Why Eukaryotic Cells Separate the Nucleus and Cytoplasm
- In eukaryotic cells, chromosomes are stored in the nucleus, which separates transcription and translation into two different compartments.
- This setup helps protect DNA and allows cells to regulate gene expression more effectively.
Protecting DNA
- Eukaryotic cells keep their DNA inside the nucleus, shielding it from enzymes and molecules in the cytoplasm that could damage it.
- Prokaryotic cells don’t have a nucleus, so their DNA and ribosomes are in the same space.
- This means transcription and translation happen at the same time, without any separation.
he nuclear envelope, a double membrane with pores, protects DNA and controls what enters or exits the nucleus.
HintThe nuclear envelope is a double membrane with nuclear pores that allow selective exchange of molecules, such as the export of mRNA or the import of proteins required for transcription.
How Transcription and Translation Are Separated
- In eukaryotes, transcription happens in the nucleus, where mRNA is made. The mRNA then moves to the cytoplasm through nuclear pores, where translation occurs.
- In prokaryotes, these processes happen together in the cytoplasm. As soon as mRNA is made, ribosomes start translating it into protein.
Post-Transcriptional Modification
- Eukaryotic cells process mRNA before it leaves the nucleus. This step is called post-transcriptional modification, and it includes:
- Capping: Adding a 5’ cap to stabilize the mRNA.
- Polyadenylation: Adding a poly-A tail to the 3’ end to protect it from breaking down.
- Splicing: Removing introns (non-coding regions) and joining exons (coding regions) to form a complete mRNA strand.
