P2 Cloning Organisms and Biotechnology Flashcards
How do plants clone themselves naturally?
- By vegetative propagation: they reproduce naturally, without fertilisation, producing an offspring that is identical.
- They do this using meristem (found in roots, shoots and between xylem and phloem).
- A miniature plant (plantlet) is able to grow from these areas, once it grows enough to survive on it’s own, the plantlet detaches.
What are the methods of natural cloning in plants?
- Produce clones using horizontal stems, called runners (connecting the parent plant and plantlet).
- Produce clones using tubers (swollen, underground bits of stem). Buds form on the surface of tubers, which develop into clones (plantlets).
- Produce clones using bulbs (underground stems, enclosed by layers of leaves). Buds form between these layers in the bulb, which then develop into clones (plantlets).
- Produce clones using rhizomes (an underground, horizontal stem), which attaches the parent plant to the plantlet.
How can farmers encourage plants to naturally clone?
Using cutting:
1. Cut off bits of a healthy plants stem.
2. Dip the cut stem into growth hormones (eg. auxins).
3. Place the cutting in soil, and cover it with a plastic bag to create a moist, warm environment.
What are the advantages and disadvantages of using cuttings to grow plants?
Advantages:
1. No expensive
equipment
2. Doesn’t require much skill
3. Quicker than growing plants from seeds
Disadvantages:
1. All clones are identical, so they can all be killed off by a single disease, or change in the environment.
2. Only a limited number of clones can be produced from one plant.
3. Some plants don’t respond well to natural cloning.
How are plants artificially cloned?
Micropropagation:
1. Cut off a small sample of meristem tissue (containing totipotent cells) - this sample is called an explant.
2. Sterilise the sample to reduce the chances of contamination.
3. Place the sample in a sterile liquid containing growth hormones, which stimulate the cells to undergo mitosis. This creates a mass of cells called a callus.
4. The callus is then divided, and each part is placed into a new liquid containing hormones and nutrients.
5. These cells form plantlets, which are then potted.
Advantages and disadvantages of artificially cloning plants (micropropagation):
Advantages:
1. Rapidly produces a large number of clones.
2. Used to grow plants that are difficult to grow from seeds.
3. Plants can be grown at any times of the year.
Disadvantages:
1. All of the clones could be killed by a single disease/change in the environment.
2. Expensive process.
3. Requires skill to carry out.
How does cloning occur naturally in animals?
Identical twins:
- after fertilisation the embryo splits, forming twins
How can twins be created artificially?
Artificial embryo twinning:
1. Extract an egg cell from a female animal, and fertilise it in the lab.
2. As the embryo develops, it is split into single cells.
3. These single cells form new identical embryos, which are placed into different surrogate animals.
3. These surrogates give birth to genetically identical offspring.
How can adult animals be artificially cloned?
Using somatic cell nuclear transfer:
1. Extract a somatic body cell, then extract it’s nucleus.
2. From a different animal from that species, extract an unfertilised egg, and extract the nucleus from this egg (enucleation).
3. Insert the somatic cell nucleus into the enucleated egg, and apply an electric shock, which fuses the nucleus into the egg (electrofusion).
4. The transformed egg divides, and forms an embryo.
5. The embryo is transferred into the uterus of the surrogate animal, who gives birth.
Advantages and disadvantages of artificial cloning in animals (somatic cell nuclear transfer)
Advantages:
1. Can be used to clone animals with desirable characteristics eg. high milk yield.
2. Can be used to clone genetically modified animals that produce useful proteins for human medicine.
3. We can harvest stem cells from embryos grown in this way. Stem cells can then grow tissues and organs, which can be used for medical treatment.
Disadvantages:
1. Many cloned animals fail to develop.
2. Cloned animals often die early and have genetic abnormalities.
3. There are ethical issues with harvesting stem cells from embryos, as this destroys the embryo, which could have grown into an organism.
What is biotechnology?
The use of living organisms, such as microorganisms, to make products for humans.
What are the uses of microorganisms in biotechnological processes?
- Make food:
- Bacteria is used to produce cheese and yogurt.
- Yeast is used to make bread and ethanol. - Make medicine, such as penicillin and insulin.
- Bioremediation: microorganisms break down contaminants in land and water, such as oils or pesticides.
Advantages and disadvantages of using microorganisms to make food
Advantages:
1. Microorganisms reproduce very quickly, so large numbers can be grown in a short amount of time.
2. Microorganisms can be grown on waste materials, reducing costs.
3. Microorganisms can produce healthier, high protein, low cholesterol products such as mycoprotein (a meat substitute).
4. Microorganisms can grow in low temperature environments, reducing costs.
Disadvantages:
1. Any contamination in the batch of microorganisms can cause food to spoil, resulting in health risks.
2. People may not want to eat food made using waste products.
3. Food produced has little flavour, so we need to add chemicals.
What is culturing, and what requirements does it need?
The process of growing microorganisms:
1. Nutrients (to provide the microorganisms with everything they need to grow and reproduce). This is provided from a liquid called a broth, or from a jelly-like substance called agar. This is called the nutrient medium.
2. Oxygen for aerobic respiration.
3. Optimum temperatures, to increase rate of enzyme-controlled reactions, without enzymes denaturing.
4. Optimum pH, to increase rate of enzyme-controlled reactions. Changes in pH cause the hydrogen and ionic bonds in enzymes to break.
What are the aseptic techniques used when culturing microorganisms?
- Wear gloves, to prevent microorganisms from our hands being transferred to the samples.
- Keep the agar covered as much as possible to prevent microorganisms from the air contamination the agar. Keep the plate sealed while the microorganisms are growing, and only open the plate for the minimum amount of time, holding the lid over the plate.
- Use fire to kill contaminating organisms, equipment is run through a flame before use, preventing microorganisms from the equipment entering the agar. And flame the mouth of the bottle once the sample is collected, killing any microorganisms that entered the bottle while the lid was off.
