Lipids Flashcards
Which elements do lipids contain?
Carbon, Hydrogen and Oxygen (proportion of oxygen is low; much lower than in carbohydrates)
What does a fatty acid look like?
It has an acid (COOH) group at one end, and then the rest of the molecule is a hydrocarbon chain (a chain containing only carbon and hydrogen, most commonly around 18 carbons long)
What is a saturated fatty acid?
Fatty acids with no carbon-carbon double bonds in the hydrocarbon chain, so the maximum number of bonds with hydrogen atoms have been made.
What is an unsaturated fatty acid?
Fatty acids with at least one carbon-carbon double bond in the hydrocarbon chain.
What does a triglyceride consist of?
One glycerol molecule bound to three fatty acid molecules.
In a triglyceride, what kind of bonds join the three fatty acid molecules to the glycerol molecule? What kind of reaction forms these bonds?
Ester bonds! Formed via condensation reactions of the acid groups on the fatty acids and OH groups on the glycerol (a water molecule is lost).
Are triglycerides hydrophobic or hydrophilic?
Hydrophobic (insoluble in water).
What is a phospholipid, and where are they found?
It is almost identical to a triglyceride molecule, but instead of three fatty acid molecules joined to a glycerol, there are two fatty acid molecules and one phosphate bound to a glycerol molecule.
Which part of a phospholipid is hydrophilic, and so faces outwards in teh lipid bilayer?
The phospholipid head.
To break down (respire) lipids, what kind of bonds must be broken, and what kind of reaction is this?
Ester bonds - to break these is a hydrolysis reaction (involves the addition of a molecule of water). This breakdown releases energy, which is used to generate ATP.
Lipids are insoluble in water. Why is this a good thing for an energy store?
It means that they can be stored in a compact way, and means that they don’t affect the water potential of the cell contents.
Cholesterol is a class of lipid. It’s a small molecule made of 4 carbon-based rings. What is it useful for?
In cell membranes, it is small so can sit in between phospholipid hydrocarbon tails. It helps to regulate fluidity and strengthen the cell membrane.
