3载体设计 粘粒 p BamHⅡ cos amp' cos Cosmid vector ori Cosmid vector 37~52kb ~5kb BamHI insert ori BamHI cos cos H3 载体设计——粘粒 ori ampr Cosmid vector ~5kb cos BamHI ori ampr Cosmid vector 37~52kb cos BamHI BamHI insert cos cos insert