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An individual strand of DNA is referred to as positive-sense (also positive (+) or simply sense) if its nucleotide sequence corresponds directly to the sequence of an RNA transcript which is translated or translatable into a sequence of amino acids (provided that any thymine bases in the DNA sequence are replaced with uracil bases in the RNA ...
For example, the positive charge of ethidium bromide can reduce the DNA movement by 15%. [12] Agarose gel electrophoresis can be used to resolve circular DNA with different supercoiling topology. [16] DNA damage due to increased cross-linking will also reduce electrophoretic DNA migration in a dose-dependent way. [17] [18]
The negative charge of its phosphate backbone moves the DNA towards the positively charged anode during electrophoresis. However, the migration of DNA molecules in solution, in the absence of a gel matrix, is independent of molecular weight during electrophoresis, i.e. there is no separation by size without a gel matrix. [12]
DNA gel electrophoresis is usually performed for analytical purposes, often after amplification of DNA via polymerase chain reaction (PCR), but may be used as a preparative technique prior to use of other methods such as mass spectrometry, RFLP, PCR, cloning, DNA sequencing, or southern blotting for further characterization.
DNA exists in many possible conformations that include A-DNA, B-DNA, and Z-DNA forms, although only B-DNA and Z-DNA have been directly observed in functional organisms. [14] The conformation that DNA adopts depends on the hydration level, DNA sequence, the amount and direction of supercoiling, chemical modifications of the bases, the type and ...
DNA ligase is able to form a phosphodiester bond between the nucleotides on each side of the gap. [2] Phosphodiesters are negatively charged at pH 7. [5] The negative charge attracts histones, metal cations such as magnesium, and polyamines [needs citation]. Repulsion between these negative charges influences the conformation of the polynucleic ...
The positive charge on a histone is always neutralized upon acetylation, creating euchromatin which increases transcription and expression of the target gene. [16] Lysine residues 9, 14, 18, and 23 of core histone H3 and residues 5, 8, 12, and 16 of H4 are all targeted for acetylation. [17] [18]
Addition of an acetyl group, which carries a negative charge, effectively removes the positive charge and hence, reduces the interaction between the histone tail and the nucleosome. [18] This opens up the usually tightly packed nucleosome and allows transcription machinery to come into contact with the DNA template, leading to gene transcription.