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)
Why are phospholipids amphythatic?
They have both hydrophobic and hydrophylic parts (polar and non-polar)
State one property of the phospholipid bilayer
it is selectively permeable, only small non-polar molecules can move through
How does an ester bond form?
When a Hydroxyl group bonds with a Carboxyl group
What type of reaction is the formation of an ester bond
A condensation reaction
what is the function of a phospholipids
cell membrane component
what is the function of a triglyceride
energy storage
state one example of a hydrolysis reaction
digestion
What is the composition of a cholesterol molecule
4 carbon-based rings and a hydrocarbon tail
By fitting inbetween phospholipids, what does cholesterol do to the cell surface membrane
Regulates its fluidity and permeablity
How does cholesterol make the
