When restriction enzymes cut up the DNA into fragments PLASMIDS are often used to combine with the fragments and then the recombinant DNA molecule can act as a vector carrying the DNA into the bacterium – an added advantage is the presence of genetic markers such as antibiotic – resistance genes that can be used for selection.
If the vector DNA and the target DNA are cut using the same restriction enzyme then their ‘ sticky ends’ will be complementary as a result they will tend to pair off.
The phosphate sugar back base, however, must be a joined and viral enzyme and ligases carry this out so restriction enzymes allow envitro recombination of DNA
Vector molecules can't replicate in a test - tube. They must be taken up by a cell where they will then replicate. E. Coli is the most widely used host by yeast. Mammalian cells can be grown in culture.
REVERSE TRANSCRIPTASE
Retroviruses contain the enzyme reverse transcriptase. This allows them to run the step of protein synthesis in reverse:
For example:
DNA - - - - - - - - - - - - - - - - > RNA - - - - - - - - - - - - - - - - - - - >
Transcription Translation (Protein)
They contain RNA and use the enzyme to synthesis DNA.
Microbes
Microbes make compounds called enzymes that we use in making hundreds of products. We grow billions of bacteria in giant fermenting tanks.
The bacteria is then broken up to get their enzymes to make soy sauce, soda, beer, wine, cheese, infant formula, chewing gum, leather goods, paper, the stone-washed look on blue jeans, etc.
Conditions of Microbes
Temperature:
It is necessary to retain, that in general, microbes develop well between 10°C and 45°C, the interval for which it is necessary to redouble vigilance in terms of food safety. Temperature is a very important factor and is often used by the food industry. Indeed, if we apply to food a very high temperature during a determined time, we can succeed in destroying the totality of the microbial germs: it is the process of sterilization.
Oxygen:
Some bacteria develop only in the presence of oxygen: they are aerobic. If it's necessary, we can kill them by packing the food under vacuum. The others are anaerobic and do not needed oxygen in the environment for their growth.
pH:
There are germs that prefer acid circles. The majority of the microorganisms don't develop below a pH 4,5. Their optimal pH of growth is 7. In the food industry, one can play on this factor by adding raw materials or additive allowing to reduce the pH of the environment.
Water:
The more the product is dry, the more its duration of conservation will be long.
Genetic Modification
Agriculture
Genetic Modification can also be known as genetically manipulating foods, in other words the plant has been changed by adding the genes from another plant. This can be an additional gene or many genes.
Plants are modified in order to give them immunity from certain predators.
Genetic modification can also produce crops. Modifying plant foods is not the only action taken by the food industry. Many animals are injected with hormones to produce more meat.
Some examples include:
- Cows – treated with hormones to increase their milk production
- Salmon – treated to increase their size
Agriculture is dependent on microbes to maintain a biological balance of the soil; thus, they are essential for the growth of crops. More than 1,000,000,000 microbes can be found in only 1 gram of soil. Of this number, there may be more than 10,000 different species.
Bacteria is the most numerous of the microbes. It breaks down organic matter and minerals into usable material for plants. Other types of microbes kill insects that are destructive to plants.
Medicine
Where antibodies are used in food production this could lead to immunity in those people who eat the food and many people have developed allergies. In some cases interfering with ‘ mother nature ‘ has arguably damaged the environment.
Many years ago people thought that illness was a judgment from a deity, or bad blood that needed to leave the body (hence the use of leeches), etc. We now know that many illnesses are caused by organisms--usually microscopic in size, collectively called microbes.
Fungi and bacteria produce powerful antibiotics such as penicillin. These are drugs we use to fight off nasty bacteria that cause sore throats, ear infections, diarrhoea and other discomforts.
Scientists have changed or engineered the genetic blueprints of bacteria and yeasts to turn them into mini medicine-making factories. They stick genes for medicines they want to make ( for example, insulin for diabetes ) into the microbial cells, as if adding new building information to the microbe's blueprint. The scientists then grow the microbes in huge containers called fermenters where they happily reproduce into billions, all making insulin.
Food
Recent advances in food and biotechnology have led to the development of new and improved food products. Different methods of food presentation e.g. fast freezing and freeze – drying have resulted in food having a longer shelf life. Food no longer needs to be consumed as soon as it is purchased or harvested. Whole ranges of food have thus become available to a wider population over an extended period of time.
Genetic engineering, a method of changing the inherited characteristics of organisms by altering their genetic composition, their DNA, has contributed to the development of new drug – resistant and past – resistant varieties of food.
Bread is made from grains fermented with yeast. The yeast produces the gas carbon dioxide (CO2) and the alcohol ethanol (CH3-CH2-OH). The carbon dioxide gas makes the bread rise. The ethanol evaporates during baking.
Yoghurt is made from fermented milk. Milk is rich in sugars, particularly the sugar lactose. Since microbes like sugars, milk is a great feast for microbes. Lactobacilli are the bacteria that convert milk to yoghurt. In the process of using the milk sugar, Lactobacillus produces acid which makes the yoghurt sour and a less hospitable place for other microbes.
Environment
Pesticides are used in food production and storage, forestry and even in domestic gardening on a large scale. They are chemical substances or in some cases micro – organisms, such as bacteria and fungi, that are mainly used to prevent the spread of pests and insect – borne disease amongst crop and plants.
Researchers have linked the problems with pollution in rivers and lakes and deformities in birds and animals to those areas where there is a high and sustained use of pesticides.
The problem that lies ahead is the potential dangers to the human population. There are many uncertainties regarding the long – term effects of the use of pesticides.
Advantages and Disadvantages of Genetic Engineering
During the 20th century man harnessed the power of the atom and not long after soon realised the power of genes.
Advantages:
- Disease could be prevented by detecting people, plants or animals that are genetically prone to certain hereditary diseases and preparing for the inevitable.
- Infectious diseases can be treated by implanting genes that code for antiviral proteins specific to each antigen.
- Animals and plants can be 'tailor made' to show desirable characteristics. Genes could also be manipulated in trees for example, to absorb more CO2 and reduce the threat of global warming.
- Genetic Engineering could increase genetic diversity, and produce more variant alleles, which could also be crossed over and implanted into other species. It is possible to alter the genetics of wheat plants to grow insulin for example.
Disadvantages:
- Nature is an extremely complex inter-related chain consisting of many species linked in the food chain. Some scientists believe that introducing genetically modified genes may have an irreversible effect with consequences yet unknown.
- Genetic engineering borderlines on many moral issues, particularly involving religion, which questions whether man has the right to manipulate the laws and course of nature.
Genetic engineering may be one of the greatest breakthroughs in recent history alongside the discovery of the atom and space flight, however, with the above eventualities and facts above in hand, governments have produced legislation to control what sort of experiments are done involving genetic engineering. In the UK there are strict laws prohibiting any experiments involving the cloning of humans.
