trp operon can run even in the presence of repressor. The attenuation system permits another 10-fold control over the operon’s activity. 

Thus, the combination of repression and attenuation controls the operon over a 700-fold range, from fully inactive to fully active: (70-fold [repression] X 10-fold [attenuation] = 700-fold). 

#Id: 5102

#Unit 6. System Physiology – Plant

A protein kinase (CK2)CKB3 can interact with and phosphorylate CCA1, which is a multisubunit protein with serine/threonine kinase activity.

#Id: 9408

#Unit 11. Evolution and Behavior

Group Living Has Advantages and Disadvantages

When animals live together in groups such as flocks or herds

Disadvantage- Group promote competition for food and increased transmission of parasites and other diseases.

Advantage - Benefits relate to group defense against predators through increased vigilance and through protection in numbers.

#Id: 516

#Unit 2. Cellular Organization

Escherichia coli K-12 is 4.6Mb genome with 4400 genes so gene density 950 genes/Mb.

#Id: 10389

#Unit 4. Cell Communication and Cell Signaling

Class II, but not class I, presentation is inhibited by treatment of the cells with an agent that blocks endocytic processing within the cell (chloroquine).

#Id: 8136

#Unit 2. Cellular Organization

Golgi apparatus is a major site of carbohydrate synthesis, as well as a sorting and dispatching station for proteins products.