MICB 201 Chapter Notes - Chapter 5: Magnetotaxis, Environmental Law, Correlation Does Not Imply Causation
Document Summary
5. 1 chemotaxis: def: movement towards/away from chemicals (behavioural change, attractants: usually nutrients, repellents: wastes/toxic chemicals, mostly studied in peritrichously flagellated e. coli, chemotaxis: change in behaviour using existing proteins, positive-towards attractants, negative-away from repellents. Early conclusions: organisms moves towards higher [attractant] if attractant concentration gradient is present. Magnetotactic bacteria = compass needle: most bacteria with magnetosome are microaerophiles (adapted to low o2) Environmentally-regulated gene expression: some proteins are only made under certain environments. Constitutive (house-keeping) gene expression: some proteins needed all the time (constitutively, ex: ribosomal proteins. Developmentally-regulated gene expression: as part of a developmental genetic program involving cellular differentiation, different proteins need to be made in particular order/ at different times, may be constitutive or linked to environmental conditions. In multicellular organisms, some proteins needed only in certain cell types: may be constitutive or linked to environmental conditions. Environmental regulation of genes encoding proteins for iron acquisition: most life requires iron.
