10. Lipids

Which fatty acid chain would you expect to be least soluble in water?

a) 16-Carbon fatty acid. 

b) 4-Carbon fatty acid.

c) 22-Carbon fatty acid.

d) 12-Carbon fatty acid.

What is the molecular formula of Linolenic acid, an 18-carbon polyunsaturated fatty acid with 3 double bonds?

a) C₁₈H₃₂O₂

b) C₁₈H₃₀O₂

c) C₂₈H₃₀O₂

d)C₁₈H₃₄O₂

What aspect of each of the 18-carbon fatty acids in the table below is correlated with their melting point?

a) The charge of the carboxylic acid group.

b) The length of the hydrocarbon chain

c) The number of double bonds

d)The polar hydrocarbon chains

What happens to the melting point in fatty acids as the hydrocarbon length increases?

a) It increases.  

b) It decreases.

c) It stays the same.

d) There is no direct correlation.

Unsaturated fatty acids: 

a) Usually contain a double bond with cis stereochemistry.

b) Are found in both plants and animals. 

c) Sometimes contain multiple double bonds. 

d) Have lower melting points than the analogous saturated fatty acids.

e) All of the above are correct.

Which of the following are correct with regard to saturated fatty acids?

a) They are generally solid at room temperature. 

b) The carbon backbone contains at least one double bond, creating a kink in the chain. 

c) Come primarily from vegetable products. 

d) They are only hydrocarbon chains, making them liquids at room temperature.

e) Cannot be present in other lipids, such as phospholipids.

Match each of the fatty acids with the appropriate melting point:

a) CH₃(CH₂)₁₈COOH ______

b) CH₃(CH₂)₁₄COOH ______

c) CH₃(CH₂)₁₀COOH ______

d) CH₃(CH₂)₇CH=CH(CH₂)₇COOH ______

e) CH₃(CH₂)₄CH=CH-CH₂-CH=CH(CH₂)₇COOH ______