How does a protein kinase cascade work? what does it do to the original signal?

A protein kinase is an enzyme which catalysis the phosphorylation reaction.

The phosphorylation can either activate or deactivate other proteins or receptors.

A protein kinase cascade refers to the series of events in which a chain reaction of phosphorylation takes place by which thousands of proteins are phosphorylated.

It helps in signal transduction through which signals (usually hormone) from outside the cell are amplified and transferred to the target molecule present inside the cell.

For example, tyrosine kinase cascade.

desert perennials often survive by remaining dormant during dry periods of the year, then springing to life when water becomes available. most annual desert plants germinate only after heavy seasonal rain, then complete their reproductive cycle very quickly.