Scientists might one day be able to add new words to your DNA’s vocabulary and give it important lifesaving instructions.

A team reported in the journal Nature that it gave two new base elements of genetic code to a group of microorganisms and got the creatures to use them. The researchers call it an “expanded genetic alphabet.”

Just as computers transmit information with long strings of 0s and 1s, DNA stores information with the special molecules adenine, cytosine, guanine, thymine and uracil, known in shorthand by their initials. In the DNA’s double helix, the structure of our genetic code, A pairs with T and C with G to form the rungs of its twisting ladder. That fifth letter, U, comes into play with cells’ RNA, which is like a copy of the body’s instruction manual that cells use as their guide — in the RNA, A actually pairs with U instead of T.

Together, the sequences of the pairs as they appear in a DNA strand translate to orders that the body uses to function. They tell the cells how to put together amino acids to build crucial proteins.

What these scientists did was add two new letters to DNA’s alphabet, X and Y, to expand it significantly. They designed E. coli bacteria that carried the additional genetic components and then used the instructions stored within them to build fluorescent proteins.

“The resulting semi-synthetic organism both encodes and retrieves increased information and should serve as a platform for the creation of new life forms and functions,” the scientists wrote in their study.

As Gizmodo points out, the scientists reported designing the two new letters and incorporating them into bacterial DNA a few years ago.

If the process is advanced and refined, one day scientists may be able to harness it to program life itself — creating living organisms that perform specific functions within your body or the larger ecosystem. So far, the bacteria’s new genetic instructions and tasks represent only a very basic usage of the technique.

“The reported [semi-synthetic organism] is likely to be just the first of a new form of semi-synthetic life that is able to access a broad range of forms and functions not available to natural organisms,” the study said.