The Central
Dogma in prokaryotic versus eukaryotic cells
In prokaryotes (organisms without a nuclear
membrane), DNA undergoes replication and
transcription and RNA undergoes translation in an
undivided cell. 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.
In eukaryotes, 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.