Transport across membranes

Made up of phosphate head and fatty acid tail

provide strength and are hydrophobic so help prevent water loss by limiting the movement of phosoplipids and fatty acids

carrier and channel

phospholipids can move in membranes, and it’s made from different molecules

water hating

water loving

Protein in the membrane with a carbohydrate chain attached that act as mechanical support and cell receptors

carbohydrate covalently bonded to a lipid which acts as a cell surface receptor for specific chemicals

water soluble Ions

Larger molecules/ ions

In a bilayer

The net movement of molecules or ions from a region where they are more highly concentrated to one where their concentration is lower until they are evenly distributed.

outside the cell

small, uncharged, lipid soluble molecules

Diffusion involving the presence of protein carrier and channel molecules to allow the passive movement of charged and larger molecules across plasma membranes

water filled hydrophilic channels across the membrane which only open to allow specific ions across.

when a specific molecule eg glucose binds and conformational change occurs which releases the molecule to the other side of the membrane

the tendency for water molecules to move (kilopascals)

Passage of water from a region where it has a higher water potential to a region where it has a lower water potential through a selectively permeable membrane

Osmosis stops when both sides of the membrane have equal water potential

Passive

When the water potential is higher, and the net movement of molecules enters the cell causing it to swell and burst

When the water potential is equal and the net movement of molecules neither enters nor exits the cell so there is no change.

the water potential is lower so the net movement of molecules leaves the cell so the cell shrivels