Try it on paper first. A hint, the key idea and the worked solution are here when you need them.
Adult haemoglobin has two alpha chains of amino acids each and two beta chains of amino acids each.
An amino acid has a hydrogen atom, an amino group, a carboxyl group and an R group on the alpha carbon. Twenty kinds build proteins: acidic, basic, neutral and aromatic by the R group. In water an amino acid is a zwitterion. A peptide bond joins carboxyl to amino and releases a water, so a chain of n amino acids has n minus 1 bonds. Levels: primary (sequence), secondary (helix), tertiary (fold), quaternary (subunits, as in haemoglobin).
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. (a) bonds.
Step 2. (b) bonds.
Step 3. (c) bonds.
Step 4. (d) One water leaves at each peptide bond, so molecules.
Answer: ; ; ; .
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