Biological molecules (lipids) Flashcards
What is a triglyceride
a lipid made up of 3 fatty acids and one glycerol
how are triglycerides formed
an ester bond caused by OH groups interacting between the glycerol and fatty acids
why are lipids insoluble
on the fatty acid the ‘r’ group is hydrophobic meaning it doesn’t interact.
is an ester bond an example of a condensation reaction?
yes
what is the difference between saturated and unsaturated lipids
saturated fats have all the bonds taken up whereas unsaturated have one or more unsaturated bonds
how does being saturated or unsaturated affect the structure
having a double bond means there is a change of structure as the fatty acid has a kink in it therefore it cannot pack as compactly and turns into oils instead of fats.
what is the difference between triglycerides and phospholipids
they have 2 fatty acid tails and instead of a third they have a phosphate group attached
how do phosphate molecules change the lipid
the phosphate is negatively charged meaning it causes the water to interact making it very hydrophilic compared to the hydrophobic areas resulting in a bilayer to prevent the hydrophobic tails being exposed to water
what are sterols
complex alcohol molecules which are hydrophilic and hydrophobic
what is cholesterol useful for
stability of the cell membrane
what are triglycerides used for
they are a effective energy storage molecules as they have a high proportion of carbon to carbon bonds meaning they release double the amount of energy compared to carbs. They are insoluble meaning they don’t increase the osmotic pressure either meaning they can be easily stored without causing the cell to swell up.
what are phospholipids used for
they control what enters and leaves the cell, due to the hydrophilic/hydrophobic regions they create a double layer. The hydrophobic centre stops water soluble substances getting in
