Practice question

Library construction requires matching insert size to vector stability and transfer efficiency. Cosmid and fosmid systems accommodate about 40-45 kb, suitable for medium libraries but suffer packaging limits. P1 phage-derived artificial chromosome uses P1 bacteriophage replication and packaging system, stably maintaining inserts around 70-100 kb with less chimerism than YAC systems. BAC also handles 100-300 kb but for 70 kb mid-range genomic libraries, P1 vector offers superior efficiency, lower rearrangement than YAC and single-copy stability. Therefore for approximately 70 kb libraries requiring high fidelity and moderate throughput, P1 system represents optimal choice.