VIRUSES B 4.C Compare the structures of viruses to cells, describe viral reproduction, and describe the role of diseases such as human immunodeficiency virus (HIV) and influenza

Videos – Viral invasion of the body Part 1 http://www.youtube.com/watch?v=D2Uuc76DvlI&feature=youtu.be http://www.youtube.com/watch?v=soIDiqxtTjM&feature=youtu.be Part 2

What is a Virus? Much smaller than cells A NON-LIVING infectious agent made up of a core of DNA or RNA surrounded by a protein coat. Viruses need host cells to replicate the viral DNA. They enter a living host cell and hijack it to produce more viruses Viruses eventually kill their host cells (Reproduce)

Parts of a Virus Capsid: Protein coat Genetic core: DNA or RNA IS NOT LIVING!!!!!!! IS NOT A CELL!!!!!!! DOES NOT have organelles!!!!

Protein Coat (part that hold the DNA) Legs (anchor the virus to the cell)

Viruses cannot be destroyed by antibiotics!!!! A cure for viruses? No said “cure” for a virus, only preventions Vaccine —weakened or deadened form of a virus Viruses cannot be destroyed by antibiotics!!!! Antibiotics are for bacteria – not viruses!

We Classify Viruses by: Shape (what they look like) Host (the type of cell they infect) Function (how they infect cells) Genetic Core (DNA or RNA)

Viral Shapes Shape: Binal Helical Enveloped Examples: Tobacco Mosaic RNA Capsid proteins Head Tail sheath DNA Tail fiber RNA Capsid Surface proteins Membrane envelope Examples: Tobacco Mosaic Virus Influenza Virus T4 Bacteriophage

CAPSID WEST NILE VIRUS HERPES SARS

HEPATITIS B BIRD FLU

One Type of Viral Replication Virus attaches to host cell Virus injects DNA or RNA into cell Viral DNA or RNA is replicated or reverse-transcribed Transcription and Translation takes place to make capsid Cell assembles viruses Cell is lysed, new viruses are released and infect other cells

Cell Virus

Viruses that affect humans Influenza (the flu) HIV Chicken pox; Shingles Herpes Common colds Epstein Barr HPV Rabies Measles Mumps Rubella Polio West Nile Hepatitis A, B, C Ebola Small pox

Human Immunodeficiency Virus HIV causes AIDS HIV attacks Helper T-Cells, which are vital to our immune system Since HIV decreases the immune system, a person is more prone to secondary infections than a normal person Mutates too quickly to make a vaccine

InFLUenza Symptoms: High fever, sore throat, fatigue, aches, coughs Mutates regularly. That is why we have vaccines yearly Can be air borne - When some one coughs or sneezes, you can contract the virus by breathing it in. What shape are these viruses?

SARS Severe acute respiratory syndrome Airborne- can be transmitted when an infected person coughs or sneezes.

Common Colds Upper respiratory infections (nose, throat, lungs) Usually clear up in 2 weeks without complications More than 200 known viruses can cause colds

Small pox Virtually eradicated! Small pox vaccine was made from cowpox Only found in 2 labs on Earth: Russia and US Small pox vaccine was made from cowpox Symptoms: High fever, aches, rashes

Human Papilloma Virus (HPV) Affects both men and women Sexually transmitted Can cause cervical cancer Gardasil – vaccine that may prevent cervical cancer

Herpesvirus Chicken Pox Fever Incubation of 14 days Red itchy rash Vaccination available Other herpesviruses include Herpes (cold sores and genital herpes)

Measles High fever Sore throat, cough, sneezing Rash Dangerous for pregnant women You received a vaccine for MMR (measles, mumps, rubella)

Polio Symptoms: Fever, headache, muscle weakness, difficulty swallowing Hundreds of thousands affected until vaccination became available Franklin D. Roosevelt, President from 1932 to 1945

Ebola 1977 Ebola Zaire (picture) Named after the Ebola River in Zaire High hemorrhagic fever High death rate

Viruses vs. Cells