Regulation of gene expression
1. What is an operon?
2. In general terms, how do transcriptional regulators regulate gene expression? What is the effect
of a repressor binding to DNA? What is the name of the DNA sequence where repressors bind?
What is the effect of an activator binding to the DNA?
3. Describe the function and regulation of the following operons:
- Ara operon (regulation by AraC and arabinose)
- Trp operon (regulation by the Trp repressor and tryptophan)
- Lac operon (regulation by the lac repressor and allolactose; regulation by CAP and cAMP)
4. What is the difference between an inducible and a repressible operon?
5. What are riboswitches? How can riboswitches influence gene expression?
6. what are the ways in which cells can hide the start codon from the ribosome?
7. Describe how transcription factors can turn genes on or off in eukaryotic cells. Include the
following in your description:
- Mediator Complex
- Histone Modifying Enzymes
- Chromatin Remodeling Complexes
- DNA Looping
8. What is DNA methylation? What is the effect of DNA methylation on gene expression? What is
the enzyme that methylates DNA?
9. What is RNAi? Describe how RNAi can lead to destruction of foreign RNA molecules. Include
the roles of dsRNA, Dicer and siRNAs in your description.