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