Answer:
In eukaryotic cells, gene expression involves many steps and can be regulated at almost any of these steps. Here are the steps in gene expression and where they occur in a eukaryotic cell:
1. Epigenetic level: The first stage of gene expression control occurs at the epigenetic level. Epigenetic mechanisms control access to the chromosomal region to allow genes to be turned on or off.
2. Transcription: The next step is transcription, which occurs in the nucleus. During transcription, a molecule of RNA polymerase II binds to the transcription start site of a gene and transcribes it into RNA.
3. RNA processing: After transcription, the RNA transcripts are processed while still within the nucleus.
4. mRNA stability: The stability of messenger RNA (mRNA) molecules is regulated, which means that the rate at which they are degraded can be altered.
5. Translation: The final step is translation, which occurs in the cytoplasm. During translation, ribosomes translate the mRNA into a polypeptide. The efficiency with which ribosomes translate the mRNA can also be regulated.