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

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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