Linear polynucleotide chains

Osmium tetroxide is an electroactive marker of the polynucleotide chain and is a good probe of the DNA structure since dsDNA is modified by osmium to a much lesser extent than single-stranded polynucleotides. The limit of detection of osmium-labelled DNA was below 5 ng cm-3 after 2 min accumulation time [66]. Adsorptive stripping linear sweep voltammetry of osmium tetroxide labelled DNA at a mercury electrode [66, 67] was shown to be a good sensor for hybridization of DNA. 

DNA consists of units, called nucleotides (several hundred), that are held together by chemical bonds in a linear array, called a polynucleotide chain or a nucleic acid molecule. Each nucleotide consists of three parts a molecule of phosphoric acid, a molecule of a sugar, deoxyrihose (Section 13-6), and a molecule of a nitrogen compound, called a nitrogen base. The molecules of sugar and molecules of phosphoric acid are condensed together to form long chains ... 

C below the Tm of duplex AAV DNA. These duplex linear monomers did form duplex circular monomers and hnear dimers when exposed to annealing conditions. Thus, anneahng of intact linear AAV single polynucleotide chains led to the formation of two types of duplex linear monomers (1) those without cohesive single-stranded termini, and (2) those with cohesive single-stranded termini. 

Fig. 6. Electron micrographs of hydrogen-bonded single-stranded circles formed when purified linear heavy AAV single polynucleotide chains are exposed to annealing conditions. The arrows point to the projections observed on such single-stranded circles...

The current model of the purified DNA is that it is a linear single polynucleotide chain containing a limited number of nucleotide sequence permutations, the start points of which occur within a region representing less than 6% of the genome, and also containing a terminal nucleotide sequence repetition (either inverted, natural, or both). 

The bulk of all carbohydrates in nature exists in the form of polysaccharides. These are very large molecules formed by linking together long chains of monosaccharide units. These chains may be linear, like polypeptides or polynucleotides, or branched. They may contain a single type of monosaccharide unit, similar to polyglycine or polyA for example, or two or more types of monosaccharide, like nucleic acids (four types of nucleotides) or proteins (20 types of amino acids). However, polysaccharides that contain more than two types of monosaccharide are rare in nature. 

Polymers The word polymer means a material composed of macromolecules or the macromolecule itself. Most synthetic organic polymers consist of long chains of mostly or all carbon-carbon bonds. To build nanostmetured materials, the polymeric building blocks can be linear, highly branched, or amphiphiUc. Likewise the far more complex assemblies of living organisms depend on polymers polysaccharides, proteins, and polynucleotides. 

Another variation of the classical primary polynucleotide structure (10.90a) was established by the synthesis of derivatives based on hexose rings (10.92b). The use of the latter in place of ribose rings produces a more linear chain which forms a non-helical double-stranded arrangement. However, some of these polyhexose chains appear to form double-stranded arrangements more stable than duplex DNA built from (10.92a). Similarly for RNA analogues [62]. 

Oligonucleotides linear sequences of up to 20 nucleotides, joined by phosphodiester bonds. Position 3 of each nucleotide unit is linked via a phosphate group to position 5 of the next unit. In the terminal units, the respective 3 and 5 positions may be free (i.e.-OH groups) or phosphorylated. O. are named according to chain length, i. e. di-, tri-, tetra-, pentanu-cleotides, etc. Linear sequences of more than 20 nucleotide units are called Polynucleotides (see and compare). 

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