annealing

(noun)

Annealing, in genetics, means for complementary sequences of single-stranded DNA or RNA to pair by hydrogen bonds to form a double-stranded polynucleotide. The term 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 (PCR). The term is also often used to describe the reformation (renaturation) of complementary strands that were separated by heat (thermally denatured). Proteins such as RAD52 can help DNA anneal.

Examples of annealing in the following topics:

  • Amplifying DNA: The Polymerase Chain Reaction

    • Annealing step: The reaction temperature is lowered to 50-65 °C for 20-40 seconds allowing annealing of the primers to the single-stranded DNA template.
    • Annealing at 68°C. 3.

  • Primer Extension Analysis

    • The primer is allowed to anneal to the RNA and reverse transcriptase is used to synthesize cDNA from the RNA until it reaches the 5' end of the RNA.

  • Multiplex and Real-Time PCR

    • The PCR process can be divided into three steps: DNA denaturation where double-stranded DNA (dsDNA) is separated at temperatures above 90°C, oligonucleotide primers annealing at 50–60°C, and primer extension at 70–78°C.
    • The key to successful multiplex PCR is the ability to define a single set of reaction parameters (reagent concentrations and cycling parameters) that allows for all primers to anneal with high specificity to their target sequences and be extended with the same efficiency.

  • Synthesizing DNA

    • The main method is currently by oligonucleotide synthesis (also used for other applications) from digital genetic sequences and subsequent annealing of the resultant fragments.

  • Coupling Specific Genes to Specific Organisms Using PCR

    • If the gene is not present, the primers will not anneal and no amplification will occur.

  • Obtaining DNA

    • Annealing at 68°C. 3.