Engage • Ebola: The Plague Fighters • Pathogens – How are they transmitted
Explore • TMV – Tobacco Mosaic Virus • Models of Viruses
What is a Virus? • Virus Latin for Poison • Non-cellular particle with • DNA or RNA • 1 or 2 Protein Coats (Capsids) • May have Viral Envelope - Phospholipids • DO NOT respire or grow • ONLY function in a living cell • NOT given Latin names like living organisms (rabies virus) (polio virus) (adenovirus=adenoid tissue)
Questions/Discussion • Do Viruses Respire? • What type of genetic material do viruses have? • Can they have both DNA and RNA?
How are they Classified? • Shape of their protein coat (capsid) • Important in infection • Type of nucleic acid they contain • DNA or RNA • NEVER Both
How do Viruses Replicate? • The lytic cycle: 1- absorption/attachment 2- injection/entry 3- replication of viral parts 4- assembly 5- release by lysis • Results in death of host cell • Virulent virus (only lytic cycle)
Lysogenic Cycle • First steps just like lytic!! • Does NOT destroy the host cell • Nucleic acid joins the cell’s DNA. Viral DNA becomes a part of hosts cell DNA (prophage) • Could go on for years • Temperate virus (capable of using the lytic and lysogenic cycles) • i.e. HIV, cold sores, shingles
Types of Viruses • Animal viruses: Rabies, Polio, Mumps, Chicken pox, Small pox, and Influenza. • Plant Viruses: Tobacco mosaic virus (TMV), Banana streak virus, Carrot thin leaf virus • Bacterial Virus: Bacteriophages ( T1, T2, T3, and T4.) • SPECIFIC in what type of cell and what type of organism they infect • Polio – human nerve cell • T4 – only certain strains of E. coli
Different Types of Viruses • ADENOVIRUS • Respiratory infections; colds
Influenza Virus • Virus that causes the flu
Retroviruses • RNA viruses that contain reverse transcriptase • This enzyme allows RNA to produce DNA • HIV is an example of the virus
Questions/Discussion • What some differences between the lytic and lysogenic cycle? • What type of virus is HIV? • How is HIV one of the most successful viruses in reproducing?
Elaborate • Lytic and Lysogenic Manipulative