Template remaining/residual

Other urgent improvements concern the mass transfer properties of the materials and bleeding of residual traces of template remaining entrapped in the material.4 The latter properties are influenced by the polymer morphology, which in turn is affected by the type and amount of cross-linking monomer, and the type of porogenic solvent. 

Unlike DNA polymerase, RNA polymerase does not require a primer to initiate synthesis. Initiation occurs when RNA polymerase binds at specific DNA sequences called promoters (described below). The 5 -triphos-phate group of the first residue in a nascent (newly formed) RNA molecule is not cleaved to release PPj, but instead remains intact throughout the transcription process. During the elongation phase of transcription, the growing end of the new RNA strand base-pairs temporarily with the DNA template to form a short hybrid... 

The RNA world hypothesis requires a nucleotide polymer to reproduce itself. Can a ribozyme bring about its own synthesis in a template-directed manner The self-splicing rRNA intron of Tetrahymena (Fig. 26-26) catalyzes the reversible attack of a guanosine residue on the 5 splice junction (Fig. 26-37). If the 5 splice site and the internal guide sequence are removed from the intron, the rest of the intron can bind RNA strands paired with short oligonucleotides. Part of the remaining intact intron effectively acts as a template for the... 

Figure 3 Design of the DNA template and primer for the in vitro primer extension synthesis of DNA with the Klenow fragment. The product DNA (shown in lower case italics) is covalently attached to the 3 -terminus of the primer. For convenience, the template and primer are combined in a single monomolecular hairpin construct in this example. The primer ends with a single RNA residue (boxed) the site of the alkaline cleavage is shown with an arrow. If the RNA residue is placed several positions upstream in the primer, the portion of the primer downstream of that ribonucleotide will remain attached to the product DNA after the alkaline cleavage, and will therefore remain unlabeled.

As mentioned above, a certain number of sites in the MIP remain inaccessible. This can be due to the presence of residual template molecules, excessive cross-linking limiting diffusion, or deformation of the network. In covalent systems, 80 to 90% of the sites vacated can be occupied again in non-covalent systems, the proportion of reinsertion falls to 10 to 15% [135]. Non-covalent systems therefore provide low-capacity materials. This difference of behaviour is apparent from Fig. 13 [136b,c]. 

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