Escerichia Coli bacteria can synthesis 3000 polypeptides but there is varioation in the number of polupeptides within the cell - there may be 10,000 ribosomal polypeptides and just 10 molecules of some regulatory proteins. Enzymes involved in basic cellular function are synthesised at a fairly constant rate.
Inducible enzymes are synthesised as varying rates according to the cell's circumstances. Bacteria produce enzymes to metabolise certain nutrients only when those nutrients are present. E. Coli normally respire glucose but can use lactose as a respiratory substrate
E. Coli grown in a cultuire medium with no lasctose are placed ina medium with lactos. At first they cannot metabolise lactose as three are only tiny anouts of the two enzymes needed to metabolise it - Beta-Galatosidase - catalyses hydrolysis of lactose into glucose and glatactose. - Lactose permease - transports lactose into the cell.
After a few minutes, E. Coli bacteria increase the rate of synthesis fo these enzymes by aobut 1000 times - Lactose triggers the production of the two enzymes and so is an inducer
Comments
No comments have yet been made