what is probe in biotechnology

In biotechnology, a probe is a single-stranded sequence of DNA or RNA that is used to search for its complementary sequence in a sample genome. The probe is placed into contact with the sample under conditions that allow the probe sequence to hybridize with its complementary sequence. The probe is labeled with a radioactive or chemical tag that allows its binding to be visualized. Probes can be used to screen the genome to find out if there are extra copies or missing copies of certain parts of the genome, which happens in hereditary syndromes and in cancers. Probes are also used in a number of clinical genomic tests, including fluorescent in situ hybridization, quantitative PCR, and microarrays. Both RNA and DNA can be used as probes, but single-stranded DNA probes are more convenient and preferable. RNA probes are stretches of single-stranded RNA used to detect the presence of complementary nucleic acid sequences (target sequences) by hybridization.