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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 ]
The most famous example is the hyperchromicity of DNA that occurs when the DNA duplex is denatured. [1] The UV absorption is increased when the two single DNA strands are being separated, either by heat or by addition of denaturant or by increasing the pH level. The opposite, a decrease of absorbance is called hypochromicity.
Slipped strand mispairing is one explanation for the origin and evolution of repetitive DNA sequences. [1] It is a form of mutation that leads to either a trinucleotide or dinucleotide expansion, or sometimes contraction, during DNA replication. [2] A slippage event normally occurs when a sequence of repetitive nucleotides (tandem repeats) are ...
The PCR tubes are then placed in a thermal cycler to begin cycling. In the first cycle, the synthesis of cDNA occurs. The second cycle is the initial denaturation wherein reverse transcriptase is inactivated. The remaining 40-50 cycles are the amplification, which includes denaturation, annealing, and elongation.
The process of DNA denaturation can be used to analyze some aspects of DNA. Because cytosine / guanine base-pairing is generally stronger than adenine / thymine base-pairing, the amount of cytosine and guanine in a genome is called its GC-content and can be estimated by measuring the temperature at which the genomic DNA melts. [2]
Translation can also be regulated via helper proteins. For example, a protein called eukaryotic initiation factor-2 can bind to the smaller subunit of the ribosome, starting translation. When elF-2 is phosphorylated, it cannot bind to the ribosome and translation is halted. [16]
Each double-stranded DNA has a 'critical temperature' (Tc) lower than its Tm. The PCR amplification efficiency drops measurably below the Tc. The Tc is dependent on DNA sequence. Two template DNA fragments differing by only one or two nucleotide mismatches will have different amplification efficiencies if the denaturation step of PCR is set to ...
The human genome codes for 95 non-redundant helicases: 64 RNA helicases and 31 DNA helicases. [2] Many cellular processes, such as DNA replication, transcription, translation, recombination, DNA repair, and ribosome biogenesis involve the separation of nucleic acid strands that necessitates the use of helicases. Some specialized helicases are ...