Question

1. What characteristics account for the complexity of proteins as a macronutrient as compared with carbohydrates and lipids?
2. How would you explain to an individual the role of protein in the development of edema?

Answer 1

1. Proteins are, indeed, much more complex and diverse than any other macronutrients such as carbohydrates and lipids because of the following reasons:

• Proteins are polymers of amino acids. Each protein can have all of the amino acids incorporated into the chain at any given time. This diversity in the monomeric units is not seen in any other macromolecule. Even carbohydrate has maximum 2 monomeric units incorporated into polymerized chains.
• Unlike carbohydrates and lipids that only contain carbon (C), hydrogen (H) and oxygen (H), the structural organization of proteins is much more diverse because of the presence of additional elements such as nitrogen (N), sulphur (S), etc in the amino acids.
• Protein chains have vrious levels of structural organization. They can be arranged in secondary form, tertiary form or quaternary form. These different structures require different kinds of bonds to hold the polypeptide chains.

2. Edema is a condition in which part of the body becomes swollen. This condition arises due to accumulation of fluid in tissues. A low protein level in the blood can make fluid leak out of the blood vessels into the tissue and get accumulated there. The predominant protein in blood is albumin. A lack of protein in blood could be associated with a liver or kidney disease that causes more protein to be lost in urine, or with a low protein diet which causes malnutrition.