The following nine points will highlight the nine important mechanisms involved in the movement of materials through cell membranes.
1. Physical Process:
Molecules are transported without the membrane and there is no expense of metabolic energy.
Net movement of molecules (or ions) from a region of greater concentration to a region of lower concentration of concerned molecules.
3. Facilitated Diffusion:
Carrier protein in cell membrane accelerates movement of relatively large molecules from region of their higher to region of their lower concentration
Water molecules diffuse from region of their higher to region to their lower concentration through semipermeable membrane.
5. Physiological Process:
Molecules are transported across the membrane against concentration gradient at the expense of metabolic energy (ATP).
6. Active transport (pump):
Protein molecules in cell membranes transport ions or molecules through membrane; movement may be against concentration gradient (i.e., from region of lower to region of higher concentration of concerned molecules, and is supported by ATPase activity).
Cell membrane encircles particle and brings it into cell by forming a vacuole around it.
Cell membrane takes in fluid droplets by forming vesicles around them.
Cell membrane ejects materials; vesicle filled with material fuses with cell membrane. It is cell vomiting process.