New Technologies B7

Bacteria are ideally suited for industrial and genetic processes

THIS IS DUE TO;

• RAPID REPRODUCTION - bacteria can double in number every 20 minutes

• THE PRESENCE OF PLASMIDS - circular DNA molecules that can be transferred easily between bacteria

• SIMPLE BIOCHEMISTRY - which makes the bacteria easier to understand and alter

• THE ABILITY TO MAKE COMPLEX MOLECULES - bacteria can produce molecules that can be used medicinally

• LACK OF ETHICAL CONCERNS - when using bacteria, people do not regard them as the same as higher-order animals such as monkeys

• Bacteria and fungi can be grown on a small scale in test tubes.
• By maintaining the ideal conditions for a micro organism, it is possible to expand the process to an industrial scale using the process of fermentation and a fermenter

WHAT IS A FERMENTER?

• A fermenter is a controlled environment that provides ideal conditions for micro organisms to live in, feed and produce the proteins needed

A fermenter allows the continous culture of large quantities of micro organisms or their products, namely;

• ANTIBIOTIC AND MEDICINAL PRODUCTS - it is possible to extract specific antibiotics and vaccines from bacteria and fungi grown in a fermenter
• SINGLE-CELL PROTEINS/HORMONES - insulin is a hormone that can be produced via bacteria in a fermenter
• ENZYMES FOR COMMERCIAL PRODUCTS - for example in biological washing powders that wash at 30°C - and biofuels such as ethanol
• ENZYMES FOR FOOD PROCESSING - for example chymosin, a vegetarian substitute for rennet, which is used to make cheese. Rennet is usually extracted from the stomach of animals. Tofu is another example of a food made using enzymes

WHAT IS THE LINK BETWEEN DNA AND PROTEINS?

DNA is the genetic material of all organisms and it contains the genes that code for the particular proteins an organism needs. Proteins produced by one organism may not neccessarily be produced by another.

WHAT CAN GENETIC MODIFICATION DO?

By carrying out genetic modification, the gene that produces a desirable protein can be inserted into another organism so that it also produces the required protein.

THE STEPS OF GENETIC MODIFICATION:

• Selection and isolation of the desired gene
• Replicate the gene, (copied exactly and increased in number)
• Gene inserted into bacterial DNA of target organism by a vector, (usually a virus or plasmid)
• Replication of the genetically modified organisms by bacterium which multiply rapidly

WHAT CAN IT BE USED FOR?

Genetic modification is now used to create an increasing number of drugs and hormones to treat humans

GIVE AN EXAMPLE?

• Genetically-modified micro organisms are used in the production of insulin for people with diabetes

• Until recently insulin was taken from pigs and cows, however it is now possible to use genetically-modified bacteria to produce human insulin instead

The vast majority of DNA is identical in all humans. In fact, humans share 99.9% of their DNA with chimpanzees.

WHY DO WE NEED DNA PROFILING AND WHAT ARE MICROSATELLITES?

• Identifying specific individuals, rather than a species, requires a more specific technique -DNA profiling. DNA profiling involves using specific areas of DNA that repeat regularly, called microsatellites.

• Although variable microsatellites are passed onto children. Everyone's microsatellites are different, a little like a fingerprint. This means that DNA profiling can be used to identify the paternity of a child or to identify the perpetrator of a crime

• DNA testing can also look for alleles of specific genetic disorders. This enables people to find out the chances of the inherting a genetic disorder and take action in advance.

HOW DO YOU EXTRACT DNA FROM CELLS?

• Genetic testing involes extracting the DNA from cells. In forensic science, these can be from any cell, (cheek, skin, hair etc). In a sampe of blood, DNA can be extracted and isolated from white blood cells.

• Enzymes and detergents are used to release the DNA. Once the DNA has been washed and non-DNA material removed, it is subjected to a process called polymerase chain reaction (PCR)

• PCR is used to amplify the sections of the genome that are being investigated. (i.e the microsatellies for identity or the gene alleles for disorders).

• PCR works by using the original DNA, as a template and adding new copies using the enzyme, DNA polymerase, and primers (building blocks of DNA)

• PCR is a chain reaction because once started, the DNA exponentially increases in quantity, so that in a short period of time, there is plenty of identical DNA for the geneticists to work with.

WHAT ARE GENE PROBES? AND WHAT DO THEY DO?

• Gene probes (markers) are created that are mirror copies 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.
• The samples are put into the cells of a polyacrylamide gel and an electric current is applied.
•  The DNA fragements in the sample move down the gel at a rate determined by their charge and mass. This means that the genes separate out. This process is called southern blotting. It is similar to the process of chromatography which separates pigments.
• Once separated, a special paper is placed on top of the gel. This absorves the pattern of DNA.
•  If the labelled genes or alleles were present in the DNA sample they would produce ultraviolet light, which can be photographed using sensitive film.
• To identify the genes it is usual to run a set of test DNA sequences. This enables the geneticist to work out the relative size of the molecules in each band and to check they are what they should be by looking at the relative position of the fluorescent band.

WHAT IS NANOTECHNOLOGY AND WHAT DOES IT PROMISE?

Nanotechnology promises to revolutionise bilogy. It is the application of matter on an atomic scale (i.e extremly small. between 1 and 100 nanometers, in at least one dimension). This is the same size as some molecules

HOW MANY NMs IN A MM?  there are 1 000 000 nanometers in a milimetre

APPLICATIONS OF NANOTECHNOLOGY;

• NANOPARTICLES - these can deliver chemotherapy drugs directly to cancer cells
• SILVER NANOPARTICLES - silver has antimicrobial properties. It would be extremely expensive to coat objects with silver, however it is cheaper using silver nanoparticles impregnanted into different materials. Example; deodorants and bandages have been developed with silver added to the, - the silver helps to kill micro organisms
• TISSUE ENGINEERING - this is where scientists are looking to alter biological processes on an atomic scale, (i.e manipulating individual atoms or creating nanomachines to carry out processes).

HOW DOES NANOTECHNOLOGY PLAY A ROLE IN THE FOOD INDUSTRY?

•  Nanotechnology is being applied to the food industry. Wasted food is a big problem, it may end up in landfill. Food has to be sold with a use-by date telling the customer when it should be eaten/ If the food is eaten after the given date it may have spoiled (i.e bacteria may have increased to an unsafe number)

• The use-by date is a scientific estimate, based on experiments, taken to see how long it takes the bacteria to reach unsafe levels. However, as a precaution and because each batch of food varis, the use-by date is earlier than it could be.

• Nanosensors are now being developed that can be incorporated into packaing. The sensors change colour when they detect the gases that are produced when food goes off. Oxygen is a very reactive molecule that can cause rapid food deterioration. Manufactureres prevent this by filling food bags with iner nitrogen gas. The nanopatricles can be incoropated into the packing to prevent oxygen entering.

EXAMPLES OF BIOMEDICAL ENGINEERING?

• Scientists and engineers are becoming more efficient at designing and creating replacement organs and pody parts.
• This includes replacing faulty heart valves and designing pacemakers, that keep the heart beating when the heart's synchronisation of beating muscle fails.

CAN THERE BE ANY PROBLEMS?

• Yes, replacement parts such as these have to be designed exceptionally well, as they have to work perfectly on a daily basis over many years and decades, so if there is a problem it can be potentially fatal

WHAT CAN THEY DO?

• Stem cells can be used to reverse damage to the body.

HOW CAN THEY HELP TREAT LEUKAEMIA?

• Stem cells can help to treat Leukaemia, a disease that kills white blood cells.

• Blood cells are made from the body's own adult stem cells in the bone marrow (found in the centre of some bones).

• Traditionally a leukaemia patient would need to have their own bone marrow removed and replace with that from a tissue-matched donor.

• However, using stemm cells that have been harvesterd (or genetically manipulated) from the patient's own body has a significant advantage. It means that the patient has a new complement of blood cells that are genetically the same as him/her/ This reduces the need for a bone marrow transplant - which carries the risk of rejection