Viruses

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Virus Noun

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[vahy-ruhs]

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Virus

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A nonliving particle of proteins and nucleic acids that can only replicate by infecting a living host cell.

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Example: This diagram shows the main parts of a virus, including its genetic material (viral genome) protected by a protein coat (capsid) and an outer layer (envelope).

Front

Nucleic Acid Noun

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[noo-klee-ik as-id]

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Nucleic Acid

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The genetic material of an organism, like DNA or RNA, carrying instructions for its functions and found within viruses.

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Example: This diagram shows the three parts of a nucleotide—a phosphate, a sugar, and a base—combining to form the single unit that builds nucleic acids.

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Metabolism Noun

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[muh-tab-uh-liz-uhm]

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Metabolism

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The set of life-sustaining chemical reactions in organisms, which viruses lack and must obtain from a host cell.

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Example: This diagram shows cellular respiration, a key metabolic process where a cell uses glucose and oxygen to create energy (ATP), which viruses hijack to replicate.

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Parasite Noun

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[par-uh-sahyt]

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Parasite

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An organism that lives in or on a host, benefiting by deriving resources at the host's expense.

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Example: This diagram shows a tick, a type of parasite, attaching to different hosts like deer and humans to feed throughout its life cycle.

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Homeostasis Noun

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[hoh-mee-oh-stey-sis]

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Homeostasis

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The ability of an organism to maintain a stable internal environment, a characteristic of life that viruses do not possess.

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Example: The body maintains a stable internal state, like temperature, using a feedback loop to detect and correct imbalances, which is a process called homeostasis.

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Virion Noun

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[vahy-ree-on]

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Virion

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An individual, complete, and infectious virus particle that is found existing outside of a host cell.

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Example: A virion is a complete virus particle, shown here with its genetic material (nucleic acid) inside a protective protein head and a tail assembly.

Front

Capsid Noun

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[kap-sid]

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Capsid

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The protective protein coat that surrounds the nucleic acid, or genetic material, of a virus particle.

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Example: This diagram shows a virus's capsid, which is the protective protein shell that surrounds and encloses the virus's genetic material (like DNA).

Front

Envelope Noun

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[en-vuh-lohp]

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Envelope

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An outer membrane derived from the host's cell membrane that surrounds the capsid of some types of viruses.

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Example: This image shows the structure of an HIV virus, where the viral envelope is the outermost layer surrounding the capsid, containing glycoproteins.

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Antibiotics Noun

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[an-tee-bahy-ot-iks]

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Antibiotics

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Medicines that inhibit the growth of or destroy bacteria and are not effective against viral infections.

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Replicate Verb

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[rep-li-keyt]

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Replicate

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To make copies; viruses cannot replicate on their own and must use a host cell's machinery to do so.