Question

Draw the structural formula of a lecithin containing one molecule each of palmitic acid and linoleic acid.

Short answer

Question: Draw the structural formula of a lecithin containing one molecule each of palmitic acid and linoleic acid. Answer: The lecithin molecule with palmitic acid and linoleic acid has the following structural formula: ``` CH3-(CH2)14-COO-Glycerol backbone-P(=O)(O-)-Choline CH3-(CH2)4-CH=CH-CH2-CH=CH-(CH2)7-COO- ```

Step-by-step solution

Draw the structural formula of the palmitic acid molecule

Palmitic acid, also known as hexadecanoic acid, is a saturated fatty acid with the molecular formula C16H32O2. It has the following structural formula: ``` CH3-(CH2)14-COOH ``` We start with a methyl group (CH3), follow with a chain of 14 methylene groups (CH2), and end with a carboxylic acid group (COOH).

Draw the structural formula of the linoleic acid molecule

Linoleic acid is a polyunsaturated fatty acid with the molecular formula C18H32O2. It has two double bonds in its structure, present as cis double bonds. The structural formula for linoleic acid is: ``` CH3-(CH2)4-CH=CH-CH2-CH=CH-(CH2)7-COOH ``` This fatty acid chain starts with a methyl group (CH3), followed by 4 methylene groups (CH2), a cis double bond (CH=CH), one methylene group (CH2), another cis double bond (CH=CH), seven methylene groups (CH2), and ends with a carboxylic acid group (COOH).

Draw the structural formula of a lecithin molecule

Lecithin is a phospholipid containing a glycerol molecule (as a backbone), two fatty acids, and a phosphate group (with a choline head group). The general structure of a lecithin molecule with two fatty acid tails is: ``` R1COO-Glycerol backbone-P(=O)(O-)-Choline R2COO- ``` R1 and R2 are the fatty acid chains, and we need to replace them with the palmitic and linoleic acid chains to create the required lecithin molecule.

Combine the structures to form the desired lecithin molecule

Replace R1 with palmitic acid and R2 with linoleic acid: ``` CH3-(CH2)14-COO-Glycerol backbone-P(=O)(O-)-Choline CH3-(CH2)4-CH=CH-CH2-CH=CH-(CH2)7-COO- ``` This is the structure of the lecithin molecule containing one molecule each of palmitic acid and linoleic acid.