Lipids

Question 1

Lipids

Answer 1

• contains carbon, hydrogen and oxygen
• non-polar compounds
• insoluble in water
• can dissolve in organic solvents, e.g. alcohols

Question 2

Properties of lipids (single C-C bond)

Answer 2

• the differences in the properties of fats come from the variations in the fatty acids
• if the hydrocarbon chain has only single C-C bonds, the fatty acid is saturated
• all the carbons atoms are linked to the maximum possible number of hydrogen atoms
• they are saturated with hydrogen
  atoms
• the fatty acid chain is a straight zig-zag
• the molecules can align readily, so fats are solid
• they remain semi-solid at body temperature
• useful for storage in mammals
  - animal lipids often contain saturated fatty acids

Question 3

Properties of lipids (double C-C bonds)

Answer 3

• if any C-C bonds are not single, the molecule is unsaturated, and the chain gest a kink.
• the molecules cannot align uniformly
• the lipids cannot solidify readily
  - why unsaturated lipids are oils, which remain liquid at room temperature.
  - plant lipids are often unsaturated and occur as oils
• if one double C-C bond is present, the molecule is mono-unsaturated
• if there are many double C-C bonds, the molecule is called a polyunsaturated.

Question 4

Waxes

Answer 4

• waterproofing
  - in terrestrial organisms
  - reduce water loss, e.g. in the insects exoskeleton