Consider the following statements:

(i) Tertiary structure  gives us a 3-dimensional view of a protein.

(ii) The positional information of amino acids in a protein is provided by its primary structure.

(iii) The last amino acid in a protein is called N-terminal.

(iv) Adult human haemoglobin consists of three subunits of α type and one subunit of β type together constitute the human haemoglobin (Hb).

Which of the above statements are correct?

(i) and (ii)

The correct answer is Option (1) –(i) and (ii)

The sequence of amino acids i.e., the positional information in a protein – which is the first amino acid, which is second, and so on – is called the primary structure of a protein. A protein is imagined as a line, the left end represented by the first amino acid and the right end represented by the last amino acid. The first amino acid is also called as N-terminal amino acid. The last amino acid is called the C-terminal amino acid. 

 In addition, the long protein chain is also folded upon itself like a hollow woolen ball, giving rise to the tertiary structure . This gives us a 3-dimensional view of a protein. Tertiary structure is absolutely necessary for the many biological activities of proteins. Some proteins are an assembly of more than one polypeptide or subunits. The manner in which these individual folded polypeptides or subunits are arranged with respect to each other (e.g. linear string of spheres, spheres arranged one upon each other in the form of a cube or plate etc.) is the architecture of a protein otherwise called the quaternary structure of a protein .

Adult human haemoglobin consists of 4 subunits. Two of these are identical to each other. Hence, two subunits of α type and two subunits of β type together constitute the human haemoglobin (Hb).