What are Viruses

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http://youtube.com/watch?v=wAWofEyH_r8

A short video explaining viruses and some fascinating facts about them, including the vast number of viruses, their incredibly small size, and how they work! • Transcript: • What are Viruses? • It is April, 2020 and we are in the midst of the COVID-19 pandemic, a worldwide disease caused by the novel coronavirus. In just a few short months, the world has been reminded of the HUGE impact that viruses can have. • So, what are viruses? • Viruses are infectious agents, parasites that need to infect a host cell in order to reproduce or carry out any functions. They are not cells and cannot do any of their own metabolism, so they are generally considered to be nonliving. • They are incredibly small, much smaller than even the smallest bacterial cell, with a common size of around 100 nanometers. That means that about 1 quadrillion (1015) viruses could fit in the volume of this marble I’m holding. • It is estimated that the number of viruses on earth is millions of times greater than the number of stars in the entire UNIVERSE and that all living things can be infected by some type of virus. • All viruses have some characteristics in common: • They always have genetic material in the form of a nucleic acid, either DNA or RNA. This is the instructions for how to build more viruses. • They also always have a protein coat called a capsid that encloses their genetic material, as well as other proteins that help them infect cells, such as viral enzymes, or spike proteins that help them gain entry. • Some also have a membrane on the outside called an envelope. • They come in a variety of shapes and sizes as you can see in these electron microscope images of some viruses. • How Viruses Work • Viruses hijack your cells and turn them into virus factories. They do this by inserting their genetic material and viral enzymes into your cell. Once inside, YOUR cell is tricked into following the instructions of the viral DNA or RNA to make more viral DNA or RNA and viral proteins. So, the virus uses your cell machinery to reproduce itself and pump out more viruses that can then spread by infecting other cells. • Sources and Credits: • Music: www.bensound.com • http://book.bionumbers.org/how-big-ar... for 100 nm size as common size for viruses and estimated number of viruses on earth as 10^31 • Microbiology by numbers. Nat Rev Microbiol 9, 628 (2011). https://doi.org/10.1038/nrmicro2644 also cites 10^31 as the estimated number of viruses on earth here: https://www.nature.com/articles/nrmic.... It also has may other interesting comparisons to give you an understanding of the vast number of viruses on earth. + • https://www.space.com/26078-how-many-... (source for estimated number of stars in the universe as 10^24). • https://www.scripps.edu/news-and-even... (Electron Microscope Picture of COVID-19 from Scripps Research) • Video of Rotating Earth by NASA-Imagery from Pixabay • Photo of workers in HazMat gear by Tedward Quinn on Unsplash • Photo of empty shelves by Richard Burlton on Unsplash • Photo of man with mask by Maiko Valentino on Unsplash • Pinwheel Galaxy image: https://en.wikipedia.org/wiki/Galaxy#... ESA/Hubble • Ebola Virus image from CDC • Influenza virus Photo Credit: Cynthia Goldsmith Content Providers(s): CDC/ Dr. Erskine. L. Palmer; Dr. M. L. Martin / Public domain https://commons.wikimedia.org/wiki/Fi... • Image of T4 bacteriophage from here: https://physicstoday.scitation.org/do...

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