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#primer binding

2 public questions tagged with this topic.

PCR

PCR step where primers bind to template

A PCR cycle comprises three precisely controlled steps governed by temperature. Denaturation at 94-95°C separates double-stranded DNA into single strands by breaking hydrogen bonds. Annealing at 50-65°C allows short synthetic oligonucleotide primers to bind to complementary sequences on each template strand via Watson-Crick base pairing and electrostatic stabilization. Extension at 72°C enables Taq polymerase to elongate primers synthesizing new strands. If primer binding fails during annealing, initiation cannot occur and no amplicon is generated. Thus productive primer-template hybridization

Ref: NCERT Biology Class XII Principles on Klenow fill-in labeling, Lehninger Chapter 9 DNA cloning techniques, and Molecular Cloning by Sambrook Chapter 10 documenting end-labeling of cohesive termini.

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PCR

Correct annealing temperature (TA) during PCR is

Melting temperature, Tm, is the temperature at which half the primer-template duplex dissociates. Annealing temperature, TA, must be set below Tm to permit stable hydrogen bonding between primer and complementary template while maintaining specificity. Typically TA is adjusted 3-5°C below Tm, preventing non-specific binding caused by too low temperature and poor efficiency caused by temperature equal to or above Tm where duplexes are unstable. This empirical optimization balances yield and specificity and is calculated from GC and AT composition for each primer pair.

Ref: NCERT Biology Class XII Principles on Klenow fill-in labeling, Lehninger Chapter 9 DNA cloning techniques, and Molecular Cloning by Sambrook Chapter 10 documenting end-labeling of cohesive termini.

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