Gene regulation in prokaryotes
Readings
[edit | edit source]- Study guide:
- Wikipedia article: Operon
- Wikipedia article: The Lac Operon
- Wikipedia article: The Arabinose Operon
- Wikipedia article: The Tryptophan Operon
Gene regulation in prokaryotes
[edit | edit source]Constitutive vs Adaptive Enzymes
[edit | edit source]Genes for constitutive enzymes are always on and the gene is always produced. Adaptive genes may be either inducible (generally off; may be turned on) or repressible (generally on; may be turned off).
Adaptive enzymes
[edit | edit source]Inducible Genes are generally enzymes necessary for catabolism and are only turned on if substrate is present as the substrate acts an inducer (effector).
- e.g. The lac operon, The ara operon
Repressible Genes are generally enzymes involved in anabolism and are inhibited by feedback (the end product acts as a repressor for the gene)
- e.g. Trp operon
Operons
[edit | edit source]An operon is a group of genes that are coregulated. These genes usually have related function and are often cotranscribed as a single mRNA strand. Such an RNA strand is called a Polycistronic RNA