LOS ANGELES DNA and RNA molecules are the basis for all life on Earth, but they dont necessarily have to be the basis for all life everywhere, scientists have shown.

Researchers at the Medical Research Council in Cambridge, England, demonstrated that six synthetic molecules that are similar to but not exactly like DNA and RNA have the potential to exhibit hallmarks of life such as storing genetic information, passing it along and undergoing evolution. The man-made molecules are called XNAs.

DNA and RNA arent the only answers, said Vitor Pinheiro, the postdoctoral researcher who led the study, which was published this week in the journal Science.

Manipulating XNAs to behave like DNA and RNA could help scientists design better drugs, Pinheiro said.

It could also shed light on how life emerged on Earth, and on what living things might look like if they exist beyond our planet.

Everyone wants to know what aliens would use for DNA, said Steven Benner, a biochemist at the Foundation for Applied Molecular Evolution in Gainesville, Fla., who has synthesized artificial DNA but was not involved in the new study. Lab experiments tell you about the possibilities in the universe.

In natural life on Earth, the nucleic acids DNA and RNA are formed by sugar molecules deoxyribose in DNA and ribose in RNA that link to phosphates to form a backbone onto which the four nucleotide bases attach to form a chain.

Genetic information is stored in the order in which the bases known by the chemical letters A, C, G and T are strung along the chain.

DNA forms the template that holds all the information needed to create an organism. RNA takes that information and translates it into proteins, the basic building blocks of biology. (Viruses, which some scientists consider to be a life form, use only RNA.)

To build alternatives to DNA and RNA, scientists often fiddle with one component or another and see how the changes affect genetic function.

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Researchers make alternatives to DNA and RNA