試題詳解

27. 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 treate 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