VIRUSES

Viruses are not living organisms Viruses do not Grow Have homeostasis Metabolize Viruses do Infect cells and use the cell to make more viruses Cause disease in many organisms

Tobacco mosaic virus (TMV) Virology – study of viruses First discovered in Tobacco plants in 1935 Since then many viruses have been identified.

The Structure Of a Virus Viruses are composed of a core of nucleic acid The Nucleic acid core is surrounded by a protein coat called a capsid The Nucleic core is either made up of DNA or RNA but never both

RNA or DNA? Viruses with RNA Viruses with DNA Human immunodeficiency virus (HIV)/AIDS Influenza viruses Rabies Hepatitis Some Cancers Viruses with DNA Warts Chickenpox Mononucleosis Herpes Smallpox Some cancers RNA -Bird Flu Virus

Virus Shapes Helical Rodlike with capsid proteins winding around the core in a spiral Tobacco Mosaic Virus

Virus Shapes Polyhedral Has many sides Most polyhedral capsids have 20 sides and 12 corners

Virus Shapes Polyhedral capsid attached to a helical tail.

Viruses Enter Living Cells Viruses enter bacterial cells by punching a hole in the cells wall and injecting its DNA

E. Coli and the Bacteriophage What it looks like in real life

LYTIC Cycle In the lytic cycle, the virus reproduces itself using the host cell's chemical machinery. The red spiral lines in the drawing indicate the virus's genetic material. The orange portion is the outer shell that protects it.

Lysogenic Cycle In the lysogenic cycle, the virus reproduces by first injecting its genetic material, indicated by the red line, into the host cell's genetic instructions. Viruses in this cycle can lay dormant for many years. HIV….AIDS

Mutating viruses Viruses can mutate when they copy the genetic material Copy something wrong Mistake proves useful More powerful virus (more infectious) Viruses don’t mutate often, except… Influenza HIV Flu

The spread of West Nile virus (1999 – 2002) – bird, horse, mosquito or human

AIDS Worldwide

There are approx. 14,000 new cases of HIV worldwide every day Think about it… In the US, there is better than a 1/1000 chance of contracting HIV during unprotected sex A person can be contagious for more than 10 years before any sign of the disease is apparent HIV becomes AIDS when the number of immune cells drops below a predetermined number No one dies from HIV or AIDS; people die from secondary infections (ranging from the common cold to cancer) More than 3 million people (size of Chicago) die each year There are approx. 14,000 new cases of HIV worldwide every day

How Is HIV Spread? Sexual contact Sharing contaminated needles Blood transfusions Breast feeding (mother to baby) Mother to baby during pregnancy or birth

Vaccines Vaccine - A weakened version of the virus that a body can beat. Chicken Pox Small Pox Measles Mumps Biological Warfare????

Viruses and Cancer Cancer- uncontrolled reproduction of cells. Can be triggered by lysogenic viruses HPV- Human Papillomavirus – cervical cancer Now we have a vaccine… Could ALL cancers be cause by viruses???