Plants are essential to life on earth because they capture light energy and convert it into a form - chemical energy - usable by all organisms. Taking the simple molecules carbon dioxide and water, they convert these into a wide range of energy-rich organic substances to serve their needs but which also fulfil the needs of other organisms.
All organisms are made up of the same basic biochemicals, so plants are a ready source of these staple foods - carbohydrates, proteins and fats, along with other essential nutrients such as vitamins and minerals. Of the plant species named to date (over 270 000), about 80 000 plants are known to be edible but only around thirty of these are grown as crop plants - wheat, rice, maize and potatoes provide more of the world's food than all other crops combined.
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As well as these staple foods, plants produce thousands of more subtle chemicals which man and other organisms have made use of. These include herbs, spices and fragrances, drinks, textiles, construction materials, dyes, fuels and medicines. Many new, revolutionary treatments, and hopes for the future, of diseases such as cancer are derived from plants, e.g. taxol from the Pacific yew.
Products from Micro-organisms
We know that micro-organisms were first used in brewing and baking in ancient Sumeria about 6000 years ago.
The first micro-organisms were observed by Anton van Leeuwenhoek in the mid seventeenth century, but the involvement of micro-organisms in brewing was not recognised until the work of Louis Pasteur in 1856.
Nowadays many products are produced using micro-organisms, including foods (beer, bread, cheese, yogurt, Single Cell Protein, e.g. Quorn, medicines (e.g. antibiotics such as penicillin) and using chemicals that micro-organisms produce as sources of energy (e.g. methanogenic and other bacteria producing "biogas", ethanol). It is the chemicals that the micro-organisms produce as part of their metabolism that make them useful.
Applications of Biological Systems and Processes
As biotechnology has advanced, biotechnologists have not only made use of the organism themselves, but biological systems and processes. These technologies make use of DNA:
* Enzymes: Enzymes are chemicals which speed up biological reactions. The use of enzymes by humans really began thousands of years ago, but when they were in the cells of organisms. More recently it has been realised that these would work better isolated from cells. Probably the first use of isolated enzymes was "takadiastase" - prepared from a fungus on wheat bran.
* DNA fingerprinting: Each individual on the planet (except for identical twins) is unique because of the combination of their genes and differences in large areas of the DNA that do not carry genes. In the early 1980s, Professor Alec Jeffreys, at the University of Leicester, showed that DNA, extracted from an individual could be broken into sections using enzymes, then separated into bands using a technique called electrophoresis. Because of similarities and differences in banding patterns, this technique can be used in forensic science, questions of paternity and in the diagnosis of genetic diseases.
Application of Enzymes
Applications of enzymes nowadays include:
* Industrial applications: Enzymes from bacteria which help to break down proteins and fats are used in biological washing powders. Dish washer powders often contain amylases to break down starch.
* Food industry: Many enzymes are used in the production of cheese and by some brewers in beer production. In baking, amylases are added to flour to speed up the breakdown of starch into glucose, for use by the yeast.
* Textiles: Starch has been used as a coating on fabrics to prevent damage during weaving. This can be removed by bacterial amylases.
* Medicine: Biosensors can be used, for instance, to test a person's blood cholesterol. Strips impregnated with enzymes are used to test for glucose, for instance in urine.
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