disease notes - weebly
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Disease Notes Bacteria and Viruses
Disease Agents (Pathogens)
S There are many organisms in the world that can cause diseases
1. Bacteria 2. Viruses
3. Protists
4. Fungi
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Bacteria
S Prokaryote
S Unicellular (Only ONE Cell)
S Bacteria have: S Cell Wall
S DNA
S Capsule
S Endospore (protective outer covering)
S No Nucleus
S Free Floating DNA
Bacteria Shapes
S Three Shapes 1. Bacillus (Rods)
2. Spirrilum (Spirals)
3. Coccus (Spheres)
S Arrangements S Diplo- (2)
S Staphlo- (Clusters)
S Strepto- (Straight line)
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Treating Disease Agents
S Bacteria can be treated by antibiotics. They will kill the bacteria. Viruses cannot be treated at all. They have to run their course.
S Protists (like amoebic dysentery) and fungi (like athlete’s foot) can be treated by a variety of medicines.
Bacterial Resistance
S If you try to treat a sickness that is not caused by a bacteria with an antibiotic, or if you do not take your antibiotics correctly (not taking ALL of them) this may cause bacterial resistance (MRSA)
S We call these SUPERBUGS
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Viruses
S Viruses are non-living organisms/things. They are considered to be non-living because they can not reproduce on their own successfully.
S They have to have a “Host Cell” which is YOU (or whatever organism it is infecting) This one of the characteristics of life.
S They also do not contain cells.
Viral Structure
S Viruses come in many different shapes – practically any shape you can think of.
S BUT! All Viruses have certain things in common 1. Nucleic Acid (DNA or RNA)
2. Capsid (Used for protection)
3. Very, very, very small – much smaller than bacteria
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Vaccines
S Viruses can be prevented – not treated by vaccines
S Once you have a viral disease, it has to run its course
S You can prevent some viral diseases by vaccines
S In a vaccine, a weak strain of the virus is injected into the organism and the organism produces antibodies to fight off the virus next time the body is exposed to it!
Viral Reproduction
S Viruses can reproduce in two ways – depending on the type of virus 1. Lytic Cycle (Flu)
2. Lysogenic Cycle (HIV)
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Lytic Cycle
S Virus attaches to host cell
S Virus enters nucleus of host cell
S Virus replicates MANY times
S Viruses break out of host cell to infect other cells.
S VIRUS ATTACK!
Lysogenic (Latent) Cycle
S Virus attaches to host cell
S Virus enters nucleus of host cell and its DNA becomes part of the host cells DNA
S Virus can become inactive for long periods of time
S As the host cell duplicates through mitosis, the viral DNA is also replicated
S Eventually, the virus breaks out of the cells