1. A peptide is formed by joining amino acids through peptide bonds (amide linkages).

2. If $n$ amino acid molecules combine to form one linear peptide chain, then the number of peptide linkages formed is: $n-1$ This is because each linkage joins two amino acids, and joining $n$ units into one chain requires one fewer bond than the number of units.

3. Here, the peptide is synthesized from one molecule each of:

• Glycine
• Leucine
• Aspartic acid
• Histidine

So total number of amino acid molecules is: $n=4$

4. Therefore, number of peptide linkages is: $4-1=3$

5. Hence, the peptide will have: $\boxed{3}$ peptide linkages.