1. PATHOGENS Agents that cause disease bacteria, viruses, fungi, and protists

2. BACTERIA
STRUCTURE
All unicellular, smaller than typical eukaryotic cells but visible with the light microscope
A. SHAPES
1.) cocci (round)
2.) bacillis (rod)
3.) helical
a. spirilla (short, rigid)
b. spirochetes (long, flexible)
may be single, paired, clumps, or chain
*Shape is the first clue for identification

3. Cell structure

4. Cell Structures no nucleus one circular chromosome
ribosomes in cytoplasm (no membrane-bound organelles)
have cell walls, sometimes double
(Eubacteria: cell walls of peptidoglycan)
some produce spores in harsh environments (killed by autoclave at 121o C)
some have flagella (they are mobile)

5. Reproduction Nutrition Respiration asexual – binary fission
However, possible transfer of genetic information called transformation – DNA uptake from the environment
Nutrition
Photoautotrophs – makes food with energy from light
Chemoautotrophs – makes food with energy from chemicals
Heterotrophs – energy from other organisms
Capable of both (heterotrophic and autotrophic)
Respiration
Aerobic, anaerobic or facultative (can be either depending on environmental conditions

6. BENEFITS OF BACTERIA 1. Food production - pickles, cheese, yogurt
2. Drug production – ex. human insulin, growth hormone
(genetic engineering)
3. Digestion – ex. E. coli in humans(also vitamin K absorption)
4. Decomposers – major nutrient recyclers in every ecosystem
5. Nitrogen fixation – Transfer of N2 in air into nitrates in the
soil. Important plant nutrient.
-Rhizobium symbiotes on legume root nodules
fix nitrogen in soil. (carnivorous plants)
6. Scientific research – ex. Transformation experiments
7. Natural pesticides
8. Some antibiotics – many from soil bacteria
called actinomycetes
9. Bioremediation – use of bacteria to remove pollutants
from soil, water, air ex.s sewage treatment, oil spills

7. Bioremediation of sewage
at an oil spill

8. HARM FROM BACTERIA 1. Poisoning
a. Endotoxins - part of some bacteria cell walls
ex.s Salmonella
b. Exotoxins – toxins secreted by bacteria
Ex 1) Botulism – toxins produced by anaerobic fermentation in improperly canned foods
Ex 2) cholera – E. coli in contaminated water (shows up during war and famine)
fecal coliform test – water quality test for level of fecal bacteria in rivers, etc.
2. Pathogens – disease causing organisms
ex. meningitis, pneumonia, syphilis, TB, etc.
3. Tooth decay
4. Bioterrorism

9. Diseases Refer to the following handouts:
Bacterial Diseases and Modes of Transmission
Viral Diseases and Modes of Transmission
Known routes of HIV transmission
Menacing Microbes

10. Diagnosis Technique: Gram staining
Gram stain – clinical method for identifying bacteria
Results:
Gram + (violet after staining)
simple cell wall of thick peptidoglycan
less dangerous, easier to treat
Gram – (pink after staining)
more complex, 2 layer cell wall
less peptidoglycan and a layer of lipopolysaccharide
more resistant to antibiotics (outer membrane extra protective layer)
lipos. often toxic

11. Examples: Gram stain

12. TRANSMISSION/vectors
contaminated food
water
air
pests – ex.s insects, rodents
open cuts
human contact:
sexual
blood
hands

13. CONTROL: PREVENTION AND TREATMENT
1. good hygiene – brush teeth, wash hands
2. antiseptics
3. pest control
4. condoms/abstinence
5. vaccine – infection with mild, nonvirulent form of a disease produces antibodies that will attack virulent forms of the same disease at exposure.

14. PREVENTION AND TREATMENT
6. Antibiotics – take them all
7. Food precautions
a. preservation
- refrigeration, canning, freezing
- natural preservatives
include salt, sugar, vinegar (acids)
- synthetics ex. nitrites
b. pasteurization – method of repeated heating and cooling sequence to kill microbes in milk.
c. cook thoroughly

15. Viruses Nonliving DNA or RNA and a protein coat STRUCTURES:
Ex. 1) bacteriophage - attack bacteria
Ex. 2)
Flu virus

16. The lytic cycle – how viruses attack cells and reproduce

17. Viral diseases Disease/vector Symptoms/treatment
Dengue fever – mosquito Colds (rhinovirus) – airborne Flu – airborne
Hemorragic fever/ tawa tawa plant