Lipid Bilayer Flashcards
What feature of lipids enables them to form a bilayer?
Amphipathic - hydrophilic head and hydrophobic tail
Why can hydrophilic molecules dissolve in water?
Polar. Contain charged or uncharged groups that can form electrostatic interactions or H bonds with water
Why are hydrophobic molecules insoluble in water?
Most of their atoms are uncharged and non polar so cannot form energetically favourable interactions with water
Why do hydrophobic molecules cluster together?
Hydrophobic molecules force the adjacent water molecules to reorganise. If the hydrophobic molecules cluster together, a smaller number of water molecules is affected - lower free energy cost
What does the bilayer mainly consist of?
Double layer of lipids consisting largely of phospholipids
What is a phospholipid made up of?
- Hydrophilic phosphate head
2. Two hydrophobic fatty acid tails
Why does a bilayer make a good barrier?
Water and other polar/charged substances cannot easily cross the hydrophobic core of the membrane
How are fatty acids named?
XX:Y n-y
- XX is the number of carbons in the chain
- Y is the number of double bonds counted from the methyl end
- n-y is the position of the first double bonded carbon
What does the number of double bonds indicate?
The level of chain saturation
C18:3
18 carbons and 3 points of saturation
What is the feature of saturated fatty acids?
Have no double bonds (saturated with hydrogens) and so are relatively straight
What is the feature of unsaturated fatty acids?
Contain one or more double bonds, often resulting in a bend/kink
What affects the shape of the lipid and spontaneous curvature of the membrane?
The relative size of the head group and hydrophobic tails of lipids
What lipids do bacterial membranes contain?
PG lipids and cardiolipins
Where are PG lipids and cardiolipins found in eukaryotes?
Mitochondria
