A New Chromosome Model
A New Chromosome Model
复制标题
新的染色体模型
作者：
D. De
根据所提出的模型，chronionema是由2个独立的亚单位，每一个连续的骨干残留的非碱性蛋白质。这两个蛋白质骨架在某些结构组织上不同，这些结构组织在交换发生时限制了类似链的重新聚集。DNA片段被组蛋白包裹，彼此平行，大约在100 - 1000之间。与染色丝轴的长度成直角。DNA双链体的每一条链通过共价键连接到蛋白质主链的一端，另一端保持游离。复制开始于两个亚单位从染色丝两端的解旋和逐渐分离;子代染色丝在一端顺时针旋转，在另一端逆时针旋转。复制和解旋同时进行。复制后，两个子DNA片段被一个旧的和一个新的组蛋白包裹。在这个阶段，新合成的残留蛋白质的小片段附着到杂交DNA的未结合末端。残余的蛋白质-DNA-组蛋白复合物以“拉链“方式连接在一起，从染色丝的两端开始，直到它们在一个很可能是着丝粒的地方相遇。该模型用图解说明。
According to the proposed model, the chronionema is composed of 2 separate sub-units, each with a continuous backbone of residual non-basic protein. The 2 protein backbones are unlike in some structural organization that restricts reunion of like strands when exchanges occur. The DNA segments, which are wrapped around with histone, are parallel to each other and approx. at right angles to the length of the chromonema axis. Each strand of the DNA duplex is attached by covalent bonds to one of the protein backbones at one end, the other end remaining free. Replication begins with untwisting and gradual separation of the 2 sub-units from both ends of the chromonema; the daughter ehromonemata rotate clockwise at one end and anti-clockwise at the other. Replication and unwinding proceedpari passu. After replication both of the daughter DNA segments are wrapped around with one old and one new histone protein. At this stage, small pieces of newly synthesised residual protein are attached to the unbound end of the hybrid DNA. Joining together of the residual protein-DNA-histone complexes in " zipper " fashion proceeds from both ends of the chromonema until they meet each other at a place which may well be the centromere. The model is illustrated diagrammatically.