Molecular beacon

Definition

A molecular beacon is a type of nucleic acid probe that fluoresces upon hybridization with its target sequence. It is used for detecting specific sequences of DNA or RNA in various biological samples.

5 Must Know Facts For Your Next Test

1. Molecular beacons consist of a stem-loop structure with a fluorescent dye at one end and a quencher at the other.
2. In the absence of the target sequence, the beacon remains non-fluorescent due to close proximity of the quencher to the fluorophore.
3. Upon binding to its target sequence, the stem-loop structure opens, separating the fluorophore from the quencher and resulting in fluorescence.
4. Molecular beacons are highly specific, allowing them to distinguish between sequences that differ by even a single nucleotide.
5. They are widely used in real-time PCR, gene expression studies, and SNP detection.

Review Questions

• What happens to a molecular beacon when it binds to its target sequence?
• How does a molecular beacon achieve specificity for its target DNA or RNA sequence?
• Name two applications where molecular beacons are commonly used.

Related terms

Fluorescence Resonance Energy Transfer (FRET): A technique used to monitor interactions between two molecules based on energy transfer from a donor fluorophore to an acceptor fluorophore.

Real-Time PCR: A laboratory technique used to amplify and simultaneously quantify a targeted DNA molecule.

Single Nucleotide Polymorphism (SNP): A variation in a single nucleotide that occurs at a specific position in the genome.