6_27 class notes: Bacterial Anatomy cont.

Review from yesterday: diagram of bacterial cell (gram + and Gram -) differences

Optional parts found in some bacteria:

Plasmids are extra bits of information and not required for cell functions. 

Optional parts: Plasmids

 *Small "extra" segments of DNA

* Generic

* Self replicating

* Easily passed

* (flash drive compared to hard drive) 

r Plasmids = Resistance to antibiotics

* 3 Common Mechanisms of antibiotic resistance coded for on r plasmids: 

        - Efflux pump pumps out drug

        - Enzymes break down drug 

        - Enzymes change drug

f plasmids = fertility genes
     - initiate conjugation
     - make sex pili 


t plasmids = production of toxins

Common combined plasmid (picture example)

(one of the reasons diahrea is that it eases transmition of organism to others)

***draw plasmids in diagram***

**hairy stuff**

Sex Pili (Fig. 3.11)

Appearance:

hollow tube that contracts down upon itself pulls them together. only contruct when there was another bacteria that did NOT have the plasmid. s positive, s negative... surface molecule that indicates that they do or don't have it..

        Function: temporary (directions on F plasmid) 
                    - tubular pilin protein, contracts
                    - connect cells: allow DNA transfer
*Do not limit to just one partner: picture of 1 s positive giving plasmid to three s negative cells.

Fimbrae (Fig. 3.10) made of pillin protein

Appearance: short and numerous; proteinaceous

Function: for adhesion to surfaces
example: gonnorhia ... clean cervice (women).. urethra (men)

http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0004526/

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Flagella (Fig. 3.6)

Appearance: hairlike structures
       - Stiff, curved 
       - rotate
                * counterclockwise = runs (positive simulus: food, good environment) 
                * clockwise = tumbles (negative such as toxin, bad environment)

Function: movement

Fig. 3.9

Run:  Flagellum moves in __counterclockwise_________ direction, bacterium moves ____quickly towards__________

Tumble:  Flagellum moves in ___clockwise_____ direction, bacterium moves _____away__________

Taxis: (chemo, photo, etc.): movement in response to stimulus
* more runs, fewer tumbles if detect positive stimulus ahead
* Fewer runs more tumbles if detect negative stimulus ahead.
 

Flagellar Arrangements: (Fig. 3.7)

Four common arrangments:

• lophotrichous - tuft..... Lopho "tassle"

• monotrichous -One flagellan all by itself........ mono = "one" 

• peritrichous -surrounding......... peri = all over exterior

• amphitrichous -both ends.........."amphi" = "both"

*** Gloey stuff**

Glycocalyx (Fig. 3.5)

Mucoid layer:
   - polysaccharide or glycoprotein

thick yellow, green, cloudy mucus = bacterial infection and not thin clear like your bodies natural response to a virus or allegries...

• slime layer = loose layer

• capsules = dens, thick layer

• biofilms = shared layer, many cells

Advantages of Glycocalyx/Capsules/Biofilms

• Confer increased pathogenicity, or help with survival:

1-neutralize drugs

2- fool/ delay immune response (capsule first)

3- adhere to surfaces

4- avoid phagocytosis (White blood cells eating of cell) 


Help cell survive:

 5- nutrient source during starvation

 6- storage of toxic wast products

Endospores (Fig. 3.24) gram positive?

* dormant, non-reproductive structures
* formed inside cell in bad conditions        

 Sporulation process: cell creates an endospore

* layers of petidoglycan + protein = spore coat
* water removed
* Dipicolinic acid added- heat stablity

Spore coat composed of: petidoglycan

spores contain decreased amounts of:
spores contain high amounts of:

Highly resistant to harsh environmental conditions:

• heat (survive boiling)
• harsh chemicals (alcohol, etc.) 
• drying
• lack of nutrients

Germination in favorable conditions to normal vegetative cells.

·         Germination: spore to cell

Endospore structure and types:
          * Bacterical spores are used to help identify the species by using three characteristics:

1. location
2. size 
3. shape

Anthrax picture: Endospore (central and oval), rectangle shaped
*******oval large central endospore: green, pink.. force dye in spore? learn how to do it in lab*****


 ______________________________________________________________________________________________
 *Review of drug targets discussed earlier  Figure 10.2
- attack ribosome
- cell wall synthesis
- DNA or RNA synthesis
*ADDITIONAL DRUG TARGET-block enzyme

__________________________________________________________________________________________________

Unusual Bacteria:

·         Archaea  Fig. 3.26, 3.27

• ancient
• not "true" bacteria
• Cell wall has NO peptidoglycan (protein) 
• Simpler than bacteria (have hooks and not a lot of other things that bacteria has) 
• methanogens
• extremophiles
• thermophiles (hot temperatures)
• halophiles  (salty environments)
• geothermal rift (archaea bacteria located) 

·         Mycoplasma Fig. 11.15

• Some pneumonias (e.g. "walking" pneumonia)
• no cell wall (can't survive if NOT in host tissue)

·         Rickettsia and Chlamydia Fig. 21.1, 21.6

• Rocky Mountain Spotted Fever (Rickettsia) more come in NC then anywhere else in the world... rapid progressing disease...
• Chalmydia: eye or venereal disease
• replicate only inside host cell, burst out to infect new cells

• Spirochaetes Fig. 3.8

• Borrelia = lyme disease
• treponema = syphilis
• HUGE spiral cells
• axial filament of internal flagella for motility ( drills through tissue because the WHOLE cell turns not just the flagella to move)

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Bacterial Growth

Bacteria Reproduce by Cloning...

• binary fission (Fig. 6.18, 11.2)= splitting in two.

• genome is copied.
• bidirectional 
• topoisomerase fixes supercoils
• Cell elongates
• new cell wall and membrane separates the new cells.

• generation time= time between divisions

 **************

 group activity? 

* Ten bacterial cells were introduced into a test tube. In an hour, there are 80 cells present. What is the generation time of this particular species of bacteria? 

 10 >>> 20 >>> 40>>>80

divides 3 times in 60 minutes... 60 min/3 = 20 minutes

Generation time = every 20 minutes

Bacterial Growth Curve (Fig. 6.19, 6.21)

• Lag phase -

• Exponential growth phase -

• Maximum stationary phase -

• Exponential death phase -

• Minimum stationary phase OR crash