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DNA denaturation occurs when hydrogen bonds between base pairs are disturbed. The non-covalent interactions between antiparallel strands in DNA can be broken in order to "open" the double helix when biologically important mechanisms such as DNA replication, transcription, DNA repair or protein binding are set to occur. [19]
This is because DNA polymerase requires the 3' OH group of the growing chain and the 5' phosphate group of the incoming dNTP to create a phosphodiester bond. [2] Sometimes the DNA polymerase will incorporate a ddNTP and the absence of the 3' OH group will interrupt the condensation reaction between the 5' phosphate (following the cleavage of ...
Before annealing can occur, one of the strands may need to be phosphorylated by an enzyme such as kinase to allow proper hydrogen bonding to occur. The term annealing is often used to describe the binding of a DNA probe , or the binding of a primer to a DNA strand during a polymerase chain reaction .
Alternatively, juxtapositioned probes (one featuring a fluorophore and the other, a suitable quencher) can be used to determine the complementarity of the probe to the target sequence. [ 3 ] The graph of the negative first derivative of the melting-curve may make it easier to pin-point the temperature of dissociation (defined as 50% ...
DNA polymerase, the main enzyme to catalyze the polymerization of free deoxyribonucleotides into a newly forming DNA strand, plays a significant role in the occurrence of this mutation. When DNA polymerase encounters a direct repeat, it can undergo a replication slippage. [4] Strand slippage may also occur during the DNA synthesis step of DNA ...
A DNA polymerase may perform this replacement via nick translation, a terminal excision reaction by its 5' 3' exonuclease activity, followed by a fill-in reaction by its polymerase activity. DNA ligase then forms a phosphodiester bond to seal the resulting nicked duplex product, which now includes a new, correct cytosine ( Base excision repair ).
Thus the denaturation can occur at the Tc, proceed to primer annealing, and then polymerase-mediated extension. Each round of amplification will include these three stages in that order. By utilizing the lower denaturation temperature, the reaction will discriminate toward the products with the lower Tm – i.e. the variant alleles.
The average DNA polymerase requires about one second locating and binding a primer/template junction. Once it is bound, a nonprocessive DNA polymerase adds nucleotides at a rate of one nucleotide per second. [14]: 207–208 Processive DNA polymerases, however, add multiple nucleotides per second, drastically increasing the rate of DNA synthesis ...