Gene transfer techniques- Plasmids and Balistic

1. Gene transfer techniques 
In the laboratory, specific enzymes may be used to cut and splice DNA:
Restriction enzymes break DNA at specific parts of the molecule (nucleotide base sequences) - usually leaving so called "sticky ends".
This can be done to both DNA from which genes are being taken, and to DNA in which genes are being inserted. Then, DNA ligase enzymes may be used to rejoin such sections into the other DNA.
The DNA containing the selected gene for the desired characteristic may then be inserted into cells of the target organism by means of vectors. There are 2 main types of vectors:plasmids and viruses (see previous notes on micro-organisms).

1.1 Gene transfer using plasmids 
Agrobacterium tumefaciens is a bacterium that contains a section of DNA called a plasmid in addition to its usual component of DNA. This tumour inducing plasmid has the ability to incorporate its DNA into the cells of the plant host, thus acting as a medium to allow the insertion of other genes into crop plants during genetic engineering.

1.2 Gene transfer using viruses
lambda (λ) phage - a bacteriophage which can modify bacteria, stays in the DNA of the host, and replicate the host’s DNA. It does not harm the host during the replication process, but it evolves with the host DNA. The microphage can remain inside the host indefinitely without having any harmful effect. These bacteriophages can be modified using restriction enzymes and foreign DNA. When the bacteriophages are opened, gene modification can be carried out by inserting the desired viral DNA to integrate with the host cells's "chromosome".

2. Others

2.1 Ballistic techniques
Minute tungsten particles are coated with the DNA to be inserted, then shot into the target cells with an explosive charge.

2.2 Electroporation
In this technique, a brief pulse of electric current is passed through the cell, temporarily increasing surface permeability so that DNA is taken up from the surrounding liquid. This has been especially useful with pollen tubes and has resulted in the genetic transformation of seeds.

author: Monica  

Health hazards

Health hazards of GM foods

There are various health hazards that can be contributed by GM food. There are a wide range of health hazards which are ranged from rashes to cancer. There are studies which prove that there is an increase in the risks for cancer, birth defects and other health effects which are linked to the use of super weed-killers. Glyphosate which is a broad spectrum herbicide which is commonly used in herbicide resistant crops are known to be possible hazards to health which is proven in an article from the year 1999.  It is proven via laboratory studies that adverse health reactions can be caused by glyphosate even at low doses. In an experiment done on animals, results show that glyphosate causes diarrhea, salivary gland lesions, liver damage and cataracts. There is also an increase in thyroid pancreas and liver tumors after the animals consumed products with doses on glyphosates in it.

Even though glyphosate in our food poses danger to human health, there is still a legal limit recommendation of dosage of 20mg per kilo of glyphosate residue in GM product which is given by the WHO (world health organisation).

 Bt which is known as bacillus thuringenesis is a natural insecticide which is used to spray on crops to control crop eating insects. Bt have poissibilities to cause intesitinal problems which can also lead to severe damage. This fact is not negligible as rats have been used during experiments to test for the health effects of Bt residues from the plantations. However the there are high possibilities that anyone who consumes an unacceptable dosage of bt will most likely suffer from diarrhea.

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Widening of social gap

Widening of social gap from the rich and poor

Qualities of GM seeds have been modified and their detriments may only occur throughout the years. Farmers are prone to pick the most efficient seeds which causes the planting of the same crops in all areas. By doing so, resistance to diseases will be reduced when crops were attacked. The same type of crops will be affected by the same disease and this may eliminate out all food supply. Other than that, the genetically modified seeds may widen the gap between the rich and the poor farmers. The poorer farmers will not be able to afford the more expensive genetically modified seeds thus causing them to stick to their old methods. The richer farmers therefore will use the new seeds and increase their yield and wealth thus increasing the disparity gap between the rich and the poor, genetically modified seeds will lead to an increase in the unemployment rate. Many will be jobless, further increasing the disparity gap. (Ngeography, 2007)

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Religious concerns and beliefs, ethical concerns

Religious concerns and beliefs

cows given more potent GM growth hormones could suffer from health problems related to growth or metabolism and lastly, new GM organisms could be patented so that 'life' itself could become commercial property through patenting. Usually, ministers, vegetarians and others will be found on either both sides of the debate regarding foods that were modified contain genes from animals or species that are prescribed by various religions. (Parker, 2003)

Ethical concerns

Crops are modified to provide immunization against common types of diseases, and crops are able to withstand particular growing conditions such as drought and soil acidity. Surpassing the benefits of GM crops could be counterproductive from an environmental associated with conventional agriculture.  GM crops can limit the need of chemical inputs such as pesticides, herbicide and fertilizers and can prevents further soil erosion and loss of moisture in vulnerable areas by reducing the need for ploughing (parker, 2003)

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consumer rights- outcrossing

defination:
Outcrossing

Outcrossing typically occurs accidentally, but poses a real health risk to consumers of genetically-modified crops. Outcrossing occurs when genetically-modified seed used to grow genetically-modified crops is mixed up with a conventional crop with the similar type of gene is transferred to the conventional crop. This becomes a problem since some crops are not safe for human consumption and are grown strictly for such things as animal feed. (Corp, 2011)

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The risk of Gene modification (at a glance)

Genetic engineering is capable of introducing dangerous allergens and toxins into foods (Mohan, 2005). As a gene is a building block for a protein, the introduction of a foreign gene that is not originally produced by the organism, will has the possibility of evoking an allergy that is not found in the conventional food crop (Wesseler, 2005).

This is because the cellular metabolisms are altered and may result in the production of dangerous by-products such as toxins and allergens. Furthermore, the newly-introduced protein may be enzymes that may interupt with the growing process of the food-producing organism, where the vitamins and mineral production may be short-changed (Mohan, 2005).

go to here to see the beenfits of gene modification

author: monica

Polymerase chain reaction (PCR)

The polymerase chain reaction (PCR) is a scientific technique in molecular biology to magnify and increase a single or a few copies of a piece of DNA across various extent, generating thousands to millions of copies of a particular DNA sequence (White, 1993). One of the major concept in PCR is thermal cycling, a process where the sample is heated and cooled alternately into a defined series of temperature steps.

During thermal cycling, two strands of the DNA double helix gets separated under high temperature. After heating, the sample is then cooled, where DNA polymerase uses each strand as a template to select the target DNA (Narayanasamy, 2010). The DNA polymerase used are also heat stable. An example will be Taq polymerase, an enzyme originally isolated from the bacterium Thermus aquaticus (Maier, 2009).

This DNA polymerase, through enzymatic action, assembles a new DNA strand from nucleotides (Mullis, 1994). This process is done by using single-stranded DNA as a template and DNA oligonucleotides, which are required for initiation of DNA synthesis (White, 1993). PCR is used in functional analysis of genes, the diagnosis of hereditary diseases and infectious diseases. PCR’s ability in targeting selected DNA also made this process widely used in genetic manipulation (Maier, 2009).

author: monica