Viruses -nonliving pathogens -pathogen is anything that causes a disease. -Why are viruses classified as being nonliving? 1. not made up of cells 2. has no organelles 3. has no metabolism

Viruses must use living cells as host: -uses the host cell to make more viruses -can not function outside the host cell Viruses do have: -their own copy of DNA or RNA but LACKS its own cytoplasm or ribosomes so it can not do anything with the DNA.

Domain? -none/ it is not living Kingdom? -once again none/ it is not living.

General structure of a virus: 1. A core of either DNA or RNA 2. Protein Coat/capsule surrounding the genetic material. Capsules have specific shaped “receptor sites” proteins which only allow them to attach on to a specific type of cell that has a complementary shaped protein receptor.

A B C D a. Tobacco plants b. Digestive system (#1 cause of diarrhea) c. Respiratory system d. Bacteria

Rabies…..nerve cells Measles….skin cells HIV……white blood cells

#1 enemy of a bacteria cell Copyright Pearson Prentice Hall

Viruses cause: -Common colds -Chicken pox -Measles -AIDS -Warts -Cold sores -Flu

Two types of Viral Infections: 1. Virulent Viruses: -causes illnesses immediately -Ex/ flu and common cold -enter the “Lytic Cycle”

Lytic Cycle:

2. Temperate Virus -does not cause disease immediately but exist inside host for weeks, months or even years. -EX/ AIDS, Warts, Cold sores

Lysogenic Cycle:

Control of viruses within our bodies: Our own defense system Our bodies 1st line of defense: - Skin -pathogen must enter through an opening.

Our bodies 2nd line of defense: -White blood cells (WBC’s) -WBC’s leave blood stream and travel to the site of infection. -WBC’s engulf the pathogen. Recipe for pus?????

Our bodies 3rd line of defense: -Antibodies -Proteins made by WBC’s -Very specific/memory cells -For each foreign body that enters your body, your WBC’s makes a specific antibody to destroy it. -Remain in your body and can be used at anytime.

Example: Get the measles or chicken pox once, you build up antibodies which will protect you for life from getting them again. Chicken pox Measles

Vaccine: -injection of a weakened form of a virus -stimulates body to make antibodies -stays in body and destroys virus if it enters

Booster shot: -revaccination to “boost” your immunity.