Concept 1 / 9
Central Dogma & Its Exceptions
Classical central dogma: information flows in one direction:
DNA --(transcription)--> RNA --(translation)--> ProteinThe slides stress the dogma is obsolete — information flow is more complex:
- Reverse transcription: RNA -> DNA (e.g. retroviruses).
- DNA self-replication (the DNA->DNA loop).
- RNA that is never translated but still functional: scaffold RNA, ribozymes (catalytic RNA), and regulatory ncRNAs.
Codons are read in groups of 3 nucleotides on the mRNA (5'->3'); each codon specifies one amino acid in the growing polypeptide (e.g. UAC=Tyr, UCA=Ser, GGU=Gly).