6_26 Class Notes: History, Bacterial and Virus anatomy

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The Golden Age

Louis Pasteur: Fig. 1.11

 

Pasteur’s wine experiments: (1857) Fig. 1.14
 
Procedure developed which procedure that is still used today:

 

Pasteur’s Wine Results:
1-  Microorganism are capable of metabolizing

*2-  Microbes cause disease in humans (wrote Germ Theory of Diseases) not widely accepted
 
*3-  Microorganisms are not spontaneously generated
(* conclusions 2 and 3 questioned vigorously until later....) 
    
  *#2 and 3 were NOT accepted by scientific community, more later….
 
 
Pasteur’s S-Flask Experiments: (1865) Fig. 1.12

 
  * Government contest: Spontaneous Generation

* Heat to kill microbes, microgranisms appear only from air.

* use of open S necked flask silenced "vital principle" critics

(cured silk worm disease)
 

Pasteur’s S-Flask Results:

* Microorganisms do not spontaneously generate 

http://science.howstuffworks.com/innovation/scientific-experiments/scientific-method5.htm



 
Robert Koch-  Fig. 1.6
Koch’s Anthrax Experiments: (1875)

* Prussian (German) doctor
* Studied cause of anthrax in cattle
 

 

Figure 5: A German Leitz microscope (c. 1910) similar to the one used in Koch’s lab.⁶

http://www.answersingenesis.org/articles/aid/v5/n1/koch-creation-and-specificity-of-germs

 
Streptobacilli (chain and rod shaped)

Figure 2: Photograph of Bacillus anthracis, the cause of anthrax.³

Koch’s Anthrax Results:

* "proved" the germ theory of disease  (used solid medium to isolate pathogens)

                - (Anthrax caused by Bacillus anthroacis)
* techniques: Still useful
    - Postulates for causative agent ID
      * Modified for viruses- don't grow in culture
      * pure culture methods and staining methods
 
 
Koch’s Postulates:   Fig. 14.7

•  Step 1: find pathogen and isolate, sick animal has it but healthy does not have it.
• Step 2: grow pathogen in culture medium
• Step 3: cultured pathogen causes disease in healthy animal (inject into healthy animal to see if it gets sick.
• Step 4: reisolated pathogen same as the original pathogen

 
 

Pasteur/Koch Accomplishments

Pasteur

• 1857-wrote Germ Theory
• 1865- spontaneous generation disproved
• 1880-attenuation methods
• 1883-diptheria toxin effect
• 1885-rabies vaccine
• 1885-Pasteur Institute
• Died 1895

Koch

• 1875-proved Germ Theory
• 1880-pure culture methods
• 1882-ID cause of TB
• 1884-ID cause of diptheria
• 1883- ID cause of cholera
• 1884-treatment of diptheria
• 1885-1890- (found causative agent of many diseases)
• 1891-Director, Institute of Infectious Diseases
• 1895- TB vaccine trials fail
• Died 1910

Pasteur---Attenuation (1880):

* Weakening of pathogen to create a vaccine (this is where he got the money to start the Pasteur insistute)
 - Accidental discovered when he was studying chicken cholera. Old cultures used showed that the chicken didn't get sick. second experiment: half died but the other half did not because they were used in the first experiment and were injected with the weaker old cultures and didn't get sick in the first time.

  Discovered accidentally by whom doing what:

• Methods include: Aging culture
• Drying culture or tissue containing organism
•  example (* rabies- virus) 
• http://www.pasteur.fr/ip/easysite/pasteur/en/press/press-kits/rabies/louis-pasteur-and-rabies-vaccination
• Abdominal fat injection every day
• Exposure to weak acids
• exposure to other harch chemicals (formalin)
• Passage through animals (forced evolution to new host and would not cause disease in original host)

Alexander Fleming: (1929 and 1941)  Fig. 1.20

*PHD and MD
* Dirty dishes "accident"
Staph









http://www.medicinenet.com/antibiotic_resistance/page3.htm

http://suite101.com/article/dr-fleming-penicillin-and-the-penicillium-mold-a105258





**** Group Activity*****

Pair scientist together and explain if they worked together  or not and why.

Timeline:

1600-1700
Hooke and Redi
Leeuwenhoek/ Hooke worked together

Jenner 1796

Semmelweiss/ Lister

Lister/ Pasteur over lapped asceptic techniques and Pasteur's microbes did not work together

Pasteur/ Koch competed against each other


Flemming everyone else died

Topic 3a: Bacterial Anatomy

General prokaryotic characteristics: Table 3.5, 3.6

* Prokaryotic - simple
* No membrane bound organelles
* Unique features are "target" for drugs (see *)

(watch for * = targets for antibiotics to attack bacteria)  Fig. 10.2

Learn ONE example of drug from Chapter 10

Morphology and Arrangement:
Three basic shapes (morphologies): (Fig. 11.1, 11.6, 11.7)

• cocci - round
• bacilli - rods
• spirilli -

Arrangments:

• strepto-

• staphylo-

• diplo-

• other:

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All Bacterial cells have…
Fig. 3.2

(Standard parts found in bacteria)

• Cell membrane (Fig. 3.16)

                   - Phospholipid bilayer; lacks sterols found in eukaryotic cells

•  Cytoplasm

     - Water medium, Inclusion of lipid, starch etc. Iron chunks in some bacterial cycles that are magnetic

• Genome *
•  DNA double helix molecule
• one circular "chromosome"
•  http://www.cellsalive.com/cells/bactcell.htm
• 

                 * No nuclear membrane (nucleoid region)

http://www.nature.com/scitable/topicpage/major-molecular-events-of-dna-replication-413

• Ribosomes

                       Protein production ----
                          Size? 70S(small)* (S unit of size)    (ours are 80S in eukaryotes)
This means we can make drugs targeting ribosomes because its big enough difference between our ribosomes and bacteria's that you can attack them without interfering with our ribosome

Example drugs: Kanamycin, Tetracycline, Erythromycin Fig. 10.2 10.4

• Cell wall - peptidoglycan*   (Fig 3.13, 3.14, 3.15)
• NAG- N- acetyl glucosamine

• NAM: N- acetyl muramic acid

• tetrapeptides : cross linkage between NAG-N and NAM-N 

Wall exists in two alternatives:
Picture  gram positive/ gram negative

•  http://micro.digitalproteus.com/morphology2.php
•  
• Fig. 3.15
• 
  
•  Gram positive

Cell wall organized: thick peptidoglycan

Teichoic acids

• Gram negative 
• thin peptidoglycan
• outer LPS: Lipopolysaccharide
• Lipid A (endotoxins)

 Cell wall organized:

Additional outer “membrane”:

LPS layer

Lipid A

* ALL " -cillin" drugs attack the peptidoglycan linkages:
Stronger effect on gram + (poor penetration of LPS)

cells bursting because they take in water... affect the cell wall

example: Cefoelor


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Topic 3a: Bacterial Anatomy

General prokaryotic characteristics: Table 3.5, 3.6


(watch for * = targets for antibiotics to attack bacteria)  Fig. 10.2

Morphology and Arrangement:
Three basic shapes (morphologies): (Fig. 11.1, 11.6, 11.7)

• cocci -
• bacilli -
• spirilli -

Arrangments:

• strepto-

• staphylo-

• diplo-

• other:

---

All Bacterial cells have…
Fig. 3.2

(Standard parts found in bacteria)

• Cell membrane (Fig. 3.16)

•  Cytoplasm

  

• Genome *

• Ribosomes *

Size?

• Cell wall - peptidoglycan*   (Fig 3.13, 3.14, 3.15)
• NAG

• NAM

• tetrapeptides

• Gram positive

Cell wall organized:

Teichoic acids

• Gram negative

 Cell wall organized:

Additional outer “membrane”:

LPS layer

Lipid A