Complementarity
Definition
The property by which each base pairs with only one specific partner (A with T, G with C). Complementarity allows a single strand to serve as a template for synthesising a new strand with a predictable sequence, and it underlies hybridisation assays in which a labelled probe anneals to a target sequence.
- Base pairing rule
- A with T, G with C
- Underlies
- Template-directed strand synthesis
- Also underlies
- Probe hybridisation assays
- Scope
- Applies to DNA and to RNA base pairing (A with U in RNA)
Common questions
How does complementarity make a hybridisation probe work?+
A labelled probe with a sequence complementary to a target region will anneal specifically to that target under the right conditions, and the label is then used to detect or quantify the target, so complementarity is what gives the probe its sequence specificity rather than binding non-target DNA.
Does complementarity guarantee a probe binds only its intended target?+
No. Short or partially matching sequences elsewhere in the genome can still hybridise under low-stringency conditions, so assay stringency, temperature, and salt concentration have to be controlled to ensure the probe binds only its fully complementary target and not near-matches.
Related terms
- Antiparallel Orientation
- The two strands of the DNA double helix run in opposite directions: one strand reads 5' to 3', its complement reads 3'...
- Base Pair (Bp)
- A complementary pairing of nitrogenous bases on opposite strands of double-stranded DNA: adenine with thymine (two hydrogen bonds) or guanine with cytosine...
- Denaturation
- The separation of double-stranded DNA into two single strands by disrupting the hydrogen bonds between base pairs. In PCR, denaturation is achieved...
- Nucleotide
- The monomer unit of nucleic acids. Each nucleotide consists of a five-carbon sugar (deoxyribose in DNA, ribose in RNA), a phosphate group,...
- Phosphodiester Bond
- The covalent linkage between consecutive nucleotides in a strand, formed between the phosphate group and the 3'-OH of the preceding sugar and...