Question

What is the numbering scheme for naming fatty acids and what is the difference between cis and trans fatty acids?

What are the general properities of glycosidic linkages?

Answer 1

Hi Answer:

Numbering scheme for naming fatty acids:

There is two most common naming system of fatty acids i.e. omega and ‘n minus’ system. These both systems are interchangeable and chemists prefer ‘n minus’ system whereas the educators prefer omega system. In this system, the length of the fatty acid is the first number followed by a colon with the second number which denotes the number of double bonds. After that n ‘minus’ a third number may appear which indicates the position of double bond counting from the methyl or omega end of the molecule.

For example 18: 2n-6 means 18 carbon fatty acid with 2 double bond and the first of the double bond occurs at 6 carbons of methyl end of the fatty acid. The actual name of this fatty acid is linoleic acid.

Difference between cis and trans fatty acids

Cis Fatty acid	Trans Fatty acid
Cis fatty acids are commonly found in natural fatty acids.	Trans fatty acids are commonly found in processed food, milk products, and butter.
They have a lower melting point.	They have a higher melting point.
They are naturally available.	Very few exist in nature produced by the partial hydrogenation of polyunsaturated fatty acids.
These fatty acids have hydrogen atoms at double bonded carbon atom on the same side.	These fatty acids have hydrogen atoms at double bonded carbon atom on opposite side.
They can be consumed as per requirement.	It is advised to uptake only 1% of total calories consumed per day.
They are loosely packed.	They are closely packed.

What are the general properties of glycosidic linkages?

The glycosidic linkage or glycosidic bond is the type of a covalent bond which joins monosaccharides (sugars) to other carbohydrates and forms them di, oligo, and polysaccharides. In a glycosidic bond, the aldehyde or ketone group of sugar react with the hydroxyl group of the second sugar.

The glycosidic linkage is the result of a condensation reaction between an alcohol or amine group of one molecule and carbon of the sugar, therefore, they may be O-linked or N-linked. The glycosidic linkage is named (1.4 or 1,6) on the bases of the involvement of the which carbon atom of the sugar molecule in the linkage. In 1,4 - glycosidic bond. the carbon atom at number 1 on one sugar and carbon atom at number 4 on another sugar form bond. Similarly in 1,6 glycosidic linkage the carbon number 1 of one sugar and carbon number 6 of second sugar form linkage. The 1, 4 glycosidic linkage is shown in figure below: