Separation DNA molecules

A structural feature of the T7 DNA which is important in DNA replication is that there is a direct terminal repeat of 160 base pairs at the ends of the molecule. In order to replicate DNA near the 5 terminus, RNA primer molecules have to be removed before replication is complete. There is thus an unreplicated portion of the T7 DNA at the 5 terminus of each strand. The opposite single 3 strands on two separate DNA molecules, being complementary, can pair with these 5 strands, forming a DNA molecule twice as long as the original T7 DNA. The unreplicated portions of this end-to-end bimolecular structure are then completed through the action of... 

The thermodynamically favored structure of DNA under physiological conditions is an ordered double-stranded helix formed of two separate DNA molecules held together by noncovaient interactions. The duplex structure is most stable when all opposing bases are complementary, allowing... 

In order to manipulate or sequence a cloned DNA fragment. It first must be separated from the vector DNA. This can be accomplished by cutting the recombinant DNA clone with the same restriction enzyme used to produce the recombinant vectors originally. The cloned DNA and vector DNA then are subjected to gel electrophoresis, a powerful method for separating DNA molecules of different size. 

EXPERIMENTAL FIGURE 9-21 Gel electrophoresis separates DNA molecules of different lengths. A gel is... 

The Schwartz and Cantor method was capable of separating DNA molecules of up to 2000 kb in size. 

The solution is then cooled to 60°C allowing new hydrogen bonds to form [Fig ure 28 14(c)] However the reaction mixture contains much larger concentrations of two primer molecules than DNA and the new hydrogen bonds are between the separated DNA strands and the primers rather than between the two strands... 

The protein dimer binds so that the recognition a helices at opposite ends of the protein molecule are in the major groove of the DNA as predicted, where they interact with base pairs at the end of the DNA molecule. Since these binding sites are separated by one turn of the DNA helix, it follows that at the center of the DNA molecule the narrow groove faces the protein... 

The amplification of genetic information, i.e., the replication of parent DNA molecules, is achieved by means of an entire set of enzymes. The major players are a DNA-gyrase for unwinding of the double helix, proteins to separate the two antiparallel DNA strands at the replicational junction, single-stranded binding proteins (SSB) that prevent the... 

The double-stranded structure of DNA can be separated into two component strands (melted) in solution by increasing the temperature or decreasing the salt concentration. Not only do the two stacks of bases puU apart but the bases themselves unstack while still connected in the polymer by the phosphodiester backbone. Concomitant with this denaturation of the DNA molecule is an increase in the optical absorbance of the purine and pyrimidine bases—a phenomenon referred to as hyperchromicity of denaturation. Because of the... 

Han, j., Craighead, H. G., Separation of long DNA molecules in a micro-fabricated trap array. Science 288 (2000) 1026-1029. 

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