Viruses

Biology of Viruses Structure of Viruses: Size -Less then 0.2 microns Parts of the Virus 1)Capsid: -Made of protein subunits 2) Inner core: made of a double or single strand of nucleic acids (DNA and RNA) 3) Envelope: -A lipid membrane that surrounds the virus. 4) Spikes: -Glycoproteins found on the outer side of the envelope

Virus Anatomy

Viral Reproduction Viral Reproduction: Every virus has a specific host that it needs for reproduction. Eg. Bacteriophage: A virus that infects bacteria Eg 2. Different strains of the flu virus infect different types of animals (Bird flu)

How do viruses detect their host Detecting the host: Every cell has a chemical marker on its surface. The spike on the virus surface will only bond to the chemical marker on the right host cell

Life Cycle of an RNA Virus 1)Attachment (a): Virus spikes bind to the surface receptor of its host cell (Also known as hijacking) 2)Entry (b): Envelope of the virus binds to the cell membrane of the host. Once fused the virus releases its contents into the cell.

Life Cycle of an RNA Virus 3) Replication: Virus makes complementary copies of its RNA. 4) Biosynthesis (c): mRNA produces more capsids and spike proteins using the host’s ribosomes

Life Cycle of an RNA Virus 5)Assembly (d): The newly synthesized parts are put together creating new viruses. 6)Budding (e): New viruses are released by pinching off the membrane of the host cell with the contents of the new virus inside of it

Latency Latency: Some viruses remain undetected inside the host cell for a period of time. This hidden period of time is called latency During the latent period the virus replicates its genome (genetic material) but does not produce new viruses.

Latency Latency: Some viruses remain undetected inside the host cell for a period of time. This hidden period of time is called latency During the latent period the virus replicates its genome (genetic material) but does not produce new viruses. Triggering Biosynthesis in a Latent Virus: Environmental factors can trigger biosynthesis in latent virus. Triggers include UV radiation or a change in temperature