The Central Dogma in eukaryotic cells  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 © 1996 by Griffiths et al. ; text © 2008 by Steven M.
Carr