Practice question

Filamentous bacteriophage M13 provides robust scaffold for displaying heterologous proteins as coat fusions. Genes encoding minor coat protein pIII at tip, typically five copies, or major coat protein pVIII, thousands of copies, are engineered to incorporate foreign cDNA at N-terminus. Resulting fusion is incorporated into virion during assembly in Escherichia coli without abolishing infectivity. This presentation links protein phenotype to phage genome inside particle for selection. Plasmid vectors, ribosomes, and polymerase lack this genotype-phenotype linkage and are unrelated to phage particle architecture for display.