Question

dehydration synthesis
in each example of dehydration synthesis, show how the removal of the water molecule(s) takes place by drawing a box around the components of water. then, draw the structural formula of each product.
synthesis of a fat
h
|
h - c - oh
|
h - c - oh
|
h - c - oh
|
h
+
o
||
ho - c - c h₁₅ h₃₁
||
ho - c - c h₁₅ h₃₁
||
ho - c - c h₁₅ h₃₁
1 glycerol molecule + 3 fatty acid molecules → 1 fat molecule + 3 water molecules
formation of a peptide bond
h h o

n - c - c - oh
| |
h h
+
h h o

n - c - c - oh
| |
h h
amino acid + amino acid → dipeptide + water

Explanation:

Step1: Analyze synthesis of a fat

In the synthesis of a fat from glycerol and fatty - acids, each hydroxyl group ($-OH$) of glycerol reacts with the carboxyl group ($-COOH$) of a fatty - acid. The components of water ($H$ from glycerol and $OH$ from fatty - acid) are removed.
For glycerol ($C_3H_8O_3$) with three $-OH$ groups and three fatty - acids (each with a $-COOH$ group), three water molecules are removed. The structural formula of the fat (a triglyceride) is formed by ester bonds between the glycerol and the fatty - acid chains.

Step2: Analyze formation of a peptide bond

In the formation of a peptide bond between two amino acids, the amino group ($-NH_2$) of one amino acid reacts with the carboxyl group ($-COOH$) of another amino acid. The components of water ($H$ from the amino group and $OH$ from the carboxyl group) are removed. The resulting product is a dipeptide with a peptide bond ($-CO - NH-$) connecting the two amino - acid residues.

Answer:

For the synthesis of a fat:

1. Box around the $H$ from glycerol's $-OH$ group and the $OH$ from the fatty - acid's $-COOH$ group for each of the three reactions.
2. The structural formula of the fat (triglyceride) has glycerol connected to three fatty - acid chains via ester bonds ($-CO - O-$).

For the formation of a peptide bond:

1. Box around the $H$ from the amino group of one amino acid and the $OH$ from the carboxyl group of the other amino acid.
2. The structural formula of the dipeptide has a peptide bond ($-CO - NH-$) connecting the two amino - acid residues.