#16 Transcription and Translation in Cells

In a prokaryotic cell, transcription and translation are coupled; that is, translation begins while the mRNA is still being synthesized. In a eukaryotic cell, transcription occurs in the nucleus, and translation occurs in the cytoplasm.

Prokaryotic Cell

Because there is no nucleus to separate the processes of transcription and translation, when bacterial genes are transcribed, their transcripts can immediately be translated.

Eukaryotic Cell

Transcription and translation are spatially and temporally separated in eukaryotic cells; that is, transcription occurs in the nucleus to produce a pre-mRNA molecule.

The pre-mRNA is typically processed to produce the mature mRNA, which exits the nucleus and is translated in the cytoplasm.

Eukaryotes

2. Transcription and translation of most eukaryotes are spatially separated.
3. Multiple RNA polyermases.
4. Transcription factor directly binds to the DNA template, but not to the RNA pol.
5. Requires ATP for initiation.
6. Nucleosome / chromatin.

Prokaryotes

1. Polycistronic mRNA.
2.  Coupling transcription and translation.
3. Single RNA polyermase
4. RNA pol holoenzyme itself, by associated sigma factor.
5. No ATP
6. Naked DNA

Most mRNAs are monocistronic(generally one gene for one protein)

I. Eukaryotes vs prokaryotes transcription.