Intimate Strangers The Infectious Agents of Disease

Infectious Agents VirusesViruses BacteriaBacteria ProtozoaProtozoa

Bacteria (19-1) Kingdom Eubacteria/Kingdom Archeabacteria Microscopic unicellular organismsMicroscopic unicellular organisms Free living/ ProkaryoticFree living/ Prokaryotic Self replicatingSelf replicating Usually sensitive to antibioticsUsually sensitive to antibiotics Responsible for the majority of human infectious diseasesResponsible for the majority of human infectious diseases

Review of Kingdoms Archaebacteria earliest moneransearliest monerans found in extreme habitatsfound in extreme habitats oxygen free, salty, and acidic environmentsoxygen free, salty, and acidic environments Chemosynthetic metabolismsChemosynthetic metabolisms Diff. Membrane structures (p.472)Diff. Membrane structures (p.472)Eubacteria modern bacteriamodern bacteria found in diverse number of habitatsfound in diverse number of habitats Heterotrophic (chemo and photo-) & Autotrophic (chemo and photo-)Heterotrophic (chemo and photo-) & Autotrophic (chemo and photo-) Cyanobacteria groupCyanobacteria group

Structure of Bacteria Classification by shape (morphology) Sphere Rod Spiral

Prefixes are added to the three basic shapes to further classify the bacteria according to their arrangement. The three basic arrangements are: A) Diplo-paired arrangement B) Staphylo- clustered arrangement C) Strepto- chained arrangement A B C

More Ways to Identify MovementMovement FlagellaFlagella Slime MovementSlime Movement CiliaCilia NoneNone Cell WallsCell Walls Gram Positive gives a purple color after staining Gram Negative gives a pink color after staining

-Hollow, hair like structures made of protein -Allow bacteria to attach to other bacteria -A specialized pilus, the sex pilus, allows the transfer of DNA from one bacterial cell to another Pilus -Long appendages which rotate for movement -May have one, a few, or many flagella in different positions on the cell. Flagella

Other specialized structural adaptations: Capsule Gel like coating that protects bacteria from white blood cells and chemical agents. Endospore Hard coating that is resistant to drying out, boiling, and many chemical agents *Clostridium botulinium and Clostridium tetani forms endospores and toxic poisons

Structure of a Bacterial Cell

Metabolic Diversity HeterotrophsHeterotrophs 1.Chemoheterotroph: taking in of organic molecules 2.Photoheterotroph: use photosynthesis AND take in chemicals AutotrophsAutotrophs 1.Photoautotroph: require light to perform photosynthesis 2.Chemoautotroph: no light needed, undergo chemosynthesis Please note: bacteria DO NOT have mitochondria or chloroplasts How might they carry out metabolism (Cell Resp and Photosynthesis)??

Releasing Energy Aerobic require oxygen for cellular respiration “obligate aerobes”- without oxygen they will die Anaerobic do not require oxygen for cellular respiration “obligate anaerobes”-will die in the presence of oxygen “Faculties Aerobes/Anaerobes” Can live with or without oxygen Capable of switching metabolism Fermentation vs. Cellular respiration

Reproduction Binary fission -Asexual form of reproduction -Produces identical clones -Rapid (20 min) Conjugation -Sexual form of reproduction -Pilus is used to exchange genetic material -Produces a variant, making them hard to treat with antibiotics rames.htm rames.htm

Economic Importance of Bacteria 1.Nitrogen fixation- bacteria convert atmospheric nitrogen (N 2 ) to ammonia (NH 3 ) a fertilizer for plants 2.Recycle organic material and oxygen 3.Food and beverages Food Food 4.Medicines (antibiotics) 5.Industrial uses Industrial Industrial

Antibiotics Antibiotics work by blocking vital processes in bacteria, killing the bacteria, or stopping them from multiplying.Antibiotics work by blocking vital processes in bacteria, killing the bacteria, or stopping them from multiplying. This helps the body's natural immune system to fight the bacterial infection.This helps the body's natural immune system to fight the bacterial infection. Antibiotics differ in the types of bacteria they work against.Antibiotics differ in the types of bacteria they work against. Ex: PenecillinEx: Penecillin