Question

1. The solubility of fat in water depends on pH, especially at relatively high temperatures. For example, at pH 3 and 60 degrees Celsius, the solubility of a Palmitic Acid is only 5 micromole per liter, whereas at pH 7 and the same temperature it is 1 milimole per liter. Explain the dependence of the solubility of fatty acids on pH.
2. What is the link between the amount of carbons on the hydrocarbon chain of a fatty acid and its solubility in water? Explain.
3. In what respects do structural lipids and storage lipids differ?

Answer 1

Ans a

pH-dependent solubility of fat

At acidic pH since there are more number of hydronium ion hence the fatty acid is weakly ionized due to the presence of common ion. (i.e. Fatty acid on dissociation will also produce hydronium ions) which is not in case of neutral pH. Hence palmitic acid displays more solubility in neutral pH than acidic at a given temperature.

And b

The chain length increases, the solubility of the fatty acids in water decreases. This is due to fact it tends to reduce the surface area by coagulating due to an increase in hydrophobicity.

Ans c

the lipids are classified into two types based on their functions

1. Structural lipids are responsible for the structural organization of body.

a. Phospholipids: The fatty acid content L-glycerol phosphate.

b. Glycerophospholipid: Phosphatidylcholine, Phosphatidylserine

c. Sphingolipid: sphingomyelins, glycosphingolipid

d. Cholesterol

2. Storage lipids: They includes fat oil nad waxes responsible for storage of energy.