複選題24. BrdU is an analog of thymine that can be incorporated into double stranded DNA during DNA polymerization in. S phase. Unsynchronized cells at various stages of cell cycle are first treated with BrdU for 2 hours and then cultured in the absence of BrdU for another 4 hours. What would happen to those unsynchronized cells exposure to BrdU? (A) BrdU is incorporated into all the unsynchronized cells. (B) If a cell is labeled by BrdU, only one of the sister chromatins is labeled. (C) If a cell is labeled by BrdU, only one strand of DNA is labeled. (D) In the 2-hour BrdU pulse, only mitotic cells are labeled. (E) In the 2-hour BrdU pulse, only mitotic cells are not labeled.