BASIC RULES OF TRANSPORTATION IN CELLS

• A cell must regulate transport of substance across cellular boundaries 

PLASMA MEMBRANES AND TRANSPORTATION

• Selectively permeable regulating the cell’s molecular traffic 

HYDROPHOBIC MOLECULES IN TRANSPORTATION

• Hydrophobic molecules can dissolve in the lipid bi-layer or the membrane and cross it easily 

HYDROPHILIC MOLECULES IN TRANSPORTATION

• Hydrophilic molecules (polar) such as sugars, do not cross the membrane easily

TRANSPORT PROTEINS

• Allows passage of hydrophilic substances across the membrane

EXTENDING TRANSPORT PROTEINS

• Some transport proteins called channel proteins,have a hydrophilic channel that allows certain molecules to go through a tunnel 

CHANNEL PROTEINS

• Called Aquaportins, facilitate the passage of water

• Bind to molecules and change shape to shuttle them across the mmebrane