Block One Lecture 6
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The only family that lacks it is __.
What is the function of the cell wall?
- prevent osmotic lysis
- Purrell could've damaged membranes of bacteria, but not every bacteria in our lab.
Base structure of cell wall in gram positive bacteria
polypeptide that link large polymer backbones made of NAM and NAG, which are rigid strong peptides
peptide side chains and ridges; little proteins in a gram positive that make the cell wall strong; gram negative only has one layer and none of the fancy proteins located in the gram positive
polymers are woven up and down and horizontally, nice and tight, giving it resilience
lipotechoic acids that anchor them in the cell
Base structure of cell wall in gram negative bacteria
There's two plasma membranes; outer plasma membrane and inner plasma membrane
In between is the periplasmic space with a very thin cell wall; no techoic acids or peptides woven together
nothing to keep CVI in there
- Large spaces between the polymeric backbones, allowing things
- still have NAM and NAG but not many
Compare the two: Positive and Negative
Positive: crystal violet-iodide complex can't get out because too large; large stacks of polymers are woven up and down and horizontal; nice, thick, and tight; lipotechoic acids anchor cell wall to plasma membrane of the cell; thick, strong structures in gram positive
Negative: there's two plasma membranes-- outer and inner, and periplasmic space, which has a thin cell wall; no cool peptides, techoic acid, no weaving together; nothing to keep CVI in there; large spaces between polymeric backbones.
Quick summary between gram positive and gram negative:
techoic acid present/ not present
only a couple of species have mycolic acid like Mycobacterium tuberculosis. They also have NAM and NAG; outer plasma membrane with all the action in front
Gram negative: lipopolysaccharides
- Lipid A anchors into the outer membrane
- O-polysaccharide projects away from the membrane and elicits a physiological response
- they have endotoxins (characteristic of gram- negative bacterial components)
Explain gram negative bacteria
characteristic of gram negative components
- - not species specific
- - only released when celles die (when they die and get hit with LP A, it leads to potent conditions
- # one cell type you carry around is E. Coli --> more than red blood cells
Unlike exo toxins, __ is highly dose dependent.
Gram stain mechanism
iodine acts as a mordant and creates a larger complex
- in Gram negative, alcohol dissolves the membrane and CVI washes away. Counterstaining with safranin keeps it pink
- In gram positive, the peptidoglycan dehydrates, causing the cell wall to restrict and thus cause CVI to stick in
Atypical Cell Walls
- some are wall less
- bulk of them have cell walls for structure, etc. but not made of NAG and NAM
- (abnormal cell wall that functions as one)
mycoplasma: bacterial family commonly on skin--> contaiminates alot
- --> lack cell walls
- --> Most bacteria are monomorphic, but, their shape changes with the environment--> pleomorphic
--> have sterols in the plasma membrane (bacteria don't and neither do archaea)
Damage to the Cell Wall
penicillin inhibits NAM and NAG from linking
- have __
- acts as __
- some hydrophobic tails tend to be __ and __
- __ help flip flopping
- enzymes for __ (__ in eukaryotes; in bacteria, all processes occur where?)
- - the same parts
- - barrier
- - shorter and more unsaturated
- - flipases
- - ATP production; mitochondria; on the inner membrane (on the iner leaflet)
Some bacteria form __, which are __ products.
- All pigment productions occr at __ in the cell (__)
Bacteria have __.
- Can undergo __.
- For gram positive, what happens?
classic transport proteins
Gram positive: water is taken up; the molecule bursts due to its lack of NAM and NAG
most are protein based structures
not much energy reserve; very little
produce H2O gas and rlease it (gas vacuoles)
Carboxysomes are bacterial microcompartments that contain enzymes involved in carbon fixation.Carboxysomes are made of polyhedral protein shells about 80 to 140 nanometres in diameter.
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