科学家已经利用单分子分析研究了DNA复制的基本细胞过程，这可能为DNA复制的机制提供见解，并阐明这类高分辨率研究的效用。
在DNA复制期间，一大群蛋白质和酶让双螺旋解旋，并合成出与父链互补的新的DNA链。DNA合成是被一个叉形的连续动作引导的，两个分支——分别称为先导链和后随链——加入到了螺旋结构中。这种蛋白质群称为复制体，它与DNA聚合酶连在一起，后者把核苷加到先导链和后随链上，这两个链是同时合成的。
在实时实验中，Mike O’Donnell及其同事分析了大肠杆菌复制体在DNA复制期间的运动，这让他们可以既研究DNA复制率，又研究聚合酶的连续性（连续性衡量的是这种酶离开DNA之前把多少核苷加到了正在复制的链上）。这组作者说，尽管后随链合成显著增加了复制体的连续性，它减少了复制叉过程的总体复制率。（生物谷Bioon.com）
生物谷推荐原始出处：
PNAS August 3, 2009, doi: 10.1073/pnas.0906157106
Single-molecule analysis reveals that the lagging strand increases replisome processivity but slows replication fork progression
Nina Y. Yao,1, Roxana E. Georgescu,1, Jeff Finkelstein and Michael E. O'Donnell,2
1 Howard Hughes Medical Institute, Rockefeller University, 1230 York Avenue, New York, NY 10021
Single-molecule techniques are developed to examine mechanistic features of individual E. coli replisomes during synthesis of long DNA molecules. We find that single replisomes exhibit constant rates of fork movement, but the rates of different replisomes vary over a surprisingly wide range. Interestingly, lagging strand synthesis decreases the rate of the leading strand, suggesting that lagging strand operations exert a drag on replication fork progression. The opposite is true for processivity. The lagging strand significantly increases the processivity of the replisome, possibly reflecting the increased grip to DNA provided by 2 DNA polymerases anchored to sliding clamps on both the leading and lagging strands.
