Monday, February 27, 2012

Biological molecules tutorial (Protein recap): Response to questions posed in class today


Q1) Amino acids can be ionised in solution (i.e. Amino/NH2 group becomes NH3+, and Carboxyl/COOH group becomes COO-), hence they are soluble in water. So why can't the NH3+ and COO- groups form ionic bonds with each other?

A1) This is because the NH2 and COOH groups are involved in peptide bond formation. Hence ionic bonds in proteins can only be formed between the charged R groups.

Unionised form of amino acid






Ionised form of amino acid


Q2) FYI: What is the difference between haemoglobin and myoglobin?

A2) - Haemoglobin is found in red blood cells while myoglobin is found in muscle tissue.
- Haemoglobin consists of four polypeptide chains while myoglobin consists of one polypeptide chain.
- Haemoglobin transports oxygen while myoglobin stores oxygen (that is used during periods of oxygen deprivation).

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