1 / 17

Viruses

Viruses. Chapter 24. Virus. A nonliving particle made up of nucleic acid and a protein coat or nucleic acid and a lipid-protein coat. Scientists began studying viruses in the late 1800’s after they found that a factor smaller than a bacteria could cause disease. Characteristics of Viruses.

sol
Download Presentation

Viruses

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Viruses Chapter 24

  2. Virus • A nonliving particle made up of nucleic acid and a protein coat or nucleic acid and a lipid-protein coat. • Scientists began studying viruses in the late 1800’s after they found that a factor smaller than a bacteria could cause disease.

  3. Characteristics of Viruses • Do NOT have cytoplasm or organelles • Cannot carry out cellular function such as metabolism and homeostasis • Cannot reproduce outside their host cell

  4. Characteristics of Virusescontinued • Obligate intracellular parasites

  5. Characteristics of Virusescontinued • Capsid – a protein coat is the only layer surrounding some viruses • Some viruses have a bilipid membrane called an envelope that surrounds the capsid http://www.odec.ca/projects/2004/lija4j0/public_html/img/virus.jpg

  6. Characteristics of Virusescontinued • Viruses can be classified by whether they have RNA or DNA, single or double stranded, linear or circular, and based on the nature of their capsid and on the presence or absence of an envelope. • Viruses need to recognize a host cell before they can infect it

  7. Lytic Cycle • During this cycle a virus invades a host cell, produces new viruses, and ruptures (lyses) the host cell when releasing newly formed viruses. • Viruses that reproduce only by the lytic cycle are called virulent.

  8. Lytic Cycle • 1. Virus attaches to the host cell and injects its DNA • 2. The viral DNA circularizes(organizes) • 3. Viral DNA takes control of the cell • 4. New viruses are made • 5. The cell lyses, releasing more viruses

  9. Lysogenic Cycle • Allows viruses to hide in their host cell for days, months, or years. • A virus whose replication includes the lysogenic cycle is called a temperate virus

  10. Lysogenic Cycle • 1. Will exit the Lytic cycle. • 2. Viral DNA will become part of the host cell DNA. • 3. Host cell will make copies of itself • 4. Will then re-enter the lytic cycle when it becomes activated

  11. Origin of Viruses • Most scientists reason that viruses evolved from early cells. https://www.jyu.fi/bioenv/en/divisions/smb/virus/astrovirology/alkukuvia.jpg

  12. Viral Diseases Section 24.2

  13. Vector • an intermediate host that transfers a pathogen or parasite to another organisms. Include: humans, animals, mosquitoes, ticks, and fleas

  14. HIV and AIDS • HIV(human immunodeficiency virus) causes AIDS (acquired immune deficiency syndrome) • Destroys the immune system www.vircolab.com

  15. Vaccine • A solution that contains a harmless version of a virus, bacterium, or toxin that causes an immune response.

More Related