Fluid Mosaic Membrane Model

There are three main substances within the cell membrane which are:

• phospholipids
• proteins
• carbohydrates

Chloesterol is within the membrane to improve fluidity

Channel proteins- allow the transport of water soluble molecules/substances

Carrier proteins- allow the active transport of ions (Na+ etc.)

Lipid soluble substances/molecules can diffuse through the membrane.

It is freely permiable to: non-polar molecules

Partially permiable to: polar molecules

Impermiable to: macro-molecules

These porcesses do not require ATP

Down the concentration gradient:

• Diffusion
• Facilitated diffusion

Down the water potential gradient:

• Osmosis

These mechanisms require ATP

Up the concentration gradient:

• Active transport

Bulk transport:

• Endocytosis
• Exocytosis