Use this helpful guide to understand terms commonly used in research investigating viruses and their hosts.

• Cyanobacteria (used in Week 1, Week 2) – A lineage of bacteria that conduct photosynthesis to grow, like plants. Cyano- comes from the color of the pigments they use to gather light energy. Cyanobacteria live in all kinds of environments from the ocean, freshwater, the symbiotic partner of lichens, even to deserts.

• Cyanophage (used in Week 1) – A type of virus that specifically infects cyanobacteria.

• Host (used in Week 1) – The organism that a particular virus infects, not necessarily a human.

• Nucleotide (used in Week 1) – A type of biological molecule that carries the information in DNA and RNA. The order in which nucleotides appear in a particular DNA sequence determines what proteins that DNA tells a cell to make.

• Metagenome (used in Week 2) – An approach to DNA sequencing that attempts to sequence the genomes of every type of organism in a given environment/sample (‘meta’ referring to the genome comprised of all of the genomes of the individual microorganisms living in the ecosystem). A popular technique in environmental microbiology, where separating different kinds of organisms to sequence individually is either difficult or irrelevant to the question at hand.

• Nutrient stress (used in Week 2) – A physiological state an organism goes through in response to a shortage of nutrients (nitrogen, phosphorus, iron) in the surrounding environment.

• Phytoplankton (used in Week 2) – Small organisms living in water that can photosynthesize.

• Primary producers (used in Week 2) – Organisms that create food through photosynthesis, turning carbon dioxide into sugars and starches. The grass on a lawn is an example.

• Virus (used in Week 1) – A type of biological entity. Viruses are parasites with genetic information (either DNA or RNA genomes) that need help from a particular organism (host) in order to reproduce (obligate intracellular parasites). Many viruses package genetic information inside of protein coats for protection while they are outside of their host. There are many different kinds of viruses with many different kinds of hosts, from the viruses we know that infect us as humans, to viruses that infect the bacteria that make us sick (viruses aren’t all bad!) Lots of viruses that are completely benign to humans exist in environments like soil, lakes, even hydrothermal vents at the bottom of the ocean.

• Zooplankton (used in Week 3) – A type of biological entity. Animals that are typically microscopic that drift in bodies of water and feed on phytoplankton. Zooplankton are an important part of the marine food web, and are the animal counterpart to phytoplankton.