The major function of the immune system is to protect the host from environmental agents such as microbes or chemicals, thereby preserving the integrity of the body. This is done by the recognition of self and response to non-self.
Cohesion is the property of like molecules to stick to each when they have a mutual attraction
Adhesion is the property of different molecules or surfaces to stick to each other
DNA (or deoxyribonucleic acid) is the molecule that carries the genetic information in all cellular forms of life and some viruses. It belongs to a class of molecules called the nucleic acids, which are polynucleotides - that is, long chains of nucleotides.
