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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 Prokaryotes • 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 • __________________________-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: Bacillus or bacilli – by shape • 1) rod-shaped are __________________ • 2) spiral-shaped are_______________________ • 3) spherical-shaped are cocci(coccussingular) 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 • • Chemoheterotrophs Heterotrophs – _____________________-must take in organic molecules for energy and supply of Carbon-as do we – _____________photoheterotrophs Autotrophs – ____________________– ______________-as those found in volcanic vents 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 capsid • 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 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 Lysogenic Lytic • _______________________________contain RNA as genetic info and produce DNA copy of RNA retroviruses III. Diseases vaccination • 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 antibiotic • 2)controlsterilization,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 viroids – ________________________________singlestranded RNA moleculesw/no capsid-attack plants – ______________________-virus –like particles of protein-may cause protein clumps that induce new prions---example-Mad Cow Disease prions
