Cathelicidin LL-37 is a cell signalling compound that stimulates many different cells in humans. One role of cathelicidin LL-37 is stimulating the production of endothelial cells in the formation of capillaries during wound healing. Cathelicidin LL-37 is a protein composed of 37 amino acids. Table 5.1 shows: • the sequence of the first 10 amino acids in the primary structure of cathelicidin LL-37 • DNA triplets in the non-transcribed strand in the gene that codes for the first 10 amino acids in the primary structure of cathelicidin LL-37. Table 5.1 amino acid position 1 2 3 4 5 6 7 8 9 10 amino acid leu leu gly asp phe phe arg lys ser lys DNA triplet CTG CTG GGT GAT TTC TTC CGG AAA TCT AAA Table 5.2 shows the triplets of bases in DNA and the amino acids for which they code. Table 5.2 [Figure 5.2 (Genetic Code Table)]

1. (a)(i)Explain how it is possible for many different cell types to respond to the same cell signalling compound.[2]
2. (a)(ii)Describe the appearance of the endothelial cells of a capillary.[2]
3. (b)(i)Use the information in Table 5.1 and Table 5.2 to suggest the effect on the primary structure of cathelicidin LL-37 of: the substitution of the base T with the base A in the middle of the triplet at position 5[1]
4. (b)(ii)the deletion of base T in the triplet at position 2[2]
5. (b)(iii)the insertion of base G between bases G and T in the triplet at position 3.[2]
6. (c)The genetic code is described as universal. Explain why the genetic code is described as universal.[1]
7. (d)Use Table 5.2 to explain why some mutations have no effect on the primary structure of a protein.[2]

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