Yoghurt-making: What microorganism(s)?
Bacteria - (Lactobacillus bulgaricus) forms ethanal. Streptococcus thermophilus (forms lactic acid). Both produce extracellular polymers that give yoghurt its texture.
Indirect Food Production: Baking: Process
- Active yeast added to flour and other ingredients - mixed in warm environment
- Dough is knocked back (remove excess air), kneaded and shaped
- Cooked in hot oven - CO2 bubbles expand the bread and kill yeast cells