The very function, or job of CELL MEMBRANES is to protect the cell from it's surroundings, or in other words, to keep it safe. It controls the movement of substances in and out of cells and organelles, like a guard watching for suspicious activity and protecting something.
The cell membrane itself is a thin, flexible layer around the cells of all living things. It separates the inside of the cells from the outside of the cells.
The reason scientists believe this is that there was basically no oxygen in the atmosphere at this time, which meant that cells needed to be anaerobic to survive,<span> going around the problem of no oxygen in the atmosphere.
Hope this helps.</span>
Mitochondria play a critical role in the generation of metabolic energy in eukaryotic cells.
