Your cells have a post office
All plant, animal and fungal cells contain a number of different “organs,” known as organelles, which carry out various tasks within the cell. The energy-producing mitochondria and the DNA-containing nucleus are examples of such organelles. The components these organelles need to perform their tasks are usually produced outside of the organelles, so to make sure each organelle gets what it needs, the cells also have a “post office”: the Golgi apparatus, which packages and labels the components and then sends them off using its tiny cellular couriers.
Sharks are older than trees
What is life?
As you might or might not know, viruses are very simple
entities, consisting of nothing more than a shell that contains
the genetic material and handful of proteins required to hijack
the replication machinery of cells. Viruses are, in fact, so
simple that they do not even meet the standard definition of
life, as they cannot grow, regulate their internal environment
or (independently) metabolize. Yet, they are not the gold
medalists of simplicity—that position is taken by
the viroid, an infectious entity that consists of
nothing but genetic material. No shell, no proteins, no
nothing. Just a strand of RNA1
casually hijacking a cell.
(You, by contrast, consist of trillions of cells, each of
which depends on tens of thousands of different proteins2
to perform the processes that are keeping you alive.)
1 RNA is like DNA, but with an R.
2
As in unique kinds of proteins—If we’re counting total, we’re
up in the billions.