Housekeeping genes are genes that code for enzymes and proteins that are constantly needed for the normal functioning of the cells and are constitutively expressed. Hormones such as growth hormones are only needed at specific times for a short period of time. Genes need to be turned on and off and the production of proteins needs to be upregulated and downregulated depending on demand. Regulation in both prokaryotes and eukaryotes may be:
- Transcriptional - stopping or starting transcription
- Post-transcriptional - modifying mRNA
- Translational - stopping or starting translation.
- Post-translational - modifying the protein to alter its function.
