Genetics Essay Research Paper GENETIC ENGINEERING

Genetics Essay, Research Paper

GENETIC ENGINEERING

“career of the future”

Genetic engineering is an umbrella term that can cover a wide range of ways of

changing the genetic material — the DNA code — in a living organism. This code contains

all the information, stored in a long chain chemical molecule, which determines the

nature of the organism. Apart from identical twins, genetic make-up is unique to each

individual. Individual genes are particular sections of this chain, spaced out along it,

which determine the characteristics and functions of our body. Defects of individual

genes can cause a malfunction in the metabolism of the body, and are the roots of many

.genetic. diseases.

In a sense, man has been using genetic engineering for thousands of years. We

weren’t changing DNA molecules directly, but we were guiding the selection of genes.

For example the domestication of plants and animals.

Recombinant DNA technology is the newest form of genetic engineering, which

involves the manipulation of DNA on the molecular level. This is a totally new process

based on the science of molecular biology, a relatively new science only forty years old.

It represents a major increase in our ability to improve life. But a negative aspect is that it

changes the forms of life we know of, possibly damaging our environment

It has been known for some time that genetic information can be transferred

between micro-organisms. This is process it done via plasmids (small circular rings of

DNA) or phages (bacterial viruses). Both of these are termed vectors, this is because of

their ability to move genetic material. In general this is limited to simpler species of

bacteria. nevertheless, this can restriction can be overcome with the use of genetic

engineering because it allows the introduction of any gene.

While genetic engineering is beginning to be used to produce enzymes, the

technology itself also depends on the harnessing of enzymes, which are available in

nature. In the early 1970s Herbert Boyer, working at the University of California Health

Science Centre in San Francisco, and Stanley Cohen at Stanford University found that it

was possible to insert into bacteria genes they had removed from other bacteria. First

they learned the trick of breaking down the DNA of a donor organism into manageable

fragments. Second, they discovered how to place such genes into a vector, which they

used to ferry the fragments of DNA into recipient bacteria. Once inside its new host, a

transported gene divided as the cell divided, leading to a clone of cells, each containing

exact copies of the gene. This technique became known as gene cloning, and was

followed by the selection of recipient cells containing the desired gene.

The enzymes used for cleaving out the DNA pieces act in a highly specific way.

Genes can, therefore, be removed and transferred from one organism to another with

extraordinary precision. Such manoeuvres contrast sharply with the much less predictable

gene transfers that occur in nature. By mobilising pieces of DNA in this way (including

copies of human genes), genetic engineers are now fabricating genetically modified

microbes for a wide range of applications in industry, medicine and agriculture.

The underlying idea of transferring genes between cells is quickly explained.

However the actual practice is an extremely complicated process. The scale of the

problem can be gauged from the astronomical numbers involved: the DNA of even the

simplest bacterium contains 4,800,00 pairs of bases. But there is only one copy of each

gene in each cell.

First, restriction enzymes are used to snip the DNA into smaller pieces, each

containing one or just a few genes. These enzymes cut DNA in very precise ways. They

recognise particular stretches of bases (termed recognition sequences) and snip each

strand of the double helix at a particular place. Whenever the recognition sequence

appears in the long DNA chain, the enzyme makes a cut. Whenever the same enzymes

are used to break up a certain piece of DNA, they always produce the same set of

fragments. The cuts produce pieces of double helix with short stretches of single

stranded DNA at each end. These are know as sticky ends. If the enzyme is allowed to act

for a limited time, it may not have a chance to attack all the recognition sequences in the

chain. This will result in longer fragments.

As in natural DNA replication, bases have an inherent propensity to join up with

their partners A with T, for example, and G with C. So too with sticky ends. For

example, the sequence TTAA will tend to re-associate with AATT. Genetic

engineers use another type of enzyme, DNA ligase, to make the union permanent. This is

the key principle of genetic engineering the use of two types of enzyme to cut out one

piece of DNA and then to attach it to another piece. The genetic engineer’s t

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