Xenobiochemistry

Xenobiochemistry is the study of biochemistry in extraterrestrial life. Like terrestrial biochemistry, xenobiochemistry can be divided into three fields: structural xenobiology, xenoenzymology, and xenometabolism.

As there is more than one alien biosphere, this article will cover only the basics as they apply to all discovered biochemistries at the moment.

History
Xenobiochemistry was a purely hypothetical field, originally under the umbrella field astrobiology. However, upon the discovery of an alien species, the field rapidly expanded and developed into a separate natural science.

Starting Materials
While a few alien species are almost certainly carbon-based, there appears to be a mixture of other starting materials for most of xenobiology. Below are listed some examples of different starting materials.

Alien1
On Alien1 Homeworld, biochemistry is silicon-based. Since most of the biochemistry is built around silicones, the common elements are silicon, oxygen, hydrogen, nitrogen, phosphorus, sulfur, and aluminum.

Xenobiomolecules
In terrestrial biochemistry, biomolecules are divided into one of four classes: carbohydrates, lipids, proteins, and nucleic acids. While the chemistry frequently deviates from these exact molecules in xenobiochemistry, there are still analogous structures present in every discovered biosphere. Below are some examples.

Carbohydrates
Carbohydrates are a type of compound used in terrestrial biochemistry for two purposes: storing energy and providing structure.

Alien1
Main Article: Silanols

In the case of Alien1 biochemistry, the structural component is satisfied by silanols, one of the few silicone-based structures that can form rings.

However, for energy storage, silicon nanocrystals act as semiconductors, storing the energy in extra electrons.

Lipids
Lipids are a type of compound used in terrestrial biochemistry used for a number of purposes, including cell structure, energy storage, and signaling.

Alien1
Main Article: Silicolipids

In Alien1 biochemistry, silicones fulfill the role of most fatty lipids, while the steroids follow suit, but vary significantly in structure.

Proteins
Proteins are macro-biomolecules in terrestrial biochemistry made from monomers called amino acids. Proteins are used for structural and functional roles.

Alien1
Main Articles: Deuteins and Phospho Acids

In Alien1 biochemistry, the equivalent to an amino acid is a phospho acid, which is a silicone-phosphate monomer that has the side groups on the phosphate end. These have a similar flexibility to the terrestrial amino acids, but are slightly larger than amino acids.

Nucleic Acids
Nucleic acids are a type of biopolymers that convey genetic information to all life. In terrestrial biochemistry, this role is filled by deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).

Alien1
Main Article: SNA

In Alien1 biochemistry, siliconucleic acids (SNA) store genetic information. SNA is more stable than DNA or RNA, but also forms a triple helix.

Metabolism
In terrestrial biochemistry, metabolism is maintained using glucose or other polysaccharides. Below, other methods of metabolism observed in alien life are described. If the energy source is the alternative to carbohydrates, the method will not be described below. Instead, see the correlating article on that xenobiochemistry.

Silicon Nanocrystals As Energy Source
Main Article: Alien1 Metabolism

As mentioned above, in Alien1 biochemistry, silicon nanocrystals are used to store energy.