Fuel
We need fat. From bacteria and yeast to petunias, goldfish and humans, every single action an organism performs, whether conscious or not, requires some sort of fuel. Budding, photosynthesis, predation, digestion, hibernation, seeing, thinking, eating, breathing, immunity, sleeping, swimming, walking - the list is far too long to draw. Not everything works on fat, of course. Sugars and adenosine triphosphate (ATP) are also extensively used. It all depends on the metabolism and the biochemistry involved. The fact is, organisms are in constant need of energy, which is why they store it continuously. Triacyglyerol (TAG) is the main form of fat stored by animals and plants, and adipocytes are specifically dedicated to its accumulation. Within adipocytes, as is the case for most eukaryotic cells, TAG is confined to intracellular specialised bodies known as lipid droplets (LDs). Though ignored for years, more and more attention is being given to LDs. Once considered mere globs of fat, LDs have now been promoted to the status of full-blown organelles with their own dynamics. Lately, scientists discovered a protein intricately involved in their genesis and growth. They called it adipogenin.
