Biological molecules- lipids Flashcards
What is a lipid
A macromolecule containing hydrogen , carbon and oxygen
Why are lipids insoluble in water
They are non-polar and hydrophobic
State the 3 main groups of lipid
triglyceride, phospholipid, steriod
what are triglycerides composed of
1 glycerol molecule and 3 fatty acids
Why are lipids not considered a polymer
They are not contain monomers and therefore do not have repeating units
state the composition of a fatty acid
They contain a methyl group at one end and a carboxyl group at the other end of a hydrocarbon chain
Give 2 ways in which a fatty acid can vary from itself
1) length of the hydrocarbon chain
2) its saturation
what is the difference between a saturated and an unsaturated fatty acid
UNsaturated fatty acids contain at-least one DOUBLE carbon bond and saturated dont
If H atoms are on the same side of the C=C bond, they are….
Cis-fatty acids and CAN be metabolised by enzymes
If H atoms are on opposite sides on the C=C bond, they are…
Trans- fatty acids
What cant trans-fatty acids form?
Enzyme-substrate complexes, and therefore cant be metabolised
Why are unsaturated fatty acids more fluid than saturated fatty acids?
They have a lower melting point
State the difference between Mono and Poly unsaturated fatty acids
Monounsaturated have only 1 C=C bond where Polyunsaturated have more than 1 C=C bond
What are phospholipids composed of
2 fatty acids, a glycerol molecule and a Phosphate group
how do phospholipids form a bilayer
Hydrophobic tails orientate away from the water (intracellular) and hydrophylic heads orientate towards the water (extracellular)
