iGen3 05-09

The Central Dogma in prokaryotic vs eukaryotic cells

In prokaryotes (organisms without a nuclear membrane), DNA undergoes replication and transcription and RNA undergoes translation in an undivided compartment. All three processes can occur simultaneously.

In eukaryotes (organisms with a nuclear membrane), DNA undergoes replication and transcription in the nucleus, and proteins are made in the cytoplasm. RNA must therefore travel across the nuclear membrane before it undergoes translation. This means that  transcription and translation are physically separated. The primary transcript, heterogeneous nuclear RNA (hnRNA), undergoes extensive post-transcriptional processing to make a messenger RNA (mRNA)molecule that can pass through the nuclear membrane.


Figure © 2010 PJ Russell, iGenetics 3rd ed.; all text material © 2010 by Steven M. Carr