October 7th notes

October 7, 2009
LR1 Rough Draft Deadline: Friday October 16, 2009 by 5 pm. Email as .doc not .docx as attachment in email. ( must have 5 journal articles in lab report no text book)
Final LR1 October 30, 2009?
Bacteria live in a aqueous environment
Cell envelope stuff protect bacteria from osmotic pressure.
There is some turnover in cell envelope components
Bacterial cell walls make bacteria much more resistant to osmotic stress that eukaryotic cells can be. However if cell wall is broken down cell can exploded. (Compromised then bacteria are no more resistant to osmotic stress that our eukaryotic cells are)
I. Factors that influence bacterial growth rates
a. Osmotic(diffusion of water across a membrane) pressure and availability of water(how much water is present in an aqueous solution compared to the concentration of water in pure water, defined on a 0 – 1 scale zero being no water 1 being 100% water) (distilled water = 1.0, Blood = 0.95, ocean = .90, honey = 0.80) (E. coli prefer water availability of 0.95 and will be fine if dropped in a water availability into 1.0 and be fine. In sea water will loss some water but not hurt too badly. This is the same for virtually all bacteria that live in the human body. Bacteria that live in honey don’t make us sick so it doesn’t spoil and would die in our body.)
i. Halophiles – bacteria that live at low water availability. By having very high solute concentration inside cell, halophiles able to pull water into cell even when in very high water-poor environments.
ii. Why honey doesn’t spoil, and about rubbing salt in a wound -
b. Hydrostatic Pressure/atmospheric pressure
- Bacteria we usually come into contact w/ best adapted to 1 atm
- Some bacteria live at bottom of ocean, ect – these adapted to much greater hydrostatic pressures
c. Oxygen 20% in our atmosphere (toxic)
Antioxidant is a chemical that “soaks up” any free electrons this helps prevent damage to DN, proteins caused by electrons bouncing around and breaking DNA strands/altering protein structure
In aerobic respiration oxygen is the terminal electron acceptor.
Oxygen: is very electronegative(attractive to electrons)
So cell in environment with lots of O2 is also in presence of lots of e-s, e-s bounce around, break DNA, Proteins
Aerobic- environment cells (e.g. ours all bacterial cells that live in normal O2(~20% O2)
Must have mechanisms for fixing DNA and protein damage caused by e-s, O2
Was it always the case that the environment had 20% O2?
i. Anaerobes – can’t live in presence of any oxygen
1. Strict(cant survive with any O2) (ex. C. difficile) vs. facultative (can live with or without oxygen) (ex. E. coli)
ii. Aerobes – Requires O2 to grow
• Use identical ATP-generating mechanism (w/ O2 as terminal electron acceptor) as our mitochondria do
• No oxygen means not ATP generation possible
• Most skin normal flora are aerobes (ex. staphylococci)
iii. Other atmospheric requirements
1. Microaerophiles – Must have ~ 5% oxygen to grow, but die with more O2 than that
2. Capnophiles – Must have some O2 and 5-10% CO2 to grow  (almost all pneumonia causing bacteria)
Why does oxygen inhibit the growth of many kinds of Bacteria? Why do other kinds of bacteria and your mitochondria need oxygen.
d. Temperature
i. Psychrophiles – grow best at about 5*C to 10*C – die at warmer temperatures – heat denatures proteins and kills cells
• Lots of unsaturated fats in membranes
• Little G+C, lots of A+T in DNA
• How can I divide
ii. Mesophiles – Bacteria that grow best between 20*C and 35* - 45*C – all bacteria that live in our bodies pretty much have to be Mesophiles.
iii. Thermophiles – any bacteria that live best at 60*C (hot enough to give someone like me a nasty burn) & hyperthermophiles – Bacteria that live best at a little above 100*C
• Have mainly saturated fats in their membranes
• Have lots of G and C and little A and T in DNA Bonded ot T
• How can I keep my cell together
• Take more energy to break a G and C bond than it does Between A and T because G is triple bonded to C and A is only Double Bonded to T
Higher temoeratures Have More G and C
If liquid water is present something can grow there. The temperatures we are aware of that cause water to be something at some temperature differ in different parts of the earth. Low to high
Unsaturated fats more flexible at lower temperatures
e. pH
i. acidophiles – Bacteria that live best at low pH’s (1.0 – 3.0)
• cause stomach ulcers (H. pylori)
ii. alkalophiles – Bacteria that live best at high pH’s (10 +)
Internal pH of all acidophiles, alkalophiles ect. Is ~ 7.0
Look up * toxic Shock Syndrome. Whats relation to Having
- Aerobic
- Anaerobic
- Vaginal Normal Flora
- S. Aureus
f. Competition from other microbes; predation by phages and by other bacteria
Note: As long as there’s liquid water, some kind of prokaryote can thrive in practically any environment.
Note: For bacteria to cause disease in humans, that kind of bacteria must be able to grow in the human body.
Do you have to worry about an epidemic caused by bacteria from Mars?
TOXIC SHOCK – discussion today!
Shock:
High Fever
Low Blood Pressure
Nauseam dizzinesss, fainting
Generlized pain
Organ failure
Septic shock caused by bacteria growing in blood stream = septicemia
Inflammation = general response to injury goal: get immune system cells to injury sitr
1) Blood vessel cells shrink, making vessels in area of injury leaky
2) Increase blood flow to site of injury
3) Release chemicals that send a pain signal ouch to my brain to tell me not hurt myself again
Bacterial components that  inflammation
• LTA
• Lipid A of LPS
• Super antigens: a bunch of different bacterial molecules that kick off an even more aggressive inflammatory even more so than LTA or Lipid A do.
Gram negative bacteria in patients blood(LPS lipid a causes inflammation)
Super antigens:
Ex. Toxic Shock Syndrome Super Antigen 1 (Toxin – 1) (TSST-1)
• Produced by some S. aureus