Xenobiology

Xenobiology (XB) is a subfield of synthetic biology, the study of synthesizing and manipulating biological devices and systems. Xenobiology derives from the term xenos, which means "stranger, guest". Xenobiology describes a form of biology that is not (yet) familiar to science and is not found in nature. In practice it describes novel biological systems and biochemistries that differ from the canonical DNA-RNA-20 amino acid system (see the classical central dogma in molecular biology). For example, instead of DNA or RNA, XB explores nucleic acid analogues, termed Xeno Nucleic Acid (XNA) as information carriers. It also focuses on an expanded genetic code and the incorporation of non-proteinogenic amino acids into proteins.

Difference between xeno-, exo-, and astro-biology

Astro means star and exo means outside. Both exo- and astrobiology deal with the search for naturally evolved life in the Universe, mostly on other planets in Goldilocks zones. Whereas astrobiologists are concerned with the detection and analysis of (hypothetically) existing life elsewhere in the Universe, xenobiology attempts to design forms of life with a different biochemistry or different genetic code than on planet Earth.