Microbiologi 7
Enzyme repression vs enzyme induction
Enzyme repression is the final product of biosynthetic pathway represses the enzymes of the process. Often anabolic enzymes for example aginine- operon.
Enzyme induction is an enzyme that is made when only its substrate is present. Often catabolic enzymes for example lactose- operon. In E.coli it is orchestrated by mal regulation
Maltose- catabolism
It involves the enzymatic breakdown of maltose that is a disaccharide composed of two glucose molecules linked by an 1-4 alpha glycosidic bond into glucose units that can be utilized for energy production
Diauxic growth of E. Coli
It can come as a consequence of catabolic repression. It leads to two exponential growth phases. If two usable energy sources are available, the cells first consume the better one. The growth stops when the better source is depleted. The growth on glucose increase fast and then a lag phase will come when the glucose is exhausted and the growth will stop. Then the E. coli resumes growth using lactose but not as fast as before.
Two component system
It is a common signal transduction mechansim in bacteria that helps them sense and response to their environment. it contains of two main proteins, sensor kinase and response recollection. The EnvZ- OmpR system regulated osmolarity is high, EnvZ is a sensor kinase and detects changes in osmolarity, if the osmolarity is high, the EnvZ phosphorylates OmpR. OmpR is the response regulator and regulates the expression of OmpF and OmpC genes, which control outer membrane porins to adjust permeability.
Quorom- sensing
A cell to cell comminication system used by bacteria to coordinate group behaviors based on population density. It consists of three main proteins, signal molecules, sensor kinase and response regulation