载体在受体菌中的复制起始位点

请看pYES2质粒图谱。已经有大肠杆菌的puc ori和酿酒酵母的2u ori，那个f1 ori有什么用呢？

It's an F1 phage origin. The Ecoli and plasmid ori's are for making double-stranded copies. The phage ori will make a single-stranded copy of anything placed near it in the correct orientation，

您的回答我google也能搜出来，我就是不能理解是什么意思才来问的。