Chapter 14 principles of disease & epidemiology. The Germ Theory of Disease.
Chapter 20 Bacteria & Viruses. Germ Theory Discovery that microorganisms are PATHOGENS (disease...
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Transcript of Chapter 20 Bacteria & Viruses. Germ Theory Discovery that microorganisms are PATHOGENS (disease...
Chapter 20
Bacteria & Viruses
Germ Theory
• Discovery that microorganisms are PATHOGENS (disease causing agents) The germ theory of disease states that some diseases are caused by microorganisms. These small organisms, too small to see without magnification, invade humans, animals, and other living hosts. Their growth and reproduction within their hosts can cause a disease.
I. Bacteria
• Are ________________________-lack a nucleus and have few organelles
• Much smaller than eukaryotes• Eubacteria-larger kingdom than
archaebacteria;usually have protective cell wall and determines shape
Prokaryotes
• __________________________-not such a strong,if any,cell wall,DNA sequences more like eukaryotes;live in HARSH environments like hot springs or volcanic vents
Archaebacteria
Identifying bacteria:
– by shape• 1) rod-shaped are __________________• 2) spiral-shaped
are_______________________• 3) spherical-shaped are cocci(coccus-
singular)
Bacillus or bacilli
Spirillus or spirilla
• by cell walls-use Gram Staining-Gram(+) have thick_______________________walls/gram(-) have thinner walls
• by movement-some do not move and some have flagella
peptidoglycan
B. Metabolic Diversity
• Heterotrophs– _____________________-must take in organic molecules
for energy and supply of Carbon-as do we– _____________-
• Autotrophs– ____________________-– ______________-as those found in volcanic vents
Chemoheterotrophs
photoheterotrophs
photoautotrophs chemoautotrophs
Releasing Energy
– 1) Obligate aerobes-need constant supply of O2– 2) _______________________-do not need O2– 3) Faculatative anerobes-can survive w/or w/o
O2-example-E.coli
Obligate anaerobes
C. Growth and Reproduction
• _________________________grows,replicates DNA
and splits in half
Binary fission
• ________________________-exchange genetic info w/ a “bridge”
conjugation
• Some produce_________________________, which can lie dormant and germinate
spores
D. Importance of Bacteria
• Decomposers
• N-fixers-for plants
• Human uses-food production ;cleaning up oil spills
• Assist digestion
II. Viruses-particles of nucleic acids,protein and sometimes lipids
• Not living-reproduce only by infecting living cells• Usually has a DNA or RNA core w/outer protein coat• Outer protein coat called a ______________-which
enable it to enter a host cell—often destroying host cell
• ________________________-viruses that infect bacteria
capsid
bacteriophage
• ____________________infection-virus enters cell,makes copies ,and causes cell to burst
• _____________________________-virus integrates DNA into DNA of host cell,and viral genetic info replicates along w/host
Lytic
Lysogenic
• _______________________________-contain RNA as genetic info and produce DNA copy of RNA
retroviruses
III. Diseases
• Bacterial– Infect by damaging cells or releasing toxins– Mycobacterium tuberculosis– Streptococcus– Cornyebacterium diptherae– Anthrax– Lyme’s disease– Tetanus– Meningitis– Tooth decay
• prevention – -_______________________preparation of weakened
or killed pathogens– ________________________-compounds that block
the reproduction or growth of bacteria
vaccination
antibiotic
• 2)control-sterilization,heat,disinfectantants,proper food processing and storage
B. Viral
• Common cold• Influenza• Smallpox• Warts• AIDS• Chickenpox• Measles• Hepatitis A,B, or C• West Nile• Polio
– ________________________________single-stranded RNA moleculesw/no capsid-attack plants
– ______________________-virus –like particles of protein-may cause protein clumps that induce new prions---example-Mad Cow Disease
viroids
prions