BISC 121Lg Lecture Notes - Lecture 22: Magnetotaxis, Chemotaxis, Complex Cell
Document Summary
Lecture 22: 1) gene that it controls, 2) promoter regions where rna polymerase bonds, 3) operon on/off switch. Must be on for polymerase to bond. Binding by a repressor to an operator is reversible. Many repressors have allosteric sites that change shape. Repressible operons are inhibited by a specific small molecule bonding allosterically to a receptor. Inducible operon is the opposite (lac operon is off until lactose is present) Repressible enzymes usually function in anabolic pathways. Degree of operon transcription can be controlled by other substance. I(cid:374) la(cid:272) opero(cid:374), la(cid:272)tose deter(cid:373)i(cid:374)es o(cid:374) a(cid:374)d off (cid:271)ut glu(cid:272)ose (cid:272)o(cid:374)trols the (cid:862)volu(cid:373)e(cid:863) Prokaryotes- early organisms and still dominate the biosphere: live in all habitats, tiny minority cause human disease. The plague, cholera, stds, tb: most are benign or beneficial. Millions of prokaryote species, only about 10,000 are named. It"s hard to figure out how to define prokaryotes.
