This technique can be very useful, an example of how is insulin. Insulin is a hormone released by the pancreas to control blood sugar levels and when it enters the liver, converts the excess soluble glucose to an insoluble form called glycogen, it is then stored in the liver and muscles. When a person does not produce enough or any insulin they suffer from a condition called diabetes. They then must inject themselves with the hormone to prevent their blood sugar levels from getting to high. Scientists used to obtain insulin from the pancreas of slaughtered animals but the demand for insulin has become too high. Now scientist use genetically modified bacteria. The gene that produces insulin is extracted out of the human pancreas using enzymes. Enzymes are then used to cut open the plasmid (bacteria do not have a nucleus so their DNA is found in the plasmid) in the bacteria to make room for the insulin gene. The gene is then inserted. Bacteria are very useful for this because they divide every half an hour so create vast majorities of the insulin.
Genetic Modification (GM)
Genetic Modification means inserting genes from organisms to other organisms or even crops to make them produce vast volume of insulin or even creating crops which are resistant to herbicides and insecticides. The first genetically modified crop was the potato in the 1980’s. An insecticide production gene from a bacterium, which grows in soil, was inserted into the potato to make it become resistant to insect pests. More commonly resistance to herbicide modification has been introduced. This is because it is very difficult for farmers to kill weeds using herbicide without killing the crop plants as well. Scientists have recently extracted a herbicide resistant gene from bacterium which grows in soil, into the crops, making them resistant to herbicides.
Advantages and disadvantages of Genetic Modification
Advantages
- We can produce crops with high yield e.g. produce more fruit etc.
- It reduces the cost of production of crops etc.
- Better texture, flavour and nutrition.
- Resistance to insects, herbicides and disease.
- Increases insulin production when we genetically modify bacteria.
Disadvantages
- It can cause stress for the animals that undergo GM.
- It could influence the beginning of ‘Designer Babies’.
- Biotechnologists could be seen as ‘playing God’
- Genetic engineering is unnatural.
- We don’t know the long term affects of new organisms on humans.
Cloning
The natural form of cloning occurs in asexual reproduction. This is when a cell divides to form two cells identical to each other and to the original cell, in mitosis for example. This can occur in bacteria and other organisms. There also artificial cloning. The difference between asexual and sexual reproduction is that in asexual offspring are produced from one parent and are identical to each other and the parent, also only one parent is involved. In sexual reproduction two parents are involved and offspring produced are different to each other (unless they’re identical twins) and to the parents. This has an advantage as there is variation.
Cuttings
This is when farmers take cuttings from a plant and then growing new plants from these cuttings so they are clones of the parent plant. This is a quick and cheap process; however it reduces the number of alleles in the gene pool-no variation.
Tissue Culture
This is when few cells are taken from part of a plant and grown in an agar jelly to form a copy of the parent plant. Advantage is that they can grow quickly and take up little space but the number of alleles in the gene pool reduces
Splitting Embryo’s
This usually occurs in horses and cows. For example sperm cells are taken from the bull and scientists freeze them for a later date. The cows are then fed hormones to make them produce vast amount of eggs, and these removed. The sperm cells then artificially fertilise the egg cells. The fertilised egg cells then grow into embryos. Scientists then screen the embryos for the sex, genetic defects and they then split these embryos into individual cells. These cells will then grow into embryos and are clones of each other but not to the parents. These embryos then grow inside surrogate cows or are frozen to be used later. An advantage is that we can grow prize cows all year however it is more likely for the offspring to have genetic diseases as the number of alleles in the gene pool decreases.
