Answer:
chemical change.
Explanation:
There are two types of changes in matter: physical change and chemical change.
physical change- it is a change in matter that alters only its physical properties or its physical appearance. This type of change is reversible. For example- freezing of water, the water turns into solid ice and it can be reversed by melting the ice.
chemical change- it is a change in matter that alter its chemical and thus its physical properties. Most chemical changes are irreversible. for example- burning of paper, results in black soot and ashes- Thus changing both physical and chemical properties.
The point at which the toxin would interrupt normal cell signalling in the pathway is the signal amplification.
This is because of the G-protein uncoupling and inhibition of signal amplification by pertusis toxin. Pertusis toxin released by the bacteria Bordetella pertusis and prevents signal that is amplifying from the protein. The G-protein coordinates the interaction between membrane bound receptor proteins and the effector proteins involved in the intracellular signalling. The toxin promotes the uncoupling of this heterotrimetric protein and also inhibits the amplification thus preventing the interaction of the receptor proteins and the second messengers.
