Virus: a chromosome- like part surrounded by a protein coat.
Host: an organism that provides food for a parasite.
Parasite: an organism that lives in or on another living thing and gets food from it.
Interferon: a chemical substance that interferes with the way viruses reproduce.
Vaccine: a substance made from weakened or dead viruses that protects you against certain diseases.
Bacteria: very small, one-celled monerans
Colony: a group of similar cells growing next to each other that do not depend on each other.
Capsule: a sticky outer layer produced by bacteria.
Flagellum: a whiplike thread use for movement by bacteria.
Fission: the process of one organism dividing into two organisms.
Asexual reproduction: the reproducin of a living thing from only one parent.
Endospore: a thick-walled structure that forms inside a bacterial cell.
Saprophyte: organisms that use dead materials for food.
Descomposer: living things that get their food from breaking down dead matter into simpler chemicals.
Koch´s postulates: steps for proving that a disease is caused by a certain microscopic organisms.
Communicable disease: those that can be passed from one organisms to another.
Antibiotic: a chemical substance that kill or slow the growth of bacteria. 
Biotechnology: The use of living thing to solve pratical problems. 
Pasteurization: the process of heating milk to kill harmful bacteria.
Blue-green bacteria: small, one-celled monerans that contain chlorophyll and can make their own food.