Virus modeaccessoires

Register Log in. Virus replication Download Virus replication. Download Virus replication. Bitesize category Pathogens and Disease. Related Articles Candida albicans. Aspergillus fumigatus. Chronic Obstructive Pulmonary Disease. Viruses versus vaccines: the economics of herd immunity. Biofilms and their role in pathogenesis. Virus replication. Viruses: Introduction. Ulcerative colitis and Trichuris infection. Often, they kill the host cell in the process, and cause damage to the host organism.

Viruses have been found everywhere on Earth. Researchers estimate that viruses outnumber bacteria by 10 to 1. Viruses are submicroscopic, which means that you cannot see them in the microscope. What's interesting about viruses is that they have two or three components. Starting from the inside, you will have a nucleic acid, which can be either RNA or DNA, and in both cases the nucleic acid can be either single-stranded or double-stranded.

For information on user permissions, please read our Terms of Service. If you have questions about how to cite anything on our website in your project or classroom presentation, please contact your teacher. They will best know the preferred format.

When you reach out to them, you will need the page title, URL, and the date you accessed the resource. If a media asset is downloadable, a download button appears in the corner of the media viewer. If no button appears, you cannot download or save the media. Text on this page is printable and can be used according to our Terms of Service.

Any interactives on this page can only be played while you are visiting our website. You cannot download interactives. People get sick when another organism, big or small, invades their body and infects them. These infectious agents come in all shapes and sizes, and all of them pose different threats to the human body. Some are microscopic, such as bacteria or viruses, which attack human bodies on the cellular level.

Others are larger, like fungi, which are unicellular or multicellular organisms that grow on and feed off organic material, including humans. Finally, parasites such as tapeworms can find their way inside the human body and feed on blood and nutrients without killing their host. Learn more about infectious agents and their impact on human health with this curated resource collection.

Even the most basic parts of a cell can enable complex cellular processes, and multifunctional organelles expand these capabilities to make advanced activities possible for higher life-forms. Organelles are specialized structures that perform various tasks inside cells. Join our community of educators and receive the latest information on National Geographic's resources for you and your students. Skip to content. Image virus Viruses are microscopic biological agents that invade living hosts and infect their bodies by reproducing within their cell tissue.

Photograph by Maryna Olyak. Twitter Facebook Pinterest Google Classroom. Encyclopedic Entry Vocabulary. Some of these drugs stop DNA synthesis, preventing the virus from replicating Although viruses can have devastating health consequences, they also have important technological applications.