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MICROBIOLOGYIntroduction
Viruses
INTRODUCTION Microbiology studies the microscopic world
Leeuwenhoek - Father of microscopy- Made significant Improvements to the microscopePasteur – father of microbiologyhttp://www.biography.com/people/louis-pas
teur-9434402
INTRODUCTION
Included in this unit:Viruses – noncellular particlesMonera (Archaebacteria and
Eubacteria) – single-celled with no membrane bound organelles, prokaryotic
Protista – single-celled with membrane bound nucleus and organelles, eukaryotic
OUR GOAL IN THIS SECTION
Evaluate the evidence used to classify viruses as living or non-living
VIRUSESLiving or Nonliving
Structure
ARE VIRUSES LIVING?
Living things must meet the following criteria: Cellular Have a metabolism Have a life span Reproduce Respond to their Environment
We will revisit this question after learning more about viruses.
VIRUSES: AN INTRODUCTION
Edward Jenner and The Small Pox Storyhttp://www.youtube.com/watch?
v=jJwGNPRmyTI Human diseases:
HIV West Nile SARS Ebola
Studying these viruses could be very dangerous to one’s health... Most studied virus is the bacteriophage Infects Escherichia coli (E. coli)
STRUCTURE
Non-cellular Various sizes and shapes Basically a nucleic acid surrounded by a
protein coat (capsid) Can contain DNA or RNA
PROTEIN COAT- THE CAPSID
Proteins on the surface of both cells and viruses Some provide structure and shape Can be enzymes Can move things in and out of a cell Use ATP to create movement
VIRAL SPECIFICITY
Related to the protein coat To infect a cell the virus must match the
proteins on the surface the cell it infects That is why there are viruses that infect
humans and not other animals (and vice versa)
Antigens markers (molecular markers)
ENCAPSULATED VIRUSES
Gain a membranous envelope from their host cell during infection cycle
Acts like a camouflage that hides the virus from the host immune system
The envelope contains matching proteins to the host cell
ASSIGNMENT
Revisit the living criteria… are viruses living or nonliving?
Create a T-chart of living vs nonliving characteristics of viruses