ppt模板紫色地球信息主題(編輯修改稿)
2025-06-06 19:19 本頁面
【文章內容簡介】 help protect the DNA ends, and stop the DNA repair systems in the cell from treating them as damage to be corrected.[45] In human cells, telomeres are usually lengths of singlestranded DNA containing several thousand repeats of a simple TTAGGG sequence.[46] ? DNA quadruplex formed by telomere repeats. The looped conformation of the DNA backbone is very different from the typical DNA helix.[47] ? These guaninerich sequences may stabilize chromosome ends by forming structures of stacked sets of fourbase units, rather than the usual base pairs found in other DNA molecules. Here, four guanine bases form a flat plate and these flat fourbase units then stack on top of each other, to form a stable Gquadruplex structure.[48] These structures are stabilized by hydrogen bonding between the edges of the bases and chelation of a metal ion in the centre of each fourbase unit.[49] Other structures can also be formed, with the central set of four bases ing from either a single strand folded around the bases, or several different parallel strands, each contributing one base to the central structure. 樣例文本 C ? 脫氧核糖核酸有多種不同的構象，
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