virus power point
DESCRIPTION
TRANSCRIPT
![Page 1: Virus Power Point](https://reader035.vdocuments.mx/reader035/viewer/2022062617/54bdd1664a795904268b4569/html5/thumbnails/1.jpg)
VirusesChp 21
QuickTime™ and a decompressor
are needed to see this picture.
http://www.airmanager.com/new/images/virus460.jpg
![Page 2: Virus Power Point](https://reader035.vdocuments.mx/reader035/viewer/2022062617/54bdd1664a795904268b4569/html5/thumbnails/2.jpg)
Viruses
Viruses possess only a portion of the properties of “living” organisms– Segments of DNA or RNA wrapped in a
protein coat called a capsid• No Metabolism • Must reproduce within cells
![Page 3: Virus Power Point](https://reader035.vdocuments.mx/reader035/viewer/2022062617/54bdd1664a795904268b4569/html5/thumbnails/3.jpg)
Key Concepts
Non-cellular infectious agents Composed of nucleic acid, DNA or RNA and protein
Characteristic of Life
Virus Cell
Growth No Yes
Homeostasis No Yes
Metabolism No Yes
Mutation Yes Yes
Nucleic Acid DNA or RNA DNA
Reproduction Only within host cell Independently by cell division
Structure Nucleic acid core, protein covering, some have envelope
Cytoplasm, cell membrane, etc.
![Page 4: Virus Power Point](https://reader035.vdocuments.mx/reader035/viewer/2022062617/54bdd1664a795904268b4569/html5/thumbnails/4.jpg)
All viruses have 2 main parts:
1. DNA or RNA - genetic info
2. Capsid - a protein encasement
![Page 5: Virus Power Point](https://reader035.vdocuments.mx/reader035/viewer/2022062617/54bdd1664a795904268b4569/html5/thumbnails/5.jpg)
Viral Shapes
General Structure:– Helical- rod-shaped protein coat wound
helically around nucleic acid core– Polyhedral- many-sided coat– Enveloped- envelope around virus is made
mostly of membrane remnants from previously infected cell
![Page 6: Virus Power Point](https://reader035.vdocuments.mx/reader035/viewer/2022062617/54bdd1664a795904268b4569/html5/thumbnails/6.jpg)
Helical Virus
http://www.mcb.uct.ac.za/tutorial/virovirion.jpg, http://textbookofbacteriology.net/themicrobialworld/hsv1struc.jpg, http://www.iayork.com/Images/2008/3-10-08/AdenovirusModel.jpg
Enveloped VirusAdenovirus (Polyhedral)
![Page 7: Virus Power Point](https://reader035.vdocuments.mx/reader035/viewer/2022062617/54bdd1664a795904268b4569/html5/thumbnails/7.jpg)
http://2.bp.blogspot.com/_aPfF45kK_Bg/RyT7ZGjngFI/AAAAAAAAAM8/eR6I9tdzafM/s320/BacteriophageCartoon.jpg
http://www.brooklyn.cuny.edu/bc/ahp/LAD/C4b/graphics/C4b_TMV.GIF
http://www.apositivelife.com/images/graphs/bio.jpg
![Page 8: Virus Power Point](https://reader035.vdocuments.mx/reader035/viewer/2022062617/54bdd1664a795904268b4569/html5/thumbnails/8.jpg)
The influenza virus has an envelope derived from the host cell. It consists of proteins, lipids and glycoproteins. The envelope helps the virus evade the host cell’s immune system.
![Page 9: Virus Power Point](https://reader035.vdocuments.mx/reader035/viewer/2022062617/54bdd1664a795904268b4569/html5/thumbnails/9.jpg)
Virus leaving host cell enveloped by host cell membrane
![Page 10: Virus Power Point](https://reader035.vdocuments.mx/reader035/viewer/2022062617/54bdd1664a795904268b4569/html5/thumbnails/10.jpg)
Grouping Viruses Grouped according to:
– Presence of capsid and envelope - shape
– RNA or DNA, single or double stranded - structure
Viral Group Nucleic Acid
Shape and Structure Example
Papovaviruses DNA Icosohedral, non-env Warts, cancer
Adenoviruses DNA Icosohedral, non-env Resp. & intestinal infections
Herpesviruses DNA Icosohedral, enveloped Herpes simplex, chicken ox, mono, shingles
Poxviruses DNA Complex brick, enveloped Small pox, cow pox
Picornaviruses RNA Icosohedral, non-env Polio, hepatitis, cancer
Myxoviruses RNA Helical, enveloped Influenza A B C
Rhabdoviruses RNA Helical, enveloped Rabies
Retroviruses RNA Icosahedral, enveloped HIV
![Page 11: Virus Power Point](https://reader035.vdocuments.mx/reader035/viewer/2022062617/54bdd1664a795904268b4569/html5/thumbnails/11.jpg)
Viral Multiplication Cycles
5 Steps– Attachment– Penetration– Replication– Assembly– Release
•Lytic pathway•Host cell lysis relatively immediate
•Lysogenic pathway•Viral DNA integrates into bacterial chromosomes, there is a period of dormancy.
![Page 12: Virus Power Point](https://reader035.vdocuments.mx/reader035/viewer/2022062617/54bdd1664a795904268b4569/html5/thumbnails/12.jpg)
http://www.sciencegateway.org/resources/biologytext/cb/virus/phagerep.gif
![Page 13: Virus Power Point](https://reader035.vdocuments.mx/reader035/viewer/2022062617/54bdd1664a795904268b4569/html5/thumbnails/13.jpg)
http://www.accessexcellence.org/RC/VL/GG/images/examples_of_viral.gif
![Page 14: Virus Power Point](https://reader035.vdocuments.mx/reader035/viewer/2022062617/54bdd1664a795904268b4569/html5/thumbnails/14.jpg)
Disease Causing Viruses
Emerging Viruses– Viruses that evolve in a geographically
isolated area and are pathogenic (disease causing) to humans
Viruses and Cancer– Viruses are capable of altering growth
properties of humans cells they infect by triggering oncogene expression (HPV)
![Page 15: Virus Power Point](https://reader035.vdocuments.mx/reader035/viewer/2022062617/54bdd1664a795904268b4569/html5/thumbnails/15.jpg)
Prions and Viroids
Prions– Infectious protein conformations containing no
genetic material. They can cause normal proteins to assume an abnormal shape preventing proper function (Mad Cow Disease)
Viroids– Tiny, circular molecules of RNA
• No protein or membrane coat• Important infectious disease agents in plants