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[Biochemistry](https://durgical.com/en/biochemistry/) · Topic

# Central dogma of molecular biology

Information flows from DNA to RNA and from RNA to protein; replication copies DNA and reverse transcription goes back from RNA to DNA.

Updated 2026-11-01

## Key facts

- Replication: DNA → DNA (S phase). Transcription: DNA → RNA (nucleus). Translation: messenger RNA → protein (cytoplasmic ribosomes).
- Classic exception: reverse transcriptase copies RNA into DNA (retroviruses such as HIV, and telomerase).
- Some RNA viruses copy RNA into RNA with an RNA-dependent RNA polymerase.
- One gene can give many proteins thanks to alternative splicing; not every gene ends in a protein (tRNA, rRNA, microRNA).

## In detail

- Scheme (not a metabolic pathway): DNA —replication→ DNA; DNA —transcription→ pre-mRNA —processing→ mRNA —translation→ protein —folding and modification→ active protein.
- In eukaryotic cells transcription and translation happen in separate compartments: the mRNA must mature (cap, poly-A tail, splicing) and leave through the nuclear pores.
- Bacteria have no nucleus: the ribosome starts translating the mRNA while it is still being transcribed (coupling).
- Each step has quality control: DNA polymerase proofreading, nonsense-mediated decay (NMD) of mRNAs with premature stop codons, and chaperones plus the proteasome for misfolded proteins.
- Each step is a drug target: fluoroquinolones (bacterial replication), rifampicin (bacterial transcription), aminoglycosides, macrolides and tetracyclines (bacterial translation), nucleoside analogues (HIV reverse transcriptase).

## Clinical notes

- Reverse transcriptase inhibitors block HIV's RNA → DNA step, which human cells do not use for their own genes.
- mRNA vaccines deliver a message that ribosomes translate into an antigenic protein, without entering the nucleus or changing the DNA.

## Related conditions

- [HIV infection and AIDS](https://durgical.com/en/conditions/hiv-infection-and-aids/)

## Related

- [DNA structure and chromatin](https://durgical.com/en/biochemistry/topics/dna-structure-and-chromatin/)
- [DNA replication: the replication fork](https://durgical.com/en/biochemistry/topics/dna-replication-the-replication-fork/)
- [Transcription](https://durgical.com/en/biochemistry/topics/transcription/)
- [RNA processing (cap, poly-A tail and splicing)](https://durgical.com/en/biochemistry/topics/rna-processing/)
- [Translation and the genetic code](https://durgical.com/en/biochemistry/topics/translation-and-the-genetic-code/)
- [Telomerase](https://durgical.com/en/biochemistry/enzymes/telomerase/)

## Test yourself

Think of the answer, then tap the question to see it.

## Which enzyme breaks the usual direction of the central dogma, and in which virus is it typical?

Reverse transcriptase, which copies RNA into DNA; it is typical of retroviruses such as HIV.

## Why can translation start before transcription ends in bacteria?

They have no nucleus: the mRNA stays in the cytoplasm and ribosomes translate it while it is being made.

## Which human enzyme is a reverse transcriptase?

Telomerase: it uses its own RNA as a template to lengthen telomeres.

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Educational information, not medical advice. For any symptom, see a health professional.

Sources: [Central Dogma](https://www.genome.gov/genetics-glossary/Central-Dogma) (National Human Genome Research Institute (NHGRI), 2026); [How do genes direct the production of proteins?: MedlinePlus Genetics](https://medlineplus.gov/genetics/understanding/howgeneswork/makingprotein/) (MedlinePlus, US National Library of Medicine, 2026); [Gene expression (Transcription)](https://reactome.org/PathwayBrowser/#/R-HSA-74160) (Reactome, 2026); Textbook of Biochemistry for Medical Students, 6th ed. (Jaypee Brothers Medical Publishers (Vasudevan DM, Sreekumari S, Vaidyanathan K), 2011).

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