Molecular biology: transcription, translation, regulation of gene expression
Biochemistry · MBBS
DNA double helix
Interactive 3DThe twisted ladder of life — A–T and G–C base pairs winding 10 per turn.
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Study notes
Lactose in the gut switches on E. coli's lac operon within minutes. The classic operon: without lactose, a repressor blocks the genes for lactose-digesting enzymes; lactose inactivates the repressor — RNA polymerase transcribes, enzymes appear, lactose is digested. It is regulation's textbook — genes switched by need, not always on. Human regulation is grander (transcription factors, enhancers, chromatin, methylation) but the principle holds: expression follows demand, and its failure causes disease — from thalassemia (globin regulation) to cancer (oncogene activation).
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