Control of Gene expression

• The promoter region is the site where RNA polymerase binds to initiate transcription.
• Prokaryotic operons are multiple prokaryotic genes that share a promoter and are transcribed together.
• Post-transcriptional control is a type of gene regulation that occurs after transcription but before translation.
• Post-transcriptional control can involve regulation through post-translational modification, where proteins can be modified or degraded after translation.
• Negative control = regulatory protein is a repressor, inhibiting gene expression.
• Eukaryotes can regulate transcription by modifying DNA and/or histone protein tails, which alters chromatin structure.
• RNA stability is a post-transcriptional control where 5’ cap and 3’ tail can be removed to increase degradation, which is degradation is done through small regulatory RNAs (siRNA) and microRNAs (miRNA).
• Transcription factor proteins are needed to initiate transcription in eukaryotes.
• Alternative splicing and RNA editing can lead to the production of different proteins in different cells.
• Small regulatory RNAs (miRNAs and siRNAs) can block translation.
• mRNA can be degraded by small regulatory RNAs (siRNA) and microRNAs (miRNA).
• Proteins can activate or block translation initiation.
• The Lac operon is transcribed (on) when glucose is absent and not transcribed (off) when glucose is present.
• The activator protein stimulates the binding of RNA polymerase.
• Transcription factor proteins are needed to start transcription in eukaryotes.
• Positive control = regulatory protein is an activator, stimulating gene expression.
• When a cell needs the proteins to digest lactose, it is in a negative control state.
• When glucose is absent, the cell is in a positive control state.