M6, C22 Cloning and Biotechnology Flashcards
where can new plants propagate from
stem
leaf
buds
root
Where does natural plant cloning / vegetative propogation occur?
Bulbs - leaf bases swell with stored food from photosynthesis. Buds form internally which develop into new shoots.
Runners - a lateral stem grows away from the parent plant and roots develop where the runners hit the ground.
Rhizomes - a specialised horizontal stem running underground, often swollen with stored food. Buds develop and form new vertical shoots which become independent plants.
Stem tubers - the tip of an underground stem becomes swollen with stored food to form a tuber or storage organ. Buds develop to produce new shoots.
What are the advantages and disadvantages of using cuttings
faster than using seeds
guarantees quality of the plant
offspring are genetically identical
lack of genetic variation - disease or climate change could wipe them all out
How do you produce a clone from a cutting
1) Use a scalpel to cut a piece of stem from the parent plants between 5 and 10 cm.
2) Remove the leaves from the lower end of your cutting, leaving one at the tip.
3) Dip the lower end of the cutting in rooting powder, which contains hormones that induce root formation.
4) Then plants your cutting in a pot containing well-drained compost.
5) Provide your cutting with a warm and moist environment by covering in a plastic bag or putting in propagator.
6) When your cutting has formed its own roots and is strong enough, plant it elsewhere to continue growing.
define micropropagation
the process of making large numbers of genetically identical offspring from a single parent plant using tissue cultures techniques
when is micropropagation used
When the desirable plant…
- doesn’t readily produce seeds
- doesn’t respond well to natural cloning
- is very rare
- has been genetically modified or selectively bred with difficulty
- is required to be ‘pathogen-free’ by growers
what is the process of micropropagation using tissue culture
1) Take a small sample of tissue from the plant you want to clone. (The meristem tissue from shoot tips and axial buds is often dissected out in sterile conditions to avoid contamination by fungi and bacteria. Usually virus free).
2) Sterilise the sample by immersing in sterilising agents. The latter isn’t rinsed off. The material removed is called the explant.
3) The explant is placed in a sterile culture medium containing a balance of plant hormones (auxins and cytokinins) which stimulate mitosis. The cells multiply, forming a mass of identical cells called a callus.
4) The callus is divided up and individual cells or clumps from the callus are transferred to a new culture medium containing a different mixture of hormones and nutrients which stimulates the development of plantlets.
5) The plantlets are potted into compost where they grow into small plants.
6) The young plants are planted out to grow and produce a crop.
What are the reasons for micropropagation?
- Allows for the rapid production of large numbers of plants which will yield good crops.
- Culturing meristem tissue produces disease-free plants.
- Makes it possible to produce viable numbers of plants after genetic modification of plant cells.
- Provides a way of producing very large numbers of new plants which are seedless and meets consumer tastes.
- Provides a way of growing plants which are naturally relatively infertile or difficult to grow from seed.
- Provides a way of reliably increasing the numbers of rare or endangered plants.
what are the reasons against micropropagation?
- produces a monoculture (many plants that are genetically identical) so all are susceptible to the same diseases or changes in growing conditions.
- relatively expensive process and requires skilled workers.
- the explants and plantlets are vulnerable to infection
- if the source material is infected with a virus, all clones will also be infected.
- in some cases, large numbers of new plants are lost during the process
what is the step-by-step process of artificial embryo twinning (using cows as an example)
1) An egg cell is extracted from a female cow and fertilised in a Petri dish.
2) The fertilised egg is left to divide at least one, forming an embryo (outside a living organism).
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 re then implanted into female cows, which act as surrogate mothers.
5) The embryos continue to develop inside the surrogate cows and eventually offspring are born, all genetically identical to each other.
Give the step-by-step process of somatic cell nuclear transfer (SCNT) (using sheep as an example)
1) A somatic cell is taken from sheep A. The nucleus is extracted and kept.
2) An egg cell (oocyte) is taken from sheep B. Its nucleus is removed to form an enucleated oocyte.
3) The nucleus from sheep A is inserted into the enucleated oocyte so the oocyte from sheep B now contains the genetic information from sheep A.
4) The nucleus and the enucleated oocyte are fused together and stimulated to divide (electrofusion - applying an electric current). This produces an embryo.
5) The embryo is then implanted into a surrogate mother and eventually a lamb is born that’s a clone of sheep A.
what is therapeutic cloning
cloning our own body cells in order to produce new organs
this is beneficial because the body won’t reject the organs (in transplants for example)
Give some different ways vegetative propagation is used in horticulture
1) Cuttings
2) Grafting - joining the shoot of one plant to the stem and root of another
3) Layering - bending a stem of a growing plant downwards so it enters the soil an grows a new plant
4) Split up bulbs
5) Remove young plants from runners
6) Cut up rhizomes (horizontal roots grown underground which produce own shoots)
What are the arguments for animal cloning
- Desirable genetic characteristics are always passed onto clones (eg. high yield)
- Infertile animals can be reproduced
- Animals can be cloned at any time - don’t have to wait till breeding season
- Increasing the population of endangered species helps to preserve biodiversity
- Cloning can help us develop new treatments for disease, which could mean less suffering for some people
What are the arguments against animal cloning
- Animal cloning is very difficult, time-consuming and expensive.
- There’s no genetic variability in cloned populations so undesirable genetic characteristics are always passed on to clones. This means all clones are susceptible to the same diseases so they could all wipe out.
- Evidence suggests clones don’t live as long as natural offspring. Some think this is unethical.
- Using cloned human embryos as a source of stem cells s controversial. The embryos are usually destroyed after the embryonic stem cells have been harvested - could be considered as destroying a human life.
define biotechnology
industrial use of living organisms to produce food, drugs and other products
Why are microorganisms used in biotechnology
- ideal growth conditions easily created
- grow rapidly due to short life cycle so products made quickly
- grown on a range of inexpensive materials
- grown anytime of year
- no welfare issues to consider
- large range of microorganisms capable of different chemical synthesis or degradation
- can artificially manipulate them eg. genetic engineering
How is lactase used in biotechnology
Breaks down lactose
Made from Asperigillus fungi
Used to produce lactose-free products
What are intracellular enzymes
enzymes are contained within cells of a microorganism
what are isolated enzymes
enzymes that aren’t contained in cells
- extracellular enzymes which are secreted naturally by the microorganism
- some have to extracted from cells artificially
what are the indirect ways microorganisms are used in biotechnology
the actions of the microorganisms are what’s important
eg. bread - yeast makes it rise, yoghurt, cheese, beer
needs ideal conditions
needs to be sterile
the microorganisms used have been genetically engineered
ethical issues
what are the direct ways microorganisms are used in biotechnology
Using microorganisms to make proteins we can eat
single-cell protein
eg. Quorn - made of fungus Fusarium venetatum
what microorganism is used in baking and how does it work
Yeast (fungi)
The carbon dioxide produced by fermentation of sugars in the dough makes sure it doesn’t stay flat
what microorganism is used in brewing and how does it work
Yeast (fungi)
Added to barley (type of grain). The yeast respires anaerobically using the glucose from the grain and produces ethanol and carbon dioxide. (Fermentation)
what microorganism is used in making cheese and how does it work
Substance called rennet which contains the enzyme chymosin. This clots milk. It’s extracted from yeast cells that have been genetically modified.
Also, lactic acid bacteria (Lactobacillus or Streptococcus) which converts lactose in milk into lactic acid which contributes to solidifying.
what microorganism is used in making yoghurt and how does it work
Lactic acid bacteria
Clots milk and causes it to thicken.
Makes it sour - flavours are added afterwards.
What are the advantages of using microorganisms in food production?
- Microorganisms used to make single-cell protein can be grown using many different organic substrates, including waste materials.
- They can be grown quickly, easily and cheaply. Only require simple growth requirements and can be grown on waste products and less land is required in comparison to growing crops or rearing livestock.
- Can be cultured anywhere if you have the right equipment so can be used in LEDCs
- Single-cell protein is also often considered a healthier alternative to animal protein
What are the disadvantages of using microorganisms in food production?
- Other microorganisms can grow in the conditions so it takes a lot of effort into making sure food doesn’t get contaminated with unwanted bacteria
- People may not like the idea of eating food that has been grown using waste products
- Single-cell protein doesn’t have the same texture/flavour as real meat
- If single-cell protein is consumed in high quantities, health problems could be caused due to high levels of uric acid released when the large amounts of amino acids are broken down.
what are the aims of fermentation vessels
obtain lots of microorganisms or to collect lots of useful product the microorganism makes