Compounds and methods for site-directed mutations in eukaryotic cells

The invention relates to the polynucleotide, wherein first chain comprising a ribonucleotide and deoxy-ribonucleotide two, a second chain has a, deoxy-ribonucleotideThe chain is watson - Krick on a pair; and a oligonucleotide, connected with the polynucleotide at most with a single 3 ' end and 5 ' end. A is the terminals, a polynucleotide is a single of cyclic polymer (a continuous the polymer). The polynucleotide can be applied to introduce the special to change the target gene.