In phi X 174 phage, whose genome is a single-stranded, circular DNA known as the - strand, replication occurs by the rolling circle method. In which order must the events of replication occur?
A)nicking of the - strand, binding of relaxase protein to the 5′ end, DNA synthesis of a + strand, separation of + from - strands, circularization of both strands
B)synthesis of a + strand, nicking at the origin, binding of protein to the 5′ end, DNA synthesis, displacement of the + strand when replication passes the origin, circularization of the + strand
C)synthesis of a + strand, nicking of both strands to separate them, recircularization of both strands
D)binding of a protein at the origin of the - strand, synthesis of a + strand, release of the + strand

Question

Quizplus · Accepted Answer

The rolling circle method of replication in phi X 174 phage involves the synthesis of a complementary + strand, followed by nicking at the origin and displacement of the original - strand as replication proceeds. The newly synthesized + strand is then circularized to form the final double-stranded DNA molecule. Binding of a protein to the 5′ end is not necessary for replication in this system.

In Phi X 174 Phage, Whose Genome Is a Single-Stranded