(2)DNA helicase can untie double-stranded DNA, but it needs energy (ATP) from cells. In addition to the helicase and DNA polymerase shown in the figure, DNA ligase is also needed to synthesize C-DNA molecules.
(3)DNA molecule is a unique double helix structure, which consists of two parallel deoxynucleotide chains, and the replication is from 5' to 3', so the synthesis directions of the two sub-chains are opposite.
(4)DNA is mainly distributed in the nucleus, and mitochondria and chloroplasts also contain a small amount of DNA, so the places where DNA replicates in cells are the nucleus, mitochondria and chloroplasts; After replication, B and C are located on sister chromatids and separated after centromere division, so the separation period of B and C is late mitosis and late meiosis.
So the answer is:
(1) semiconservative replication
(2) Energy
(3) On the contrary
(4) Late mitosis and second meiosis of nuclei, mitochondria and chloroplasts.