1. Drugs
-P.W

2. Drugs and Disease
Imbalances in some neurotransmitters may contribute to disorders:Parkinson’s Disease
→ Brain disorder that affects the motor skills (movement), the neurons that control movement in the brain are destroyed
→ The neurons for movement normally produce the neurotransmitter dopamine, therefore losing them causes lack of dopamine
→ Lack of dopamine causes a decrease in the transmission of the nerve impulses involved in movement leading to tremors and slow movement
→ As we know the symptoms are caused by a lack of dopamine, we can use drugs that increase dopamine levels in the brain to reduce the symptoms
Depression
→ There may be a link between a low level of the neurotransmitter serotonin and depression
→ Serotonin transmits nerve impulses across synapses in the parts of the brain that control mood
→ As we know symptoms are caused by low levels of serotonin, we can use drugs that increase levels of serotonin in the brain to reduce the symptoms

3. Drugs and Disease Drugs affecting synaptic transmission L-dopa
→ We can use L-dopa to treat parkinson’s disease, the chemical structure is very similar to dopamine
→ L-dopa is absorbed into the brain and converted into dopamine by the enzyme dopa-decarboxylase (dopamine cannot be absorbed directly into the brain as it cannot cross the blood-brain-barrier), therefore increasing dopamine levels in the brain
→ Higher levels of dopamine mean that more nerve impulses are transmitted across the synapses in parts of the brain that control movement, giving the sufferers of the disease more control over movement
MDMA
→ Increases serotonin levels
→ In normal circumstances, serotonin is taken back into the presynaptic neuron after triggering an action potential to be used again
→ MDMA increases levels of serotonin by inhibiting the reuptake of serotonin into the presynaptic neurons, and also by triggering the release of serotonin from presynaptic neurons
→ This means that nerve impulses are constantly triggered in postsynaptic neurons in parts of the brain that control mood, therefore the effect is a mood elevation

4. Drugs and Disease Synthesising new drugs
→ The Human Genome Project (HGP) was a 13-year long project that identified all the genes found in human DNA (human genome). This information is stored in a database
→ We can use this information to identify genes and proteins that are involved in disease. We can create new drugs that target specific proteins (e.g we have identified an enzyme which helps cancer cells spread around the body, a drug which inhibits this enzyme is being produced)
→ We have identified common genetic variations between people and know that some drugs are less effective on people with particular mutations
→ Drug companies can therefore synthesise new drugs to target these people with these mutations
Moral and ethical issues
→ Creating new drugs for people with specific mutations will increase research costs of companies, rising the price of new drugs (the new drugs may only be available to richer people)
→ People may be refused drugs as their genetic make-up indicates the drug won’t be effective in them
→ Information within a person's’ genome could be used by other people and organisations, for example insurance companies and employers, this could lead to unfair discrimination against them
→ Revealing a drug may not work with that person may be psychologically damaging to them, especially if it is the only treatment available to them

5. Producing drugs using GMOs
Producing drugs using Genetically Modified Organisms (GMOs)
→ GMOs are organisms that have had their DNA altered, they can be specifically modified to produced proteins used as drugs
1. Genetically modified microorganisms
→ Process of how microorganisms are genetically engineered to produce drugs:
1. Gene for protein (drug) is isolated using enzymes called restriction enzymes
2. Gene is copied using PCR
3. Copies of gene inserted into plasmids (circular molecules of DNA)
4. Plasmids transferred into microorganisms
5. Modified microorganisms grown in large containers, allowing them to divide and produce the useful protein from the inserted gene in large amounts
6. Protein purified and used as a drug
→ Drugs like human insulin and human blood clotting factors are produced using GMOs
2. Genetically modified plants
→ Process of how plants are genetically engineered to produce drugs:
1. Gene for protein (drug) inserted into bacterium (same method as above with plasmids)
2. Bacterium infects plant cell
3. Bacterium inserts gene into plant cell DNA, plant cell is now modified
4. Plant cell is grown into an adult plant, the whole plant now contains copies of this gene, in every cell
5. Protein produced from the gene can be purified from the plant tissues, or the protein (drug) could be delivered by eating the plant
→ Drugs like human insulin and the cholera vaccine are produced using GMPs

6. Producing drugs using GMOs
3. Genetically Modified Animals
→ Process of how animals are genetically engineered to produce drugs:
1. Gene for the protein injected into nucleus of a fertilised animal egg cell
2. Egg cell is implanted into adult animal, growing into a whole animal that contains a copy of the gene in every cell
3. Protein produced from the gene is purified from the milk of the animal
→ Drugs like human antithrombin have been produced from genetically modified goats
Benefits and risks of GMOs
Benefits
→ Agricultural crops may be modified giving a higher yield or more nutritious crops, reducing the risk of famine or malnutrition
→ Crops can be modified to be pest resistant, reducing needs of using pesticides. This can reduce costs and make food cheaper, it also reduces environmental problems with using pesticides
→ Enzymes may be produced using GMOs in large quantities for less money for industrial processes
→ Some disorders can now be treated with human proteins from GMOs instead of using animal proteins, which are more effective and safe. (e.g type 1 diabetes used to be treated with cow insulin, now it is treated using human insulin, some people had a reaction to cow insulin)
→ Vaccines produced in plant tissues do not need to be refrigerated, therefore making them more available to more people in areas where refrigeration isn’t available
→ Producing drugs using plants and animals would be very cheap because once the plants or animals are genetically modified, they can be reproduce using conventional farming methods, this could make drugs more affordable for many people, especially in poor countries
Risks
→ The concern about the transmission of genetic material is a huge risk. If the resistant crops interbreed with wild plants like weeds, it could create herbicide-resistant weeds, super-weeds. Also people may end up eating drugs that they don’t need
→ Unforeseen consequences are also a risk, we don’t know the long-term impacts of using GMOs
→ Some people think it is ethically wrong to modify animals for human benefit