In: Biology
1. Given the following fatty acids: Caproic Acid,
Valeric Acid, Stearic Acid, Oleic Acid, Arachidonic Acid, Palmitic
Acid, Cerebronic Acid, Timnodonic Acid and Cervonic Acid.
1a. Group them into saturated and unsaturated fatty acids. Identify the number of
carbons and number of double bonds, if present. Give
their biochemical name.
1b. Arrange them based on their melting point, from
lowest to highest.
1c. Which will you select as constituents of the cell membrane? Why?
Part 1a.
Saturated fatty acids | ||||
No. of carbons | No. of double bonds | Melting point | Biochemical name | |
Caproic acid | 6 | 1 | -3.40C | Hexanoic acid |
Valeric acid | 5 | 1 | -34.50C | Pentanoic acid |
Stearic acid | 18 | 1 | 69.30C | Octadecanoic acid |
Palmitic acid | 17 | 1 | 62.90C | Hexadecanoic acid |
Cerebronic acid | 24 | 1 | 101-1040C | 2-Hydroxytetracosanoic acid |
Unsaturated fatty acids | ||||
No.of carbon atoms | No. of double bonds | Melting point | Biochemical name | |
Oleic acid | 18 | 2 | 13-140C | cis-9-octadecenoic acid |
Arachidonic acid | 20 | 5 | -490C | Eicosatetraenoic acid |
Timnodonic acid | 20 | 5 | -540C | Eicosapentaenoic acid |
Cervonic acid | 22 | 6 | -440C | Docosahexaenoic acid |
Part 1b. Arrangement of the fatty acid on the basis of their melting point, from lowest to highest is given below-
Lowest melting point----------------- Timnodonic acid (-540C)
Arachidonic acid (-490C)
Cervonic acid (-440C)
Valeric acid (-34.50C)
Caproic acid (-3.40C)
Oleic acid (13-140C)
Palmitic acid (62.90C)
Stearic acid (69.30C)
Highest melting point-------------- Cerebronic acid (101-1040C)
Part 1c.
Fatty acids affect the rigidity and fluidity of a cell membrane. If a cell membrane is mainly composed of saturated fatty acids, then the membrane would be more rigid and stiff. Movement of solutes would be very less through this type of membrane. However, unsaturated fatty acids are the major constituents of a membrane, then the membrane fluidity would be more. As a result of which, movement of solutes would be very high. So, a membrane should have correct proportion of both saturated and unsaturated fatty acids in order to maintain its stability. Also, fatty acid constituent is dependent on the type of cell membrane. Membranes of arteries and veins require more flexibilty, so they are mainly composed of poly-unsaturated fatty acids like arachidonic acid.