Transport of molecules within a cell and out of the cell requires a complex endomembrane system. Endocytosis occurs when the cell membrane engulfs particles (dark blue) outside the cell, draws the ...

This takes place when molecules diffuse across the cell membrane by travelling through specific transport proteins. It occurs down a concentration gradient - molecules move from an area of high to ...

Membrane proteins are proteins found in cell membranes, either at the surface or on intracellular organelles. Integral membrane proteins such as receptors and ion channels span the membrane.