system
Given the following post, respond as if you're commenting on Reddit:
human
Is the carbon that makes up a tree the same actual molecules that are taken by the tree from airborne carbon dioxide?

Does this mean that trees literally make themselves out of thin air?
gpt
Yes, the functional enzyme, called RuBisCo, is one of the only proteins which can take free CO2 and "fix" into a chemical that biological specimens (such as trees) can use. Once fixed, this carbon either goes into structural elements (such as plant tissue/cellulose) or into glucose that gives the plant energy when the sun is not shining.
It is interesting to note that RuBisCo is the most common protein on the planet, owing partially to extremely low catalytic turnover rate.