We usually think of communication as involving words or gestures. In fact, chemicals are used by both animals and plants to communicate all the time.
What Are Chemical Messages?
Chemicals usually carry messages from one part to another within the same plant or animal, but when you get a sudden scare, your mind sends a chemical message to the heart telling it to speed up.
Other chemicals cause hair to start growing when a child reaches a certain age. Pheromones, chemicals given off by some animals to attract mates, are examples of chemical messages that work between individuals.
Most Chemical Messages Take The Form Of Protein
One reason is that protein molecules occur in an almost endless variety of forms, each with slightly different properties.
And, just as you can express more ideas with a larger vocabulary, a plant or animal can send more messages with a larger variety of chemicals. But, like other sorts of communication, the protein message has to be received as well as sent.
When one of these messages reaches its destination, the protein interacts with a unique receptor sitein the heart, the hair follicle, or in whatever organ it was sent to.
In many cases, a messenger-protein and a receptor have evolved together and only interact with each other. In other cases, several proteins can interact with the same receptor to produce the same effect.
Next time we'll look at how plants send out protein messages with their pollen to help identify other plants of the same species, and how the same messages produce a runny nose in some people.