girl in the donut factory

brennagh, beegeok, yanfen, yongren, yapmin and shixuan=)

e diel, 17 qershor 2007

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Microbiological techniques isolation and identification of foodborn pathogens

-What are the principals? (examples of techniques)
e.g. immunoassay and DNA probes.

e diel, 10 qershor 2007

Molecular markers and MAS used

Molecular markers are identifiable DNA sequences, found at specific locations of the genome and associated with the inheritance of a trait or linked gene.

Molecular markers can be used for
(a) marker-assisted breeding,
(b) understanding and conserving genetic resources and
(c) genotype verification.

Genetic linkage maps can be used to locate and select for genes affecting traits of economic importance in plants or animals. The potential benefits of marker-assisted selection (MAS) are greatest for traits that are controlled by many genes.

Markers can also be used to increase the speed or efficiency of introducing new genes from one population to another, for example when wishing to introduce genes from wild relatives into modern plant varieties. When the desired trait is found within the same species, it may be transferred with traditional breeding methods, with molecular markers being used to track the desired gene.

Genetic engineering can be used when insufficient natural variation in the desired nutrient exists within a species. Biofortification (the development of nutritionally enhanced foods) can be advanced through the application of several biotechnologies in combination. Genomic analysis and genetic linkage mapping are needed to identify the genes responsible for natural variation in nutrient levels of common foods. These genes can then be transferred into familiar cultivars through conventional breeding and MAS or, if sufficient natural variation does not occur within a single species, through genetic engineering. Non-transgenic approaches are being used, for example, to enhance the protein content in maize, iron in rice, and carotene in sweet potato.

The State of Food and Agriculture 2003-2004

Genetic engineering using bacterium species

Genetic engineering differs from conventional plant breeding. In conventional plant breeding half of the genes of an individual come from each parent, whereas in genetic engineering one or a few specially selected genes are added to the plant genome.

Moreover, conventional plant breeding can only combine closely related plants.
Genetic engineering permits the transfer of genes between organisms that are not normally able to cross breed because they are not genetically compatible. The transferred genes are called transgenes. They can come from another plant species, or even from a completely different organism (e.g., bacterial genes). These transgenes are then replicated and inherited in the same way as natural plant genes.

When the desired trait is found in an organism that is not sexually
compatible with the host, it may be transferred using genetic engineering.

There are 2 ways of genetic engineering, i.e. biologically, and physically.

Biologically, in plants, the most common method for genetic engineering uses the soil bacterium Agrobacterium tumefasciens as a vector. Researchers insert the desired gene or genes into the bacterium and then infect the host plant. The desired genes are transmitted to the host along with the infection. This method is used mainly with species such as tomato and potato.

In the most common transformation technique for these crops, physical means are used. The desired gene is coated on gold or tungsten particles and a “gene gun” is used literally to shoot the gene into the host at high velocity. Once the DNA reaches the cell nucleus, it inserts itself at random into one of the host chromosomes and can express the desired character. The genetically modified plant is then grown from the transformed cell.

Overview of how transgenic crops are created:

When the
bacterium infects the plant, it penetrates the plants cells and transfers its modified DNA to the plant.

Three distinctive types of genetically modified crops exist:
(a) “distant transfer”, in which
genes are transferred between organisms of different kingdoms (e.g. bacteria into plants);
(b) “close transfer”, in which genes are transferred from one
species to another of the same kingdom (e.g. from one plant to another); and
(c) “tweaking”, in which genes already present in the organism's
genome are manipulated to change the level or pattern of expression.

Once the
gene has been transferred, the crop must be tested to ensure that the gene is expressed properly and is stable over several generations of breeding.

A number of economically valuable characteristics have been introduced into plants by
genetic engineering. Most of the genetically modified crop plants used so far have transgenes that provide resistance to herbicides or insects. To improve crop production and soil management, research is now exploring how to increase the variety of transgenic characteristics to include resistance to drought, heat, cold, acid soils, and heavy metals.

Transgenic plants can provide food with enhanced nutritional content. For example, genetically modified “Golden Rice” contains two daffodil genes and one bacterial gene that together result in elevated levels of provitamin A.

These techniques could be applied to improve many characteristics in other crop species.

General info on GM foods

Genetically-modified food includes:

Advantages of this new agricultural technology reflect growth satisfaction with significant benefits ranging from:
1 more flexible crop management and rotation,
2 higher productivity and profits,
3 a safer environment through decreased usage of conventional pesticides and herbicides,
4 crops more insect and viral resistant,
5 crops more herbicide tolerant,
6 more desirable food products like delayed ripening tomatoes, oil seed rape with modified fatty acid, high oleic acid soybean, and carnations with extended shelf life and richer colour are produced, due to technology of genetic modification.

However, there are too, problems regarding production of GMOs. Those include:
1 worries about long term effect on human health, through the use of antibiotic resistant marker genes and the risks of allergen transfer,
2 influence of multinational seed companies on countries’ economies, and the possible demise of the small-scale farmers,
3 the increased use of pesticides and herbicides due to the resistance to pesticides of GM crops that would lead to reduced costs of control of weed, pest and disease infestation, the environment is greatly at risk of the chemicals.
4 growing reluctance to eat GM food by the general public, whether due to religious, ethical, health or environmental problems.

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We have done the HLFA. My part to do is,

Sources of GM foods

-Are they from animals or plants?
-What are the sources?
-What ingredients are commonly used in GM foods?