(a) Fig. 4.1 shows part of a DNA molecule. [Figure 4.1] Use Fig. 4.1 to explain how the structure of mRNA differs from the structure of DNA. (b) Fig. 4.2 shows: • the first seven amino acids of the β chain of haemoglobin • the first amino acid in the sequence is valine (Val) • the 21 base pairs in the sequence of DNA that code for these seven amino acids. [Figure 4.2] Table 4.1 shows the triplets of bases that code for seven amino acids. Using Fig. 4.2 and Table 4.1, state what will happen to the sequence of amino acids in the first part of the β chain of haemoglobin: