Antigens can be defined as molecules that can bind to antibodies. Many authors prefer to define it as any substance capable of eliciting a response from the immune system, however there are antigenic substances that react with the antibody but are not able to stimulate its production.
Antigens are usually unknown molecules in the body. Molecules that detach from foreign cells such as bacteria, fungi, protozoa or even viruses can be considered antigens. Toxins released by bacteria are also examples of substances that can bind to antibodies.
When an individual's blood-type alleles have instructions that direct the construction of a specific set of chemicals that protrude from all red blood cells, these chemicals are the antigens.
When an earthquake occurs energy is transferred, from where the rocks break, and travels throughout the world. The bigger the quake the further from the epicentre the waves will travel. There are two types of earthquake wave generated during an earth quake. They carry energy away from the earthquake epicentre.
