In Genetics, What Is Complementary DNA?
A double-stranded DNA molecule constituting a gene uses a single strand as a template, and is transcribed to generate a messenger RNA molecule complementary to its sequence. Then, under the action of reverse transcriptase, a single-stranded DNA complementary to the mRNA sequence is synthesized using the mRNA molecule as a template. And finally use the single-stranded DNA as a template to synthesize another complementary single-stranded DNA
Complementary DNA
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- Chinese name
- Complementary DNA
- Foreign name
- cDNA, complementary DNA
- Subject Classification
- Genetics
- Notes
- Double-stranded DNA copies of messenger RNA molecules
- A double-stranded DNA molecule constituting a gene uses a single strand as a template, and is transcribed to generate a messenger RNA molecule complementary to its sequence. Then, under the action of reverse transcriptase, a single-stranded DNA complementary to the mRNA sequence is synthesized using the mRNA molecule as a template. And finally use the single-stranded DNA as a template to synthesize another complementary single-stranded DNA
- Two complementary single-stranded DNA molecules make up a double-stranded cDNA molecule. Therefore, the sequence of the double-stranded cDNA molecule is the same as the gene of the mRNA molecule produced by transcription. So a cDNA molecule represents a gene. However, cDNA is still different from the gene Because when the gene is transcribed to produce mRNA, some non-coding sequences, i.e., introns, are deleted, and only the coding sequences, i.e., exons, are retained. Therefore, the cDNA sequences are much shorter than the gene sequences, because the cDNA does not include Non-coding sequences of genes --- introns.