1. Bacteria v Virus

2. Structure of a Bacterial Cell
Cell Wall
-maintains cell structure
-composed of peptidoglycan, a polymer of sugars and amino acids
Plasma Membrane
phospholipid bilayer
Nucleoid
The region DNA is found in prokaryotes
DNA
A single double-stranded circular chromosome
NO histone proteins
Plasmid
small circular chromosome
may carry an antibiotic resistance gene
Flagella
-tail-like structure used for locomotion

3. Features of an Infectious Bacteria
capsule: surrounds bacterial cell wall; protects bacteria from phagocytosis
pili: allows bacteria to attach to and invade other cells despite mucous and cell-turnover
enzymes: break down matrix between cells allowing bacteria to spread throughout tissues

4. Bacteria create Toxins
exotoxins:
cause lysis (breakage) of specific host cells
enterotoxins:
cause secretion of fluid into the small intestine leading to vomiting and diarrhea
endotoxins:
cell-bound lipopolysaccharides; causes fever and inflammation

5. Bacterial Transcription and Translation is quicker then eukaryotes
Fast Reproduction
Bacterial Transcription and Translation is quicker then eukaryotes
Reproduction occurs independent of host cell
Life Sciences-HHMI Outreach. Copyright 2008 President and Fellows of Harvard College.

6. Bacterial Illness: Strep Throat
Infectious agent: Streptococcus pyogenes
spherical bacteria usually found in pairs or chains
most sore throats are actually caused by viruses and are NOT considered strep throat (~15-35% are strep throat)
symptoms: sudden, severe sore throat, fever over 101°F, swollen tonsils and lymph nodes, white or yellow spots on the
back of a bright red throat
transmission usually by air-born bacteria
incubation period prior to symptoms 2-5 days
diagnosed with a throat culture and detection of strep-specific molecules
treated with antibiotics, usually penicillin for 10 days

7. Antibiotic Treatment of Bacterial Infections
antibiotics kill bacteria or prevent bacteria from dividing
antibiotics are produced naturally by bacteria and fungi
antibiotics are mass produced by growing huge cultures of the source microbe
Why might microbes produce antibiotics in nature?
Staphyloccocus aureus
antibiotic
Life Sciences-HHMI Outreach. Copyright 2008 President and Fellows of Harvard College.

8. Antibiotics: Mechanisms of Action
Inhibition of Bacterial Protein Synthesis
- some antibiotics bind to the large or small subunit of the bacterial ribosome
Examples: neomycin, streptomycin, azithromycin, erythromycin, tetracycline
Life Sciences-HHMI Outreach. Copyright 2008 President and Fellows of Harvard College.

9. Antibiotics: Mechanisms of Action Inhibition of Cell Wall Synthesis
-some antibiotics prevent peptidoglycan formation
Examples: vancomycin, amoxicillin, ampicillin, penicillin
Life Sciences-HHMI Outreach. Copyright 2008 President and Fellows of Harvard College.

10. Animation of Antimicrobial Resistance

11. single stranded OR double stranded RNA or DNA
Properties of Viruses
Basic Structure
single stranded OR double stranded RNA or DNA
protein shell capsid
some have a lipid bilayer with embedded proteins
Host Cell
Influenza
Life Sciences-HHMI Outreach. Copyright 2008 President and Fellows of Harvard College.

12. Virus Life Cycle and reproduction virus attaches to host cell
Properties of Viruses
Virus Life Cycle and reproduction virus attaches to host cell
virus enters cell via endocytosis
capsid degraded
host transcribes viral DNA
host ribosomes translate viral RNA
new viruses assemble
Host Cell
Life Sciences-HHMI Outreach. Copyright 2008 President and Fellows of Harvard College.

13. Viral Illness: The Common Cold
symptoms: sore throat, runny nose, nasal congestion, cough
prevalance: 3 colds/ person/ year
incubation period 2-5 days
no cure for the common cold (or the flu)
Life Sciences-HHMI Outreach. Copyright 2008 President and Fellows of Harvard College.

14. Rotavirus is a virus that causes gastroenteritis (inflammation of the stomach and intestines).

15. Why don’t antibiotics work for viral infections?
Bacterial vs. Viral Infections
Watch Video
Why don’t antibiotics work for viral infections?
MicrobeLibrary.org; © Jean-Yves Sgro, University of Wisconsin
Polio Virus
Streptococcus
Life Sciences-HHMI Outreach. Copyright 2008 President and Fellows of Harvard College.

16. Bacterial Infections Viral Infections
strep throat
gastroenteritis
cholera
tuberculosis
food poisoning
botulism
gangrene
necrotizing fasciitis
boils, abscesses
pneumonia
acne
meningitis
ulcers
the flu
colds
AIDS
hepatitis
chicken pox
gastroenteritis
measles
mumps
E. Bola
pneumonia
West Nile
cervical cancer
Life Sciences-HHMI Outreach. Copyright 2008 President and Fellows of Harvard College.