- diabetes is a disorder where the glucose levels in the body is either too low or too high.
- can be treated by using insulin
- insulin allows the glucose to be taken up by the liver and other tissues, so cells get the glucose they need and blood glucose levels remain normal.
- natural insulin can be obtained from the pancreases of pigs and cattle. This can cause adverse reactions in some people, and supply is limited.
adverse means a negative outcome.
- most insulin is made using GM bacteria that have had the human gene for insulin inserted into them.
advantages of GM insulin over cattle insulin
- can be made in very large amounts from bacteria grown in fermenter
- less likely to cause an adverse reaction
- overcomes ethical concerns from vegeterians and some religious
making GM insulin
1.GM needs a DNA vector amd certain enzymes.
vector is the way in which genetic material is transfereed from a donor to a recipient eg, virus, bacteria, plasmids.
2. vectors take pieces of DNA and insert them into other cells, viruses and plasmids can act as vectors.
a virus is an ultramicroscopic infectious non-cellular organism that can replicate inside the cells of living hosts, with negative consequences.
plasmids are the small circular genetic material present in bacterial cells and used in GM.
3. restriction enzymes cut DNA at specific sites, and similarly ligase enzymes join pieces of DNA at specific sites.
restriction enzymes are enzymes that can cut DNA is specific places in the DNA molecule
ligase enzymes are enzymes that can join pieces of DNA together.
GM insulin production.
1. the gene for making insulin is cut from a length of human DNA using restriction enzymes
2. it is inserted into a plasmid using ligase enzymes.
3. the plasmid goes into a bacterial cell
4. the transgenic bacterium reproduces, resulting in millions of identical bacteria that produce human insulin.
- GM can be used to produce plants that improve food production eg. a plant with improved resistance to pests.
- there are also ethical issues: GM food may contain substances that can cause an allergic reaction, or high levels of toxin naturally found in the food.
a toxin is a type of natural poison produced by an organism, often as a form of protection.
- others think it may be wrong to create new life forms, or move genes between species.
herbicide resistant crops
- scientists have added genes to crops that make them resistant to herbicides.
herbicides are substances used to kill weeds
- this means less herbicide needs to be used
there are also disadvantages:
- potential development of herbicide-resistant weeds
- loss of bio-diversity because fewer weeds survive, resulting in reduced food and shelter for animals
bio-diversity means the range of plants and animals in the ecosystem.
cloning plants - cuttings
- clones are genetically identical individuals
- it allows a variety of plants to be produced cheaply, quickly and on a large scale
The simplest way to clone a plant is to use a cutting. A branch of the parent is cut off and the lower leaves are removed, then it is planted in damp compost.
the cutting is covered in a clear plastic bag to keep it moist and warm
after a few weeks new roots will develop and a new plant is produced.
cloning plants - tissue culture
tissue culture is the growth of tissues or cells seperate from an animal or plant.
this process can also be called micropropagation.
it works with small pieces of plants called explants. these are grown invitro (experiments that are done in glassware) using sterile agar jelly (growth medium), that contains plant hormones and nutrients.
This makes tissue culture more expensive and harder to do that cutings.