Lipids-phospholipids Flashcards
How are phospholipids formed
A condensation reaction between the two -COOH of the fatty acid tails and the two -OH groups of the glycerol.One of the -OH groups on the glycerol reacts with a phosphoric acid molecule.Three molecules of water are produced and three ester bonds are formed(Draw a diagram).
What’s the common number of carbons in the fatty acids found in phospholipids
16 or 18
Is one fatty acid tail saturated in phospholipids and one unsaturated
Most commonly this is the situation
How do phospholipids behave in water
When surrounded by water, the P group has a - charge, making it polar.But the fatty acid tails are non-polar. The ‘head’ is hydrophilic and the ‘tail’ as hydrophobic, so the phospholipid molecule is amphipathic. They form a layer on the surface of the water with heads in the water and tails sticking up out of the water(draw a diagram).
Can phospholipids form micelles
They can also form micelles(draw a diagram)
How do phospholipids form a bilayer
Inside and outside a cell membrane is an aqueous solution. The phospholipids form a bilayer, with two rows of phospholipids, tails pointing inwards and heads pointing outwards into solution. Between 20-80% of membranes in plant and animal cells are made of phospholipids. Bacterial membranes tend to contain a greater proportion of protein.
What gives the membrane some stability
The individual phospholipids are free to move around in their layer, but will not move into any position where their hydrophobic tails are exposed to water.
Describe the permeability of the phospholipid bilayer
The membrane is selectively permeable. Only small and non-polar molecules to move through the tails in the bilayer, such as oxygen and carbon dioxide. This lets the membrane control what goes in and out of the cell, and keeps it functioning properly.
Draw a diagram of the phospholipid bilayer
