Birgid Schlindwein's
Hypermedia Glossary Of Genetic Terms
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Birgid Schlindwein'sHypermedia Glossary Of Genetic TermsSearch Results |
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| Polymerase chain reaction (PCR) | A method, developed by Kary Banks Mullis 1983, for amplifying a DNA base sequence using a heat-stable polymerase and two 20-base primers, one complementary to the (+)-strand at one end of the sequence to be amplified and the other complementary to the (-)-strand at the other end. Because the newly synthesized DNA strands can subsequently serve as additional templates for the same primer sequences, successive rounds of primer annealing, strand elongation, and dissociation produce rapid and highly specific amplification of the desired sequence. PCR also can be used to detect the existence of the defined sequence in a DNA sample (see DNA amplification fingerprinting. Several variations have been developed for specific needs. May be combined with reverse transcription of mRNA to cDNA to amplify an mRNA so called RT-PCR. |
| Base sequence | The order of nucleotide bases in a DNA molecule. Length is usually defined as the number of base pairs. Cf. sequence, DNA sequence. |
| DNA polymerase | Enzymes that catalyze the synthesis of nucleic acids on preexisting nucleic acid templates, assembling DNA from deoxyribonucleotides. Cf. RNA polymerase. |
| Primer | Short preexisting single-stranded polynucleotide chain to which new deoxyribonucleotides can be added by DNA polymerase. It anneals to a nucleic acid template and promotes copying of the template starting from the primer site. |
| Complementary DNA (cDNA) | DNA that is synthesized from a messenger RNA template that corresponds to expressed sequences of genomic DNA. The term complementary DNA also may refer to DNA that is complementary to a particular DNA sequence. The single-stranded form is often used as a probe in physical mapping. |
| Strand | It is customary in genetics to use strand for chromatid. It has therefore been used in that sense in some books, where it has also been used for one double-chain (that is, duplex) DNA molecule. Chain, but not strand, has been used for a single polynucleotide. |
| DNA amplification fingerprinting (DAF) | A technique for amplifying anonymous streches of DNA using PCR. Related to RAPD. |
| Transcription | The synthesis of an RNA copy from a sequence of DNA (a gene); the first step in gene expression. Compare translation. |
| Messenger RNA (mRNA) | RNA that serves as a template for protein synthesis or for synthesis of cDNA. See genetic code. |
| Complementary DNA (cDNA) | DNA that is synthesized from a messenger RNA template that corresponds to expressed sequences of genomic DNA. The term complementary DNA also may refer to DNA that is complementary to a particular DNA sequence. The single-stranded form is often used as a probe in physical mapping. |