Cell membrane and transport mechanisms
VBS Home page,VBS Course Navigator, Cells,Cell Membrane and transport mechanisms.,Previous Page, Next Page, top of page
Remember that all material that the cell gets from the environment or
sends to the environment has to go through the cell or plasma membrane.
The membrane is basically a phospholipid bi-layer with various proteins
embedded into it. What's key to realize is that the cell membrane is semi
permeable, that is some materials can get through the membrane while others
|Chemicals that can pass through the membrane||Chemicals that cannot pass through the membrane|
|Passive transport mechanisms||Active Transport mechanisms|
The passive transport mechanisms and the protein pump mechanisms involve movement of substances as single molecules across the membrane. The "bulk" flow mechanisms endocytosis and exocytosis enable the cell to take in very large packages of molecules...say a food item from the environment. Many books treat these bulk flow mechanisms as seperate from active transport for that reason.