6.4 CLONING AND BIOTECHNOLOGY Flashcards
What is vegetative propagation?
Vegetative propagation, or natural cloning, occurs in many species of flowering plants. A structure forms which develops into a fully differentiated new plant, which is genetically identical to the parent. The new plant may be propagated from the stem, leaf, bud or root of the parent, depending on the type of plant, and it eventually becomes independent from its parent. It often occurs in perennating organs, which enables plants to survive adverse conditions, and contain stored food from photosynthesis and can remain dormant in the soil.
for example, strawberry and spider plants.
Where does natural plant cloning occur in?
Natural plant cloning occurs in:
bulbs- e.g daffodil. the leaf bases swell with stored food from photosynthesis, buds form internally which develop into new shoots and new plants in the next growing season.
runners- e.g strawberry or spider plant. a lateral stem grows away from the parent plant and roots develop where the runner touches the ground, a new plant develops, runner eventually withers away leaving the new individual independent.
rhizomes- e.g marram grass. a specialised horizontal stem running underground, often swollen with stored food. buds develop and form new vertical shoots which become independent plants.
stem tubers- e.g potato. the tip of an underground stem becomes swollen with stored food to form a tuber or storage organ, buds on the storage organ develop to produce new shoots.
Why is natural cloning used in horiculture.
Natural cloning is exploited in horticulture by farmers and gardeners to produce new plants. It increases plant numbers cheaply, and the new plants have exactly the same genetic characteristics as their parents.
What are the advantages of using vegetative propagation instead of planting seeds?
Propagation from cuttings has many advantages over using seeds. It is much faster and guarantees quality of plants
What are the diadvantages of using vegetative propagation instead of planting seeds?
The main disadvantage for using propagation over seeds is the lack of genetic variation in the offspring should any disease or pest appear or if the climate changes.
Which food crops are produced via propagation?
Many of the worlds most important food crops are propagated by cloning
bananas, sugar cane, sweet potatoes and cassava are all propagated from stem cutting or rhizomes
coffee and tea bushes are also propagated from stem cuttings.
How is sugar cane cloned?
Sugar cane is cloned by cutting short lengths of sugar cane that are about 30cm long, with three nodes, and buried in a clear field in shallow trenches, covered with a thin layer of soil. Per hectare, 10-25000 lengths of stem are planted.
What is micropropagation?
Micropropagation is the process of making large numbers of genetically identical offspring from a single parent plant using tissue culture techniques. This is used to produce plants when a desirable plant does not 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 e.g strawberries, bananas and potatoes
What are the basic principles for micropropagation and tissue culture?
Basic principles for micropropagation and tissue culture:
1. take a small sample of tissue from the plant to be cloned- the meristem tissue from shoot tips and axial buds is often dissected out in sterile conditions to avoid contamination by fungi and bacteria. this tissue is usually virus free
2. the sample is sterilised, usually by immersing it in sterilising agents such as bleach, ethanol, or sodium dichloroisocyanurate. the latter does not need to be rinsed off which means the tissue more likely to remain sterile. the material removed from the plant is called the explant
3. the explant is placed in a sterile culture medium containing a balance of plant hormones (including auxins and cytokinins) which stimulate mitosis. the cells proliferate, forming a mass of identical cells known as 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 tiny, genetically identical 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 advantages of micropropagation?
Advantages of micropropagation:
- allows for the rapid production of large numbers of plants with known genetic make-up 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 therefore sterile to meet consumer tastes (e.g bananas and grapes)
- provides a way of growing plants which are naturally relatively infertile or difficult to grow seed from (e.g orchids)
- provides a way of reliably increasing the numbers of rare or endangered plants
What are the disadvantages of micropropagation?
Disadvantages of micropropagation:
- produces a monoculture (many plants which are genetically identical) so they are all susceptible to the same diseases or changes in growing conditions
- a relatively expensive process and requires skilled workers
- the explants are vulnerable to infection by moulds and other diseases during the production process
- if the source material is infected with a virus, all of the clones will also be
- in some cases, large numbers of new plants are lost during the process
What is animal cloning?
Animal cloning:
- the goal is to take control of the reproductive process
- it is possible to select the specific combination of genes to get what you want which is appealing to people who breed animals
- researchers hope that these technique can be used in researching and treating human diseases and genetically altering animals for the production of human transplant organs
What is artificial twining?
Artificial twining:
- each cell in an early embryo is totipotent
- a split in the early embryo is produced manually
- used by the farming community to produce maximum number of offspring from good dairy/beef cattle or sheep
- process clones an embryo
Artificial twining- cattle casestudy.
Artificial twining- cattle casestudy:
- hormones used to enable to enable a cow with desirable traits to super ovulate
- ova are fertilised by male with desired traits = in vivo/in vitro
- around day 6 the embryo is split into several embryos
- they are then grown in a lab for a few days before being implanted into a surrogate
What is the process of somatic cell transfer?
Somatic cell transfer:
1. nucleus removed from somatic (body) cell of a desirable adult animal
2. nucleus removed from mature ovum of a different female
3. nucleus from adult somatic cell is placed into enucleated ovum and given a mild electric shock so it fuses and begins to divide
4. embryo transferred to surrogate and new embryo will be a clone of the animal from which the somatic cells are derived
What are the pros for animal cloning?
Pros for animal cloning:
- enables high yielding farm animals to produce more high yielding offspring
- enables success of a sire (male) at passing on desirable genes
- if the first cloned embryo is a successful breeding animal, more identical animals can be reared from reaming frozen clones
- many embryos from one engineering procedure
- used in pharming
- clone specific animals = e.g replace pets and top class race horses
- enable rare, endangered or extinct animals to be reproduced
What are the cons for animal cloning?
Cons for animal cloning:
- SCNT is a very inefficient process = takes many eggs to produce one clone
- many cloned animal embryos fail to develop and miscarry or produce deformed offspring
- animals produced by cloning have shortened lifespans
- SCNT relatively unsuccessful in increasing populations of rare organisms or allowing extinct species to be brought back to life
What is biotechnology?
Biotechnology involves applying biological organisms or enzymes to synthesise, breakdown or transformation of materials (in the service of people)
biotech describes a range of methods
- traditional methods (cheese, yoghurt, wine and bread production)
- latest molecular technologies (DNA manipulation to produce genetically engineered microorganisms that synthesise drugs such as insulin)
- use of biological systems to remove soil and water pollution (bioremediation)
