B7.5 New technologies
The features of bacteria that make them ideal for industrial and genetic processes include:
- Rapid reproduction
- Presence of plasmids – circular DNA molecules that can be transferred easily between bacteria
- Simple biochemistry – easy to understand and alter
- Ability to make complex molecules – bacteria can produce molecules that can be used medicinally
- Lack of ethical concerns in their culture
Many useful products are made by fermentation – which involves growing bacteria or fungus (e.g. yeast) on a large scale. Some of these useful products include:
- Antibiotics and other medicines
- Single-cell protein – such as mycoprotein which is used in meat substitute products
- Enzymes for food processing, for example chymosin as a vegetarian substitute for rennet
- Enzymes for commercial products, such as washing powders and to make biofuels
In genetic modification, a gene is transferred from one organism to another where it continues to work
- Isolation and replicating the required gene
- Putting the gene into a suitable vector (virus or plasmid)
- Using the vector to insert the gene into a new cell
- Selected the modified individuals
Examples of the application of genetic modification include:
- Bacteria synthesis of medicines e.g. insulin
- Herbicide resistance in crop plants – by creating crops with resistance to a herbicide, the farmer can use that herbicide to kill weeds without destroying the crop
Genetic testing may be used to find out if an individual has a genetic disease – a disease which they have inherited and which is a result of a defect in their DNA
To investigate a person’s DNA, white blood cells are used because they are easy to obtain from a blood sample, and unlike red blood cells they have a nucleus containing the DNA.
- Isolation of DNA from white blood cells
A small quantity of blood has chemicals added it – the chemicals split open the red cells
The DNA is collected and then replicated (more copies of it are made) so that there is enough to test. The DNA is then broken up into smaller sections using enzymes and put onto a special gel. An electrical current is applied, and the pieces of DNA separate out along the gel.
- Gene probe (marker)
Gene probes are created that are mirror copied of the target allele or microsatellite region – the gene probes are attached to a fluorescent chemical that emits ultraviolet light. If the target segment of DNA is present in the DNA sample, the gene probe will attach to it
- Adding the gene probe to the sample DNA
The separated pieces of DNA on the gel are ‘blotted’ to split the DNA into single strands. The gene probe is added and if the gene the scientist is searching for is present, the gene probe will bind to it because it has a complementary base sequence to the gene being investigated. This process is called Southern blotting
- Using UV light
The gel is then viewed under UV light. If the gene is present, the gel will glow at that point. The gene has therefore been identified as being present in the person’s DNA.
Nanotechnology means manipulating and using particles of materials that are very small – about the size of some molecules.
Nanotechnology can be used in food packaging. For example, silver nanoparticles are anti-microbial and can be used to prevent harmful bacteria from growing inside food packaging. This extends the shelf life of the food.
Nanotechnology can also be used to build biosensors into packaging. These help to identify when food has started to deteriorate as a result of microorganisms releasing harmful substances as they break down the food.
Stem cells are being used to reverse damage to the body
Leukaemia – stem cells can help to treat leukaemia, a disease that kills white blood cells – traditionally a leukaemia patient would need to have their own bone marrow removed and replaced with that from a tissue-matched donor
However, using stem cells that have been harvested from the patient’s own body has a significant advantage – it means that the patient has new complement of blood cells that are genetically the same as him/her
Biomedical engineering involves solving medical problems using new materials and man-made parts.
The human heart has its own pacemaker, which sends an electrical signal to the heart muscle cells that makes them contract at the right time. In some people, this natural pacemaker doesn’t work properly. Doctors can insert an artificial pacemaker into a patient’s chest which controls the contraction of the heart.
Heart valves can sometimes become faulty. If this happens it can stop the heart from effectively pumping blood to the lungs and body.
Doctors can now replace faulty heart valves with artificial valves. To do this the patient must first be connected to a heart-lung machine to maintain circulation. The heart is then stopped by the surgeon, cut open, and the damaged valve is replaced.