Virus Video http://www.youtube.com/watch?v=Rpj0emEGShQ

Viruses & Bacteria can cause infection Pathogen - Any disease-causing agent 1 nanometer (nm) = one billionth of a meter 100 nm eukaryotics cells 10,000-100,000 nm viroids 5-150 nm viruses 50-200 nm prokaryotics cells 200-10,000 nm prion 2-10 nm

Virus 2 basic parts: non-living pathogen protein coat. Contains DNA or RNA non-living pathogen

Viruses have a simple structure. enveloped (influenza) polyhedral (foot-and-mouth disease) helical (rabies) capsid nucleic acid lipid envelope surface proteins capsid surface proteins nucleic acid capsid nucleic acid lipid envelope Surface proteins

All viruses have two main parts: DNA or RNA – genetic info Capsid – a protein coat

Bacteriophages: viruses that infect bacteria. capsid DNA tail sheath tail fiber

Viruses enter cells in various ways. bacteriophages pierce host cells colored SEM; magnifications: large photo 25,000; inset 38,000x

Virus inserting it’s DNA into a bacterial cell.

Viral Replication Picture http://glencoe.mcgraw-hill.com/sites/9834092339/student_view0/chapter28/life_cycle_of_t2_phage.html http://www.mcgrawhill.ca/school/schoolGraphics/biology2_1.mpg

Endocytosis (pulled into cell) Viruses enter cells in various ways. Endocytosis (pulled into cell)

Viruses enter cells in various ways. fuse with membrane

Viruses contain DNA/RNA, proteins, and they reproduce… Are viruses alive??? NO. They contain no nucleus, cytoplasm, organelles or cell membrane; they cannot carry out cell functions, and they can only “reproduce” when an infected cell builds new viruses.

Grouping Viruses Grouped according to: Presence of Capsid and envelope – shape RNA or DNA, single or double stranded – structure Viral Group Nucleic Acid Shape and Structure Example Papovaviruses DNA Icosahedral, non-env. Warts, cancer Adenoviruses Resp. & intestinal infections Herpesviruses Icosahedral, enveloped Herpes simplex, chicken pox, mono, shingles Poxviruses Complex brick, enveloped Small pox, cow pox Picornaviruses RNA Polio, hepatitis, cancer Myxoviruses Helical, enveloped Influenza A, B, C Rhabdoviruses Rabies Retroviruses AIDS, cancer

Treatment and Prevention Anti-viral drugs: interfere with viral DNA/RNA synthesis Vaccines – creates antibodies Inactivated- the virus is “dead”; cannot replicate Attenuated- the virus has been genetically altered; still functional, but won’t cause disease Attenuated tend to be more effective vaccines

Some Pictures are Graphic

The Lysogenic Cycle When viruses remain inactive within host cells for days, months or years. •Viral DNA inserted directly into the host DNA. •Viral DNA copied with host DNA during replication •Viral DNA passed on to daughter cells during mitosis •Remains dormant (no viral proteins are produced) until some “triggering event” Stress UV light heat Examples: Chickenpox and Shingles; HIV chemicals ???

POXVIRUSES Small Pox BACK

PICORNAVIRUSES - Polio BACK

Destroys the motor neurons that are producing the virus Destroys the motor neurons that are producing the virus. The result is a loss of muscle control including the diaphragm. The iron lung changes the pressure to pump air in and out of the lungs.

U.S. President Franklin Delano Roosevelt

MYXOVIRUSES Flu Virus BACK

RHABDOVIRUSES Rabies BACK

RETROVIRUSES AIDS

Herpes

HPV Tree man

Ebola

Syphilis

T4 Bacteriophages Sketch & Label the following: capsid DNA tail sheath tail fiber