Gene duplication#Gene duplication as amplification

Under amplification is meant in genetics the specific amplification of DNA segments. Amplification plays as a method in molecular genetics an important role, but is also of course take place in cells. The reproduction of the whole genome ( polyploidization ) is no amplification in the proper sense, since large quantities of DNA to be copied without relevance.

Amplification as a technique

The most significant technique of DNA amplification is the polymerase chain reaction, see also there.

Amplification in nature

The selective amplification of DNA is also a natural process. It is used to increase, if necessary, the activity of individual genes. It has on several creatures, such as when diving beetles ( Dytiscus marginalis ) or the clawed frog (Xenopus laevis) found that they can amplify extrachromosomal ribosomal DNA. This happens especially in oocytes, because there the demand for ribosomes is greatly increased. The amplification is performed by the rDNA is excised and circularized. The rDNA rings are then propagated through rolling circle replication and thus lack the same again.

Another example of the natural amplification of the genes provide for the egg membrane ( chorion ) in the follicular cells of Drosophila melanogaster. Before the genes is a unidirectional origin of replication ( ori). This causes only the genes are selectively replicated, while other genomic regions remain in the old number. The replication is where the genes at several times to make it look like an onion shell structure in the electron microscope, which is why it is also called onion skin replication. The Choriongene versechzehnfacht be there to provide enough protein for the rapid growth egg.

For amplification can occur "in response " by some oncogenes against cytostatics. In the therapy of cancer, are often used as a cytostatic agent that prevent the production of the nucleobases or their precursors. The cancer cells are responding by amplification of those gene regions whose gene products are inhibited or blocked by the cytostatics. The amplification occurs by the formation of so-called intrachromosomally homogeneous staining regions, ie homogeneous chromosome or extrachromosomal extensions by so-called double minutes.

• Genetics