Genetic Engineering Essay

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1.6.1 Genetic engineering
Genetic engineering depends on the location and analysis of genes on chromosomes and ultimately DNA sequencing. The early cartography of the genes used the principles of Mendelian genetics . It is assumed that alleles that are transmitted together side by side are located on the same chromosome : it is said that are connected or linkage . These genes form a bridging group - linkage group : are the same for gametes and are usually transmitted together , so they do not have independent distribution. Crossing-over occurring during meiosis may cause these alleles can be exchanged between the chromosomes of a homologous pair .

By analyzing the frequency of crossovers for many different alleles can trace a linear map of each chromosome.

Modern techniques , rather than the gene map , maps the map of the DNA within the gene itself : the positions of short sequences " marker " are used as markers signaling over the cromosssomas . Once a gene is discovered, it is necessary to unravel its base sequence prior to its function being studied . The sequencing has become easier with the development of methods for cloning the DNA - producing large amounts of identical fragments. In the method most widely used DNA sequencing , the chain is denatured into single strands . These are then used as templates for DNA synthesis , but such that replication to as the double helix reaches a certain growth in the mold base . In addition to provide DNA polymerase and the four bases, A - G -C- T, also using small amounts of these dideoxynucleotide bases. This is incorporated , as the normal bases, the double helix growth but prevent the continuation of the chain. The fragments are then separated by gel electrophoresis and the base seq...

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... for genetic diagnosis .

Forensic genetics has other applications . The " fingerprint " DNA represents a valuable tool for forensic science . As is the case with an ordinary fingerprint genetic fingerprint is unique to each individual (except identical twins ) . The determination involves the observation of specific DNA sequences which can be obtained from extremely small tissue samples , hair, blood or eventually left at the scene . As Fifty microliters of blood, semen or five microliters of ten roots of hairs are enough , and nozzles secretions and cells from the fetus . In addition to its use in the capture of criminals , especially rapists , the genetic fingerprints can be used to establish family relationships . People involved in the conservation of species use them to be sure that captive breeding is among individuals who do not belong to the same family .

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