Biotechnology and Food Production
Biotechnology - the use of organisms, parts of organisms, or the processes the organisms carry out, to produce useful products, such as chemicals and foods.
Different microbes (can only be seen with a microscope) can be used to make foods, such as yoghurt and soy sauce.
Food Production - Probiotics and Prebiotics
Probiotics - living and beneficial bacteria that we ingest, found in foods like sauerkraut and yoghurt.
Prebiotics - non-digestible functional foods which stimulate the growth and metabolism of some beneficial bacteria found naturally in the human colon like lactobacillus and bifidobacterium. Examples of prebiotics are:
Oligosaccharides - naturally found in onions, eeks and other legumes, they are short-chain carbohydrates (4-20 simple sugars (monosaccharides) joined together in a long chain). They stimulate the growth of beneficial bacteria in the large intestine.
Plant stanol esters - naturally found in very small amounts but produced commerically by using bacteria to convert plant sterols (type of fat) into stanols. Plant stanol esters can lower cholesterol, reducing the risk of heart disease. Food manufacturers add them to products like spreads to promote them as healthy.
Food Production - Making Yoghurt
1) Milk is heated to 40C to sterilise it and get rid of unnecessary bacteria.
2) Milk is stirred to mix ingredients.
3) Milk protein is added.
4) Lactobacillus bacteria is added, which fermentsthe lactose sugar found in milk and turns it into lactic acid.
5) The lactic acid lowers the pH of the milk, causing the milk proteins to coagulate and giving yoghurt its sharp taste.
6) This is now raw yoghurt, to either be packaged and sold as it is or first flavoured.
Food Prodcution - Making Soy Sauce
Making Soy Sauce
1) Soya beans are cooked to kill the bacteria on their surface and then mixed with ground, roasted wheat.
2) The mixture is fermented by aspergillus ( a fungus) - it is spread on warm, shallow trays and supplied with air. This produces enzymes which break down proteins and carbohydrates, increasing the amino acid and sugar content.
3) Brine is added to give the soy sauce its salty taste and help preserve it.
4) Fermented a second time by yeasts and then lactobaccillus which use the sugars made previously.
5) The soy sauce is filtered to remove particles then pasteurised at 72C to kill unwanted microorganisms, before being bottled in sterilised bottles.
Using Microbes to Alter Food
Microbes are used in the industry to make chemicals that are added to food. This is done in order to prolong shelf life; improve flavour; improve texture; improve appearance.
Such chemicals products are known as microbial products. Examples are;
Vitamin C (E300) - produced using Acetobacter spp. (bacterium), increases shelf life of food containing fats.
Carrageen (E407) - produced using Carrageen spp. (seaweed), a gelling agent that thickens foods, gives them body. A vegetarian alternative to gelatine, which is made from animal bones.
Citric Acid (E472c) - produced using Aspergillus niger (fungus), added to fizzy drinks to give them their sharp, acidic taste.
Using Microbes to Alter Foods
More Microbial Products
Amino Acids, e.g. Glutamic acid - produced using Corynebacterium glutamicum (bacterium). Neutralisation of this acid makes sodium slat monosodium glutamate, a flavour enhancer for processed foods like sausages and pies.
Invertase (enzyme) - produced using Saccharomyces cerivisiae (yeast type). Invertase breaks down sugar sucrose into fructose and glucose. It is used to make soft centres in chocolate covered sweets.
Glucose isomerate enzyme converts glusoce into fructose which is sweeter.
Making Vegetarian Cheese
Cheese is made when the enzyme chymosin acts on milk. Originally it was obtained from the stomachs of slaughtered cows, in rennet ( a mixture of two proteins). The enzyme caused milk to form curds (raw cheese) and whey.
However, now chymosin can be produced very quickly through genetic engineering - bacteria are genetically modified to produce it. The gene responsible for chymosin was isolated and transferred to yeast cells.
This means vegetarians can eat cheese produced without using animal products (except milk).
A balanced diet includes a range of foods, and it is important to eat one in order to provide the body with the energy and nutrients it needs to work properly.
A balanced diet includes all the basic food groups (below) in the correct proportions for a certain individual. It depends on age, gender and level of activity.
Carbohydrates - from potatoes, rice, pasta. For energy (respiration) Proteins - from fish, lean meat, pulses. For cell growth and repair, energy. Fats - from whole milk, butter, cheese. For energy, insulation. Vitamins - from fresh fruit (C), fish oil (D), vegetables (A). For general health. Minerals - from fresh fuit and vegetables, meat, eggs. For healthy development of teeth and bones. Fibre - from nuts, pulses, fresh vegetables. For digestion - fibre keeps food moving through intestines, preventing constipation. Water - from drinks, fresh fruit and vegetables. For digestion - water keeps the body's metabolism working properly.
If you don't eat a balanced diet the body will lack nutrients. In extreme cases this can lead to illnesses, e.g.
Anorexia nervosa - occurs when person eats too little, will become underweight, possibly moody and weak. Increased risk of osteoporosis, anaemia, and other illnesses because their immune system is weakened.
Obesity - occurs when person eats too much fatty food and/or doesnt exercise enough, increased risk of arthritis, high blood pressure, heart disease and diabetes.
Body mass (kg) / body height^2 (m) = BMI
World Food Supply
Some parts of the world, particularly developing countries, experience food shortages for reasons such as the environment (conditions like poor soil and water shortages), poverty (too poor to buy food, land or equipment), or conflict (prevent distribution of food).
Biotechnology produces substances, including foods, that help food grow. Therefore, it has to potential to aleviate food shortages in many parts of the world.
Breeding Herbicide-Resistant Crops
Herbicides are used to kill weeds, but may also kill the crop. If crops are resistant, more food can be produced.
1) Scientists find a naturally occuring plant resistant to the herbicide.
2) They identify the gene responsible for resistance.
3) A vector such as the bacterium Agrobacterium tumefaciens is used to transfer the gene which codes for herbicide resistance into the embryo crop genome.
4) The crop plants are allowed to grow and when treated with the herbicie, are resistant.
Breeding Insect-Resistant Plants
the bacterium Bacillus thuringiensis produces a toxin that kills many insects. The gene responsible can be identified and transferrred into the genome of crop plants, making them resistant to insect pests.
1) The gene responsible for producing the toxin is identified.
2) It is transferred using a vector into the embryo crop plant's genome.
3) The new crops grow and are resistant to insect pests.
The Ethics of Biotechnology and Genetic Modificati
Some people believe this will help alleviate the world food shortage problem. However others argue it is a political/economic problem, and biotechnology is too new new, uncertain and untested to be relied upon. They think rich nations should spend money on transporting food to where it is neede.
Using this to ensure maximum food production is a controversial process. Scientists and others are concerned about whether there could be any long term problems with eating GM foods, and if they will spread their genes to other organisms. The main question is, what are the risks?
Choosing the Sex of a Baby
Genetic advances have made it possible to choose the sex of a baby, however people feel this goes against nature and object on religious or ethical grounds. They also worry it will skew the world population balance of sexes.
This is part of the 'designer babay' debate. It could lead to parents choosing everything, from eye and hair colour to intellectual and musical ability.
These objections make it difficult for scientists and doctors to have such advances approved.
Stem Cells and Parkinson's Disease
Stem cells are undifferentiated cells that can change into any type of specialised cell. When different chemicals called growth factors are added to they, they are made to develop into different cell types, e.g. insulin producing cells in the pancreas, heart muscle cells, blood cells, bone marrow cells and neurones.
This is where neurones in the brain stop producing dopamine, which is a chemical they use to communicate with eachother. When it is not produced, the brain cannot coordinate body movements and other things.
If stem cells could be made into brain neurones that produced dopamine, this could potentially be a cure for Parkinson's disease.
This is the study of an organism's entire genome. Biotechnology uses it to develop new medicines, e.g. in the production of blood clotting factors (special enzymes).
Haemophiliacs do not make these factors so they continue to bleed when they cut themselves. Blood clotting factors can be produced safely and efficiently in the milk of a sheep that have been genetically coded for the human version of the missing protein.
Other examples of genomics and biotechnology working togethere are:
- in the production of human protein interferon, which prevents viruses from multiplying inside the body.
- in the production of human growth hormones to treat abnormal growths
- to produce human insulin
The Production of Insulin
1) the gene for insulin is identified and removed using a restriction enzyme which cuts through DNA strands in specific places.
2) Another restrictio enzyme is used to cut open a plasmid. Other enzymes are used to insert the section of human DNA into the plasmid.
3) the plasmid is inserted into a bacterium which starts to divide rapidly, replicating the plasmid, before they begin to produce insulin. This final stage is done in fermenters.
This process means insulin can now be produced quickly and in large quantities. Previously used bovine insulin was not 100% effective and there were side-effects, including BSE being passed on to humans.
Medicines From Plants
Many medicines are now made synthetically but still originate from plants. People have known the importance and medicinal value of drugs for a very long time.
Plant substances fall into two groups: -Substances which affect the nervous system (morphine, curare, cocaine) -Substances which control a variety of heart problems ( e.g. digitoxin)
Curare is sourced from the strychnos plant in the amazon rainforest. Hunters used to put it on the tips of blowdarts before shooting birds, and the muscles which controlled breathing would stop working so the animal would suffocate and fall. Now it is used in operations in low doses to relax the patient's muscles to make it easier to control breathing.
50% of all drugs that fight disease cannot be synthesised, and must be sourced directly from the plant. Anti-cancer drugs (vinblastine, vincristine) are sourced from the rosy periwinkle in tropical rainforests.
Aspirin is produced from the active ingredient salicin, which can be extracted from the bark and leaves of a willow tree. It can be used to produce salicylic acid, which is a more effective painkiller than salicin, however it can irritate the stomach lining.
Aspirin contains a version of salicin which does not have any adverse side effects.
It treats pain and fever, stops the formation of blod clots and reduces swelling of both bones and tissues.
Aspirin is not a natural substances, unlike salicin it has been synthesised.
Taxol is an anti-cancer drug derived from the bark of pacific yew trees.
Taxol stops cancerous cells from dividing, making them die. However the pacific yew tree is a protected species and one of the slowest growing trees in the world, so only a small amount could be extracted, killing the tree at the same time.
A similar substance was found in the needle-like leaves of the european yew tree, and this was chemically modified to form a semi-synthetic version of taxol called paclitaxel. european yew trees replace ther leaves quickly, so large amounts can be extracted without affecting the number of trees. however it is an expensive process.
Quinine is an active ingredient that is extracted from the bark of a cinchona tree. It is used as an anti-malarial drug as it can kill plasmodium.
Malaria is caused by single-celled parasites called plasmodium, which enter the blood and can attack red blood cells. It is carried by female anopheles mosquitos.
Quinine works by lowering the body temperature and killing the parasites in red blood cells.
WW2 cut off quinine supplies so chloroquine was developed - it was more effective and easier to make so used instead, but some strains of the parasite are resistant to this drug so quinine is used again.
Artemisinin is sourced from the chinese plant Artemisia annua. It kills plasmodium (parasite that causes malaria) and prevents it from reproducing inside the malaria vector.
It i only active for a few hours in the body so is combined with other anti-malarial drugs, and used where resistance to chloroquine has developed.
Shortages have led to people attempting to create it in labatories. Genetically engineered yeast cells create a substance similar, and easily converted into artemisinin. Trials show that this substance is more effective and cheaper than the product itself.
It may also be used to treat cancer as it can kill cancerous cells and slow the development of vessels that supply oxygen to cancerous tissues, starving it of oxygen so it dies.