Biochemistry

Biochemistry involves the chemical makeup and molecules of an organism. Though carbon is the most suitable of elements to be the basis of an organism's biochemistry, other elements can be substituted.

Carbon
The majority of life in the universe is carbon-based, because carbon has four valence electrons - it is capable of bonding to four other atoms, and its stability to hold these atoms together allows it to form a wide variety of complex molecules. The most commonly bonded elements are oxygen, nitrogen and hydrogen. Other elements found in carbon-based life forms include phosphorous and sulfur.

Carbon based life will form four basic macromolecules which are used to carry out life processes. Proteins which form the structures of living organisms, nucleic acids which contain genetic information, carbohydrates which store energy used by living cells, and lipids which store energy for more extended periods than carbohydrates.

Silicon
Silicon, like carbon, also four valence electrons and can form a variety of molecules as well. Instead of long chains, it will form a crystal lattice, resulting silicon-based life appearing as crystals. Silicon-based life lacks the agility of carbon-based life as a result. Silicon-based life will feed on on electromagnetic radiation and communicate with one another via harmonic resonance. As a result, they are not likely to have the same sensory organs found in carbon based life.

Germanium
Germanium also contains four valence electrons. Just as silicon based life appears crystalline, germanium-based life appears to be made of rock. Germanium herbivores will likely feed on rocks and minerals.