A-LevelBiologyNucleic acids and protein synthesisMay/June 2025Paper 2 Q419 Marks
Cells of the immune system have cell surface receptors that detect molecules made by pathogens. One of these cell surface receptors is known as TLR8. The gene TLR8 is found on the X chromosome in humans. Fig. 4.1 shows the production of messenger RNA (mRNA) formed from the gene TLR8 in the nucleus of a macrophage. The nucleotide sequence TTAGGG is repeated in the direction 5' to 3' in the telomeres of human chromosomes. Melanoma is a type of tumour that develops from pigment-producing skin cells known as melanocytes. A melanoma tumour is cancerous and may spread to other parts of the body. T-vec is a new drug that has been developed to treat melanoma that has spread to other parts of the body, including lymph nodes. T-vec contains a virus that infects some of the melanoma cells, causing the cells to burst and release their contents. Some of the contents of the melanoma cells act as cytokines and others act as antigens. [Figure 4.1]
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