1. The Infectious Agents of Disease
Intimate Strangers
The Infectious Agents of Disease

2. Infectious Agents
Viruses
Bacteria
Protozoa

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

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

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

6. Prefixes are added to the three basic shapes to further classify the bacteria according to their arrangement.
The three basic arrangements are:
1) Diplo-paired arrangement
2) Staphylo- clustered arrangement
3) Strepto- chained arrangement

7. More Ways to Identify Movement Cell Walls Flagella Slime Movement
Cilia
None
Cell Walls
Gram Positive gives a purple color after staining
Gram Negative gives a pink color after staining

8. Pilus
These are hollow, hair like structures made of protein allow bacteria to attach to other cells. A specialized pilus, the sex pilus, allows the transfer of DNA from one bacterial cell to another
Flagella
The purpose of flagella (sing., flagellum) is motility. Flagella are long appendages which rotate. Bacteria may have one, a few, or many flagella in different positions on the cell.

9. Other specialized structural adaptations:
Capsule
gelatinous 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

10. Structure of a Bacterial Cell

11. Metabolic Diversity Heterotrophs
Chemoheterotroph: taking in of organic molecules
Photoheterotroph: use photosynthesis AND take in chemicals
Autotrophs
Photoautotroph: require light to perform photosynthesis
Chemoautotroph: no light needed, undergo chemosynthesis

12. Releasing Energy Aerobic Anaerobic “Faculties Aerobes/Anaerobes”
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

13. 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

14. Economic Importance of Bacteria
Nitrogen fixation- bacteria convert atmospheric nitrogen (N2) to ammonia (NH3) a fertilizer for plants
Recycle organic material and oxygen
Food and beverages
Medicines (antibiotics)
Industrial uses

15. Identifying Bacteria- What is gram staining?
Gram reaction is based on the structure of the bacterial cell wall. 1. In Gram-positive bacteria, the purple crystal violet stain is trapped by the layer of peptidoglycan which forms the outer layer of the cell. 2. In Gram-negative bacteria, the outer membrane prevents the stain from reaching the peptidoglycan layer in the periplasm. The outer membrane is then permeabilized by acetone treatment, and the pink safranin counterstain is trapped by the peptidoglycan layer.

16. Check It Out

17. Results

18. Why is the cell wall and gram staining important?
Acquired resistance
Many bacteria acquire resistance to one or more of the antibiotics to which they were formerly susceptible. Example: In the U.S. in the decade from 1985–1995, resistance of Shigella (which causes gastrointestinal illness) to ampicillin grew from 32% to 67%. And, while only 7% of these isolates were resistant to the combination of sulfamethoxazole and trimethoprim at the start of the decade, that figure had grown to 35% by the end of the decade.
Bacteria develop resistance by acquiring genes encoding proteins that protect them from the effects of the antibiotic. In some cases the genes arise by mutation; in others, they are acquired from other bacteria that are already resistant to the antibiotic. The genes are often found on plasmids which spread easily from one bacterium to another — even from one species of bacterium to another.

19. Antibiotics An antibiotic will attack a cell wall of a bacteria
Different antibiotics are engineered to attack different cell walls based on the peptidoglycan they contain.
“The walls of bacteria are made of a complex polymeric material called peptidoglycan. It contains both amino acids and amino sugars”

21. Infectious Animation