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How to produce an insect resistant tomato plant?

What are genes, and where are they found?
There are genes in everything that lives, or has lived. There are genes in people, flies, ham, tomatoes, bacteria etc. A 200g steak contains 750,000,000,000,000 genes.

A gene is a code that governs how we appear and what characteristics we have. There are, for example, genes which decide whether we have blue or brown eyes. We receive half of our genes from our mother, the other half from our father.

Plants have genes too. Genes decide the colour of flowers, and how tall a plant can grow. Like people, the characteristics of a plant will be transferred to its children- the plant seeds, which grow into new plants.

What is genetic modification?
Genetic modification changes the genes and thereby the characteristics of the subject. You can, for example, genetically modify strawberries so that they stay fresh for longer, and rice can be genetically modified so that it has a higher vitamin content.

When a scientist genetically modifies a plant, they insert a foreign gene in the plant's own genes. This might be a gene from a bacterium resistant to pesticide, for example. The result is that the plant receives the characteristics held within the genetic code. Consequently, the genetically modified plant also becomes able to withstand pesticides.

With genetic modification it is possible to transfer genes from one species to another. This is because all genes, be they human, plant, animal or bacterial are created from the same material. Genetic scientists therefore have a huge amount of genetic characteristics to choose from.

How does a genetic scientist work?
Genetic modification of plants occurs in several stages:

1. The scientist finds and isolates the gene with the desired genetic characteristics. This process is called mapping.
2. The scientist makes several copies of the isolated gene. The copying process is called PCR.
3. The scientist transfers the desired genes to the plant's own genes (using a piece of plant tissue). When the scientist wishes to insert the desired genes into the plant - there are 3 options. He or she can use a 'gene canon', a soil bacteria or a material called protoplast. The methods of gene insertion are called 'transformation'.
4. The scientist creates a new plant from the genetically modified plant tissue.
5. The scientist checks that the inserted genes function as expected.
6. The scientist also checks that the inserted gene appears in the plant's progeny, that is - in the seeds.

How do we know if the genetic modification has succeeded?
Only rarely can one see whether a plant or animal has been genetically modified, with the naked eye. Scientists have therefore developed some techniques to assist them.

For example - a special colour test can identify whether a plant is genetically modified. At the time when the plant is genetically modified, the scientist inserts an extra marker gene into the plant. The marker gene can have different characteristics, for example, it can make the plant change colour when exposed to a chemical test.

In this way, scientists can identify whether the plant has been genetically modified or not by performing a chemical test and noting the colour of the plant.

What is the difference between genetic modification and traditional processing?
Long before the discovery of genetic modification, farmers have improved their crops by what we today call "traditional processing".

Processing is when one crosses the best, largest, most attractive or best tasting samples of a certain species with each other in order to get a plant or animal, that is even better, larger, more attractive or better tasting.

In traditional processing genes are transferred from one plant to another. This is also the case with genetic modification - however the way in which it is done is very different.

Genetic modification is a more precise technique, where one can be exact in transferring the desired characteristics. In traditional processing one cannot avoid the possibility that other characteristics may also be transferred.

In traditional processing, characteristics can only be exchanged between species which are the same or very similar. In genetic modification, characteristics can be transferred from one species to a quite different one, even between plants and animals.

Genetic modification is less time-consuming than traditional processing.

In what other ways can genes be altered?
Not only genetic modification can be used to change animal and plant genes.

Spontaneous changes, radiation, chemicals and traditional processing can also alter the characteristics of a plant or animal.

Spontaneous alteration of genes takes place naturally and sometimes with no effect. A spontaneous alteration can lead to the development of both positive and negative characteristics. The method is not particularly good if the intention is to create specific changes.

Radiation and chemicals can be used in order to effect gene alteration. Both elements are sometimes used in plant processing.

In traditional processing closely related plant or animals are crossed. It might be maize and navew or a horse and a donkey. In this way different combinations of genes occur in the progeny. Those with desirable characteristics are selected over several generations. The crops and livestock we see today are a result of traditional processing.

Can everything be genetically modified?
Yes. In principle anything that lives can be genetically modified - animals, people, plants and bacteria.

You can in other words transfer characteristics from a fish to a strawberry. But the less alike the species are, the more difficult it is. It is easiest to genetically modify related species.

Not all characteristics can be transferred. Some characteristics occur only by interaction between many genes. Only rarely do scientists have a good enough view of this interaction to be able to recreate it.

At the moment, scientists are working intensely on mapping genes in humans and pigs. Perhaps it will give them sufficient knowledge and vision so that in the future they can create even more complicated genetic modifications than today.

What is inheritance?
What is a gene?
What is a chromosome?
What is DNA?
What is a protein?
What is mitosis/meiosis?
Genetic testing for disease
How to clone a human embryo to cure disease?
How to get stem cells from an embryo?
PCR


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