B1.1.12 — Formation of phospholipid bilayers as a consequence of the hydrophobic and hydrophilic regions

Cell membrane

Phospholipids form the basic structure of the cell membrane.

There several transport mediating proteins embedded in these phosphoplipids

How are phospholipids membrane formed

Membranes are formed when a hydrophilic phosphate head bonding with two hydrophobic hydrocarbon (fatty acid) tails

• As phospholipids have a hydrophobic and a

  hydrophilic region

Amphipathic

The phosphate head of a phospholipid is

polar, so is hydrophilic and therefore soluble in water

The fatty acid tail of a phospholipid is nonpolar so is hydrophobic and therefore insoluble in water

Molecules with both polar/hydrophilic and non polar/hydrophobic regions are

said to be amphipathic

Phospholipid bilayer and monolayer formation

When placed in water, the hydrophilic phosphate heads orient themselves towards the water and hydrophobic hydrocarbon tails orient themselves away from the water, causing them to form phospholipid monolayer

Such layers later combine to form phospholipid bilyaers- form basic structure of cell membrane

Amphipathic and barrier

Amphipathic nature natyre of phospholipids means that phospholipid bilayer acts as a barrier to most watrer-soluble substances

Non polar fatty acid tails

Prevents polar molecules or ions from passsing between them across the membrane .

means that water soluble molecules like sugars, amino cids and proteins cant leak out of the cells and unwanted water soluble molecules cant get in

phospholipid bilayer diagram