Part A In mammalian cells, genes that are expressed in a particular cell are rep
ID: 272957 • Letter: P
Question
Part A In mammalian cells, genes that are expressed in a particular cell are reported to undergo replication during the first half of S phase, and genes not expressed in that cell are replicated in the latter half of S phase. Briefly describe an experiment that could lead to this conclusion. You might consider approaches that involve 5-bromouracil incorporation. Drag the appropriate items to their respective bins Reset Help Selectively isolate early-replicating Identify and quantitate gene sequences that have undergone Labeling with 5-bromodeoxyuridine Adding thymidine to a cell culture genes by equilibrium gradient early in S-phase would increase the allows all cells to proceed through the density of genomic regions undergoing replication early cycle until they reach early S phase whereupon they stop progressing. centrifugation after an early BUdR replication, by reannealing with cloned labeling interval, and isolate late- replicating regions of the genome. DNA probes and identifying genes that have undergone a doubling Transferring the cells to thymidine-free medium allows them all to initiate S phase simultaneously Cell synchronizing and microarray analysis Microarray analysis onlyExplanation / Answer
5-Bromouracil or 5BU is a chemical agent which intercalates itself in the DNA and emits fluorescence. This fluorescence can be experimentally quantified to quantize the amount of DNA present in a cell. Thus, loading the cells with 5BU during early or late phase of S-phase would help in determining the number of genes expressed as a representation of amount of DNA present. Thus, the answers can be found as below:
A. Cell synchronization and microarray analysis: Box 2, box 3, box 4, box 5
B. Microarray analysis only: Box 1, Box 4,