Viruses

Viruses: -NONLIVING (not made of cells) -Smaller than Prokaryotes (bacteria) -Able to reproduce rapidly (only in host cell)

-Capsid-Protein Coat (helps virus enter cells) Viruses consist of: -Capsid-Protein Coat (helps virus enter cells) -RNA or DNA

What do Viruses look like? RCSB PDB, 2008 What do Viruses look like? Tailed phages Viruses are commonly either icosahedral or helical. Some viruses are enveloped with a membrane. Tailed phages have a complex structure with a phage head, where the genetic material is packaged, a helical tube and tail fibers to attach to the host cell surface.

Viruses may attack: -Eukaryotes (plant or animal) -Prokaryotes called Bacteriophages Uses the host’s organelles to replicate (copy)

Illnesses caused by viruses RCSB PDB, 2008 Illnesses caused by viruses Common cold Flu AIDS Bird flu Polio Electron micrographs of viruses. HIV Aeromonas virus 31 Influenza virus Orf virus Herpes simplex virus Smallopx virus Viruses are made of genetic material (DNA or RNA) packaged in a protein shell. They are small (10 nm-3 microns in diameter) and have icosahedral, helical or other complex shapes. Colored electron micrographs of some disease causing viruses are seen in this slide.

NO!!! They are specific. Viruses: Bind to specific host cell before it can enter it (lock and key) Can plant viruses infect animals? NO!!! They are specific.

How Viruses Replicate- 1) Lytic Cycle- destroys host cell quickly OR 2) Lysogenic Cycle- its DNA becomes part of host cell and tells it to replicate (like a Zombie Cell)

Lytic Cycle

Lysogenic Cycle

Common Viruses Influenza (flu) Spread by: 1) Direct Transmission (sneeze/cough directly into eyes, nose mouth)

Common Viruses Human Immunodeficiency Virus (HIV)

HIV Specific to “Helper” T Cell (T-Cells help the immune system respond to different pathogens like bacteria/viruses) Kills “Helper” T Cells -eventually destroying Immune System

HIV Transmitted 4 ways: -Sexually -Contaminated Needles -Infected blood -Breast milk -At birth (mother to baby)

HIV After years of battling HIV, body becomes unable to fight off infections and person will have developed Acquired Immune Deficiency Syndrome (AIDS)

HIV & AIDS Not virus or disease that eventually kills the person– inability to fight off anything, including the common cold