Biotechnology and Gene Technologies
Unit 2
- Created by: Holly-AnneWard
- Created on: 14-01-15 16:08
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- Biotechnology and Gene Technologies
- Artificial Clones and Agriculture
- USED FOR YEARS Artificial vegetative propagation - two main methods:
- Taking cuttings
- Section of stem cut between leaf joints (nodes)
- Cut end of stem often treated with plant hormones to encourage root growth and planted
- Cuttings form new plant which is clone of original parent plant
- Cut end of stem often treated with plant hormones to encourage root growth and planted
- Section of stem cut between leaf joints (nodes)
- Grafting
- Shoot section of woody plant joined to an already growing root and stem (a rootstock)
- Graft grows and is genetically identical to parent plant, but rootstock is genetically different
- Shoot section of woody plant joined to an already growing root and stem (a rootstock)
- Cuttings and grafts cannot produce huge numbers of cloned plants very easily
- Plants do not reproduce well from either cuttings or grafts
- Taking cuttings
- MODERN Artificial propagation using tissue culture: large-scale cloning
- Tissue culture
- Generate huge numbers of genetically identical plants from very small amount of plant material
- Can be used to generate large stocks of a particularly vulnerable plant very quickly, with added advantage that these stocks known to be disease-free
- Micropropagation by callus tissue culture
- Most common method used in the large-scale cloning of plants
- Small piece of tissue taken from plant to be clones, (usually from shoot tip) = an explant
- Explant placed on a nutrient growth medium
- Cells in tissue divide but do not differentiate. Instead form mass of undifferentiated cells = a callus
- After few weeks, single callus cells removed and placed on growing medium containing plant hormones that encourage shoot growth
- Further weeks, growing shoots transferred onto different growing medium containing different hormone concentrations that encourage root growth
- Growing plants transferred to greenhouse to be acclimatised + grown further before planted outside
- Further weeks, growing shoots transferred onto different growing medium containing different hormone concentrations that encourage root growth
- After few weeks, single callus cells removed and placed on growing medium containing plant hormones that encourage shoot growth
- Cells in tissue divide but do not differentiate. Instead form mass of undifferentiated cells = a callus
- Explant placed on a nutrient growth medium
- Tissue culture
- Advantages of plant cloning in agriculture
- Propagation using callus culture means:
- Farmers know what the crop plant produced will be like because it it cloned from plants with known features
- Farmers' costs are reduced because all crop is ready for harvest at the same time
- 'Refinement' of selective breeding
- Farmers' costs are reduced because all crop is ready for harvest at the same time
- Farmers know what the crop plant produced will be like because it it cloned from plants with known features
- Micropropagation is much quicker than selective breeding
- Huge numbers of genetically identical plants can be generated from small number of plants or a single valuable plant
- Farming methods now more regulated and (although genetically uniform plants still grown) areas given to specfic crops + distance between areas of same crop are controlled
- Limit effects of arrival of new pathogens
- Propagation using callus culture means:
- Disadvantages of plant cloning in agriculture
- Selective breeding over generations = reduced genetic variation
- Farmers identified + grown only crops with useful features
- Some fruit trees cannot be grown from seed because new tree will have combinstion of genes that not give correct fruit
- Genetic uniformity means all plants are equally susceptible to any new pest, disease or environmental change
- 1845-1851, Ireland: Potato famine 1 mill. ppl died from starvation + disease
- Potato crop lost due to infection by fungus-like protoctist
- 1845-1851, Ireland: Potato famine 1 mill. ppl died from starvation + disease
- Selective breeding over generations = reduced genetic variation
- USED FOR YEARS Artificial vegetative propagation - two main methods:
- Cloning Animals
- Artificial cloning - two ways:
- Splitting embryos
- 'Artificial identical twins'
- Cells from developing embryo seperated out, with each one going on to produce seperate (genetically identical) organism
- Nuclear transfer
- Using enucleated eggs
- Differentiated cell from adult taken + nuclus removed
- Nuclus placed in cell which had own nucleus removed
- Such a cell = enucleated
- Nuclus placed in cell which had own nucleus removed
- Dolly the sheep in 1996, 277 attempts
- Splitting embryos
- Only embryonic cells naturally capable of going through stages of developm. to generate new organism
- Totipotent stem cells
- Cloned animal is one that has been produced using the same genetic information as another animal
- Such an animals has same genotype as donor organism
- Advantages of cloning animals
- High-value animals (cows who give high yield milk) can be cloned in large numbers
- Rare animals can be cloned to preserve the species
- Genetically modified animals(sheep that produce pharmaceutical chemicals in milk) can be quickly reproduced
- Disadvantages of cloning animals
- High-value animals are not necessarily produced with animal welfare in mind
- As with plants, genetic uniformity in a species makes it unlikely to be able to cope with or adapt to changes in environment
- Still unclear whether animals cloned using nuclear material of adult cells will remain healthy in the long-term
- What is non-reproductive cloning?
- Developments in cloning = possibility of using cloned cells to generate cells, tissues + organs to replace those damaged
- Advantages of using cloned cells
- Being genetically identical to indiviv. own cells means will not be rejected because immune system will not recognise as foreign
- Cloning + cekk culture techniques could mean end to current problems of waiting for donor organs to become available for transplant
- Cloned cells = totipotent, so can generate any cell type. Damage by some diseases cannot currently be repaired by transplantation
- Using cloned cells less likely to be dangerous than major operation (e.g. heart transplant)
- Possibilities for non-reproductive cloning:
- Regeneration of heart muscle cells following heart attack
- Repair of nervous tissue destroyed by diseases such as multiple sclerosis
- Repairing spinal cord of those paralysed by accident (broken neck or back)
- Artificial cloning - two ways:
- Clones in Nature
- Advantages of asexual reproduction
- Quick, allowing organisms to reproduce rapidly + take advantage of resources in the environment
- Can be completed if sexual reproduction not possible
- All offspring have genetic information to enable them to survive in environment
- Identical twins
- Zygote splits in two - natural twins
- Clones = exact copies. Genetic cells or whole organisms that carry identical material because derived from same original DNA
- Disadvantages of asexual reproduction
- Does not produce any genetic variety - any genetic parental weakness will be in offspring.
- If environment changes all genetically identical organisms will be equally susceptible
- Does not produce any genetic variety - any genetic parental weakness will be in offspring.
- Natural vegetative propagation in plants
- English Elm
- Adapted to reproduce asexually following damage to the parent plant
- Allows species to survive disease or burning
- New growth (root suckers/basal sprouts) appear within 2 months of destruction of main trunk
- Suckers grow from meristem tissue in trunk close to ground - where damage least likely to have occured
- Adapted to reproduce asexually following damage to the parent plant
- Advantages to the elm of vegetative propagation
- Root suckers help the elm spread because they grow all around the original trunk
- When tree stressed or dies, circle of new elms grow = clonal patch
- This puts out new suckers so that the patch keeps expanding as far as resources permit
- Root suckers help the elm spread because they grow all around the original trunk
- Disadvantages to the elm of vegetative propagation
- 20th century, Europe: Dutch elm disease spread (fungal disease carried by beetle)
- Leaves withered, followed by death of branches and trunks
- Root suckers grew but died when 10cm diameter -> new suckers clones of original tree, no resistance against fungal attack
- No genetic variation within cloned population, so natural selection cannot occur
- Clones just as vulnerable as original tree
- 20th century, Europe: Dutch elm disease spread (fungal disease carried by beetle)
- English Elm
- Advantages of asexual reproduction
- Artificial Clones and Agriculture
- Clones in Nature
- Advantages of asexual reproduction
- Quick, allowing organisms to reproduce rapidly + take advantage of resources in the environment
- Can be completed if sexual reproduction not possible
- All offspring have genetic information to enable them to survive in environment
- Identical twins
- Zygote splits in two - natural twins
- Clones = exact copies. Genetic cells or whole organisms that carry identical material because derived from same original DNA
- Disadvantages of asexual reproduction
- Does not produce any genetic variety - any genetic parental weakness will be in offspring.
- If environment changes all genetically identical organisms will be equally susceptible
- Does not produce any genetic variety - any genetic parental weakness will be in offspring.
- Natural vegetative propagation in plants
- English Elm
- Adapted to reproduce asexually following damage to the parent plant
- Allows species to survive disease or burning
- New growth (root suckers/basal sprouts) appear within 2 months of destruction of main trunk
- Suckers grow from meristem tissue in trunk close to ground - where damage least likely to have occured
- Adapted to reproduce asexually following damage to the parent plant
- Advantages to the elm of vegetative propagation
- Root suckers help the elm spread because they grow all around the original trunk
- When tree stressed or dies, circle of new elms grow = clonal patch
- This puts out new suckers so that the patch keeps expanding as far as resources permit
- Root suckers help the elm spread because they grow all around the original trunk
- Disadvantages to the elm of vegetative propagation
- 20th century, Europe: Dutch elm disease spread (fungal disease carried by beetle)
- Leaves withered, followed by death of branches and trunks
- Root suckers grew but died when 10cm diameter -> new suckers clones of original tree, no resistance against fungal attack
- No genetic variation within cloned population, so natural selection cannot occur
- Clones just as vulnerable as original tree
- 20th century, Europe: Dutch elm disease spread (fungal disease carried by beetle)
- English Elm
- Advantages of asexual reproduction
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