Comparing Viruses and Bacteria

Pathogens Pathogens are anything capable of causing infectious disease.

Have you ever experienced a cold or the flu? If so, then you have had a close encounter with a virus.

Are viruses alive? What do you know about viruses? Did you see them in any of the taxonomic groupings?

Viruses Virus: Non-living strand of genetic material within a protein coat; requires a host Parasitic Viruses are not considered to be living because they are not made of cells and do not exhibit most of the characteristics of life. Host: - any organism that is used by a parasite to complete its lifecycle

Host specific:- most virus or bacteria will only affect a single host or a small group of host species Viruses attach to specific sites on cells called “docking sites” West Nile Virus – affects birds, horses, and people Influenza type B – affects only people not others Parvo – affects only dogs, not other organisms

Virus Structure: Capsid- an outer protein coat for protection Glycoproteins - Used to attach to the host. DNA or RNA core (genetic material) - holds the genetic material that will affect the host There may be other components, such as a tail or fibers, in some viruses

How do viruses affect you? They blow up the cells that they affect!! There are two different ways First - Lytic Cycle: Lysis – to break or rupture cells or cell membranes steps 1. Attach - Virus “docks” with host cell 2. Entry - virus inject it’s DNA/RNA into host cell 3. Replicate and Assemble - replication of virus parts 4. Lysis - cell ruptures and new virus’ invade tissues of the host

Second – Lysogenic Cycle 1. Attach steps 2. Entry 3. Provirus Formation - DNA attaches to the cells own DNA 4. Cell Division 5. Stress 6. Replicate and Assemble 7. Lysis

Examples of Lytic Virus infections: Influenza Caused by several types of influenza viruses HIV/AIDSCaused by the human immunodeficiency virus; This type of virus is called a retrovirus because it contains RNA instead of DNA.

Examples of Lysogenic Virus infections Chicken Pox - caused by Herpes Virus Shingles - caused by Herpes Virus Coldsores/ Feverblisters - caused by Herpes Virus

Bacteriophage: a virus that infects bacteria Bacteriophages can cause scarlet fever and toxic shock syndrome.

How does your body fight Viral Infections? After enough cell debris ( from blown up cells ) is detected your Immune system gets involved. White blood cells to the rescue !! Macrophage -large white blood cells that get rid of debris by eating it. When they eat too much, they die. These dead cells and the cell debris are “puss”

Other white blood cells pick up viral particles from the battle and carry it to Lymph nodes. In the lymph nodes, they look for cells to fight this type of virus. T- cells (thyroid cells) are called upon and go to the site of the infection to kill specific infected cells B-cells (bursal cells) make antibodies that go to the site and kill free viruses The virus is “killed” 21 days from first infection

How does your body fight Viral Infections? Immunizations – using vaccines to help the body gain immunity by introducing small doses of the infection Vaccine: An injection of a killed or weakened pathogen Antibiotics are not used against viruses!

Bacteria!!!! -unicellular, prokaryotic organisms that sometimes cause disease 1. Shape Bacteria come in three shapes. Cocci - spherical shaped Bacilli – rod shaped Spirilla – corkscrew shaped

Growth of Bacteria: Binary Fission: Similar to Mitosis - splitting Conjugation: Similar to sexual reproduction. Passing of genetic material Spore Formation: Creating hard coatings to protect during unfavorable conditions. spore conjugative connection

Diseases of Bacteria: 1. Coccus diseases Streptococcus pharyngitis Strep throat Neisseria meningitidis Bacterial meningitis 2. Bacillus diseases Bacillus anthracis Anthrax Yersinia Pestis Bubonic Plague 3. Spirillum diseases Treponema pallidum Syphillis Borellia burgdorferia Lyme disease

Bacteria hurt you by…………. Poisoning your cells!!! Once inside the host, they begin to release metabolic waste called toxins. Your Immune system usually cannot fight bacterial infections alone. Antibiotics kill Bacteria!

Review for test Define terms VirusHostHost Specific CapsidSurface Membrane Proteins DNA/RNA coreLysisLytic Cycle Lysogenic CycleMacrophageT-cells B –cellsCocciBacilli SpirilliAntibioticBinary fission ConjugationSpore Formation Questions 1. Draw and label both the Lytic and Lysogenic cycles. 2. Draw and give examples of all three types of bacteria.