What is a Microbe?What is a Microbe?
Microscopic organisms that exist as single cells or cell clusters. Too small to be seen w/out a
microscope.
Classified into 2 CategoriesClassified into 2 Categories
Prokaryotes: organisms that do NOT have a membrane-enclosed nucleus. Ex) Bacteria
Eukaryotes: contain membrane-enclosed organelles such as a nucleus. Ex) Animal Cells and Protists
VirusesViruses
Tiny NON-LIVING particle that enters and then reproduces inside a living cell.
Considered to be NON-LIVING because they are not cells and cannot make or take in food.
Size of VirusesSize of Viruses
Structure of a VirusStructure of a Virus
All viruses have 2 basic parts: a protein coat that protects the virus and an inner core made of genetic material.
Come in different shapes.
FilovirusFilovirus
Do not have a distinct, uniform shape
Ex)Ebola
Polyhedral VirusPolyhedral Virus
Geometric appearance, look like crystals
Ex) Polio
Envelope With ProjectionsEnvelope With Projections
Spherical shape with projections
Ex) Flu, HIV
BacteriophageBacteriophage
Resembles a spacecraft. Attacks only bacteria
Ex) E.coli
How Viruses MultiplyHow Viruses Multiply
Although viruses can multiply, they do so differently than organisms. Viruses can multiply ONLY when they are inside a living cell.
Host: organism that provides a source of energy for a virus or another organism.
Parasite: an organism that lives on or inside a host and causes it harm.
How Viruses MultiplyHow Viruses Multiply
Once inside a cell, a virus’s genetic material takes over many of the cell’s functions.
It instructs the cell to produce the virus’s proteins and genetic material.
The proteins and genetic material then assemble into new viruses.
Active v. HiddenActive v. Hidden
Active viruses enter cells and immediately begin to multiply leading to the quick death of the invaded cells.
Hidden viruses “hide” for a while inside host cells before becoming active.
Active VirusActive Virus
Hidden VirusHidden Virus