Central Dogma of Biology
The Central Dogma of Molecular Biology, formulated by Francis Crick in 1958, describes the general flow of genetic information within a biological system: DNA is transcribed into RNA, and RNA is translated into protein. Crick's original statement also specified that information transfer from protein back to nucleic acid does not normally occur, establishing a directional framework for gene expression. The discovery of reverse transcriptase in retroviruses revealed that RNA can also be reverse-transcribed into DNA, representing a known exception to the standard flow while still consistent with Crick's framework.
Key Formula
DNA → RNA → Protein (via transcription then translation)
LaTeX: \text{DNA} \xrightarrow{\text{Transcription}} \text{RNA} \xrightarrow{\text{Translation}} \text{Protein}
| Symbol | Meaning | Unit |
|---|---|---|
| DNA | Deoxyribonucleic acid — the information store | base pairs (bp) |
| RNA | Ribonucleic acid — the messenger intermediate | nucleotides (nt) |
| Protein | Polypeptide chain — the functional product | amino acids (aa) |
Information Transfers in the Central Dogma
| Transfer | Direction | Enzyme | Normal / Special |
|---|---|---|---|
| DNA → DNA | Replication | DNA polymerase | Normal (universal) |
| DNA → RNA | Transcription | RNA polymerase | Normal (universal) |
| RNA → Protein | Translation | Ribosome + tRNA | Normal (universal) |
| RNA → DNA | Reverse transcription | Reverse transcriptase | Special (retroviruses) |
| RNA → RNA | RNA replication | RNA-dependent RNA polymerase | Special (RNA viruses) |
| Protein → Nucleic acid | Direct information transfer | None known | Never observed |
Interactive Tools
Khan Academy — Central Dogma
Video series covering transcription, translation, and the central dogma
Open ToolNCBI — Molecular Biology Resources
NCBI portal for gene expression and molecular biology data
Open ToolBrilliant.org — Molecular Biology
Interactive problem-solving course covering central dogma and gene expression
Open Tool
Wikimedia Commons, CC BY-SA
Related Terms
Reverse Transcriptase
Reverse transcriptase (RT) is an RNA-dependent DNA polymerase enzyme that synthesises a complementary DNA (cDNA) strand using an RNA template, a process called reverse transcription that is the reverse of the normal transcription step in the central dogma. It was discovered independently by Howard Temin and David Baltimore in 1970, a finding that won them the Nobel Prize in Physiology or Medicine in 1975 and fundamentally altered the understanding of genetic information flow. Reverse transcriptase is encoded by retroviruses (including HIV) and retrotransposons, and is an essential biotechnology tool used to create cDNA libraries for cloning, gene expression analysis, and RT-PCR diagnostics.
Alternative Splicing
Alternative splicing is a regulated process during gene expression in which particular exons of a pre-mRNA transcript are included or excluded to generate multiple distinct mature mRNA isoforms from a single gene. This mechanism dramatically expands proteomic diversity; estimates suggest that over 95% of human multi-exon genes undergo alternative splicing, allowing a genome of ~20,000 genes to produce hundreds of thousands of protein variants. Mis-regulation of alternative splicing is implicated in many diseases including spinal muscular atrophy, various cancers, and neurological disorders.
Transcription Factor
A transcription factor is a protein that binds to specific DNA sequences in the promoter or enhancer regions of a gene to control the rate of transcription by RNA polymerase. These proteins act as molecular switches, either activating or repressing gene expression in response to developmental cues, environmental signals, or cellular needs. In humans, approximately 1,600 transcription factors have been identified, and their dysregulation is linked to cancers, developmental disorders, and metabolic diseases.
Named and described by Francis Crick in a 1958 lecture at the Society for Experimental Biology. "Dogma" was used in Crick's own words partly tongue-in-cheek, acknowledging it was an untested assumption at the time; "central" reflects its fundamental importance to all of molecular biology.