Most one‑carbon transfers are promoted by one of three cofactors: biotin, tetrahydrofolate, or S‑adenosylmethionine. S‑Adenosylmethionine is generally used as a methyl group donor; the transfer potential of the methyl group in N5 ‑methyltetrahydrofolate is insufficient for most biosynthetic reactions. However, one example of the use of N5 ‑methyltetrahydrofolate in methyl group transfer is in methionine formation by the methionine synthase reaction; methionine is the immediate precursor of S‑adenosylmethionine. List the three methyl donors in order of methyl group transfer potential highest to lowest.

it can be observed without changing the identity of the object.

it depends on what substance you're talking about as well as many other factors. in quantum mechanics, the observation of particles affects the observers ability to measure certain properties. for example: you can know the velocity of a particle, but you can't know it's position; or you can know it's position, but not it's velocity. it's like trying to find out where a grain of sand is by throwing other grains of sand at it. once you find out where it is, it's been moved. it's also like trying to find an answer to the question of whether or not a tree falling in a forest makes a sound if nobody is there to hear it. paradoxically, the only way to find out is to be there and hear it.