BRAINCAKEGene Probes
A gene probe is a short, single-stranded piece of DNA or RNA with a base sequence complementary to a particular gene or allele. It is labelled with a radioactive isotope or a fluorescent tag so that it can be detected. When a probe meets its target, it binds (hybridises) by complementary base pairing.
Detecting alleles
Probes can be designed to bind only to one allele, such as a mutant allele that causes a genetic disorder. A person's DNA is denatured to single strands and the probe is added. If the probe binds, and is detected after washing off unbound probe, the person has that allele. This is used in genetic screening, for example to identify carriers of cystic fibrosis.
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Key terms in this lesson
- reverse transcriptase
- An enzyme that synthesises a complementary DNA strand from an RNA template.
More in Gene Expression
- Gene Expression
- Control of Gene Expression
- Transcription Factors
- RNA Splicing
- Epigenetics
- DNA Methylation
- DNA Demethylation
- Euchromatin and Heterochromatin
All 39 lessons in Gene Expression · All Edexcel A-level Biology topics