are membranes and their proteins important? They:
- hold the cell together,
keeping its parts in place.
- are partially porous,
helping to keep water and its dissolved chemicals inside
the cell so they can do their work. Proteins in the
membrane create adjustable holes (pores) so
the cell can make adjustments in chemical composition
- as they do when generating electrical currents.
Proteins Do Two Things
- Send signals. These proteins provide a way for communication
between substances on the outside with target molecules
on the inside.
- Transport. Like trucks, these
proteins carry other molecules. They move
molecules from one side of the membrane to the other side,
even against a high concentration of similar molecules. This
is like breaking the "laws of
diffusion." Think of it like driving a truck up a steep
communicate with the physical and chemical world outside
the cell, and the world within the cell.
proteins transport other molecules.