Micro Ch 3
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What are three prokaryotic traits?
- thick, complex outer envelope
- compact genome
- tightly coordinated cell functions
What are the basic compenents of the bacterial cell?
- cell membrane
- cell wall
- flagellum or other protrusions
What are the chemical components common to all cells?
- essential ions
- small organic molecules
What are the basic cell membrane components in bacteria?
- phospholipid bilayer
- tranporter proteins
- ATP synthase
What is a phospholipid?
Glycerol with ester links to two fatty acids and a phosphoryl head group, with various side chains.
Why can't cells stay in equilibrium?
ATP synthase is the main source of power for cells, and it requires a proton gradient to produce ATP
What is selective transport?
cell membrane is semipermeable, so it is selective in that not everything can move in and out of the cell
What is the different between passive and active transport?
Active transport requires energy, passive transport simply moves along the proton gradient.
What are hopanoids?
Planar molecules filling in the gaps between hydrocarbon chains (phospholipids).
What is the sacculus?
- The bacterial cell wall made up of PEPTIDOGLYCAN
- it provides shape, rigidity, and ability to withstand turgot pressue.
What is the structure of murein or peptidoglycan?
- Long polymers of two disaccharides called NAG and NAM which make up the spiral backbone
- Peptides branch off of NAM (L, G, D, L, L)
- To form crosslink, a tetrapeptide is formed by dropping an L (Alanine), connects two NAMs
What is D in the crosslinks?
- D is diaminopimelic acid, also called DAP
- it has a similar structure to LYSINE
- it is unique to peptidoglycan
What is a beta linkage and where is it found in peptidoglycan?
- A beta linkage is used for support, where as an alpha linkage is for energy storage (such as in starch)\
- NAM and NAG are linked with thought a beta linkage
How does penicillin work?
it blocks the formatino of the cross bridge/link
All of the following are parts of peptidoglycan except:
A. N-acetyl muramic acid
B. Diaminopimelic acid
D.(alpha)- 1-4 glycosidic linkage
E. Peptide linkage
D because the 1-4 glycosidic linkage is a BETA linkage
What are important characteristics of gram + bacteria?
- much thicker cell wall
- may have a slick capsule comprised of polysaccharides which prevent phagocitosis
- have teichoic acids for strength (specific to gm+)
- one membrane rather than two
What is specific to mycobacteria and what are the implications?
- mycobacteria have MYCOLIC ACID, very unique.
- -mycolic acid can be targeted in antimicrobials to eliminate these bacteria
- they have a very complex cell envelope which requires a large amount of time and energy to produce, so they are slow growing.
- -This means is take far more time to eliminate these bacteria because antimicrobials generally target stages of GROWTH
Which stain is used for Mycobacterium?
Gram negative characteristics
outer membrane with toxic Lipopolysaccharides and transporter proteins/porin
What are the three parts of LPS?
- Lipid A
- Core polysaccharide
- O polysaccharides
Which part of LPS is toxic?
Which part of LPS confers serotype specificity?
The O polysaccharides or O chains. Each one has different O polysaccharides; there can be multiple O chains in one species.
What are several examples of gram positive bacteria?
Step, Staph, Bacillus
What are several examples of gram negative bacteria?
Shigella, Salmonella, E. coli
Which of the following is only found in Gram positive bacteria?
B. Lipopolysaccaride (LPS)
D. Teichoic Acid
Both C and D are exclusive to gram positive bacteria
What color do gram negative bacteria turn with a gram stain and why?
It doesn't stain at all, because the thin cell membrane doesn't reatin the dye. It's then counterstained pink because the pink is a light enough color to not affect the darker staining of the gram positive bacteria.
What color do gram positive bacteria turn with a gram stain and why?
purple because the thick cell wall retains the crystal-violet
What is a nucleoid?
the region in prokaryotes that extends throughout the cytoplasm and holds the cell's genome
What is a flagellum?
a spiral filament of protein monomers called flagellin. It's rotated by a proton motive force
What is chemotaxis?
- slick outer coating that some bacteria have; made up of coat proteins.
- Prevents PHAGOCYTOSIS
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