They carry the genes, the factors or units–‘blueprints’–that determine hereditary characteristics.
There is consciousness in everything. Visible or invisible to us, each fragment, of the universe has a consciousness of its own. Pain and pleasure, the strongest aspects of all consciousnesses, are experienced by every fragment, according to its degree. Differentiation is of course various, and it is in the degree of differentiation that consciousnesses are different.
Reincarnation simply represents probabilities in a time context.