( 2 ) average insert size of the library is 118 kb evaluated from analysis of 452 bacs randomly picked from library . so the genome coverage of the library is 13 . 34 and the possibility to find a single - copy gene in the library is 99 . 984 % ( 2 )对随机挑选的452个bac克隆的插入片段进行鉴定估计文库的平均插入为118kb ,文库的基因组覆盖率为13 . 34倍,预计从文库中筛选到单拷贝基因的机率为99 . 984 。