BEAUTIFUL but DEADLY

1. A virus is an infectious agent made up of nucleic acid (DNA or RNA) wrapped in a protein coat called a capsid.

2. Viruses have no nucleus, no organelles, no cytoplasm or cell membrane—Non-cellular

vs

3. This is why it does NOT belong to any kingdom.

Replication is how a virus spreads.A virus CANNOT reproduce by itself—it must invade a host cell and take over the cell activities, eventually causing destruction of the cell and killing it. (The virus enters a cell, makes copies of itself and causes the cell to burst releasing more viruses.) DNA/RNA is

copied.DNA/RNA injected

into cell.Virus attaches to cell.

Virus copies itself.

Cell bursts (lyses) and releases new viruses.

Step 1 Step 2 Step 3

Step 4 Step 5

Certain viruses can only attack certain cell types. They are said to be specific.

It’s like the pieces of a puzzle. The ends have to match up so only

certain pieces fit.

Surface Markers

Receptor Sites

Example: The rabies virus only attacks brain or nervous cells.

Virus

Cell

Surface Markers

Receptor Sites

Virus

A virus recognizes cells it can infect by matching its surface marker with a

receptor site on a cell.

Cell

Capsid (protein coat)– inside contains either RNA or DNA

Surface Marker

DNA or RNA

Capsid (protein coat)

1. Bacteriophage—viruses that infect bacteria

2. Flu (influenza), HIV

HIV

Tobacco Mosaic

Potato X

Adenovirus

Bacteriophage

THE FIVE VIRUSES MODELED IN LAB ACTIVITY: Animals, plants and bacteria are all susceptible to viruses.

NANOCELLS: HOW BIG????

*•PIN • 1x *

BATSCarrier of the Rabies virus. It is a preventable viral disease of mammals most often transmitted through

the bite of a rabid animal. The overwhelming majority of rabies cases reported to the Centers for Disease Control and Prevention (CDC) each year occur in wild animals like raccoons, skunks, bats

and foxes.

MOSQUITOCarrier of West Nile Virus. When fall arrives and temperatures decrease, the mosquito population

consequently declines. However, migration season is shortly after, and as birds and mosquitos travel, they bring the virus with them. There are currently 110 species of infected birds, and the number of mosquito species who can transmit the virus has

jumped from one to eight.

VIRAL VECTORS

Tobacco leaves and tomatoes infected with Tobacco Mosaic Virus

NON-VECTOR VIRAL DISEASESPOTATO X VIRUS