Lecture 4 5 6 7 8 9 10

Lecture 4 5 6 7 8 9 10 - Lecture 4 Friday, September 30,...

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Announcements Cellular organization II. Cytosol a. Envelope b. Synthesis and assembly III. Overview a. Molecular composition of E.coli b. Precursors to the monomers c. Where does the cell expend the energy? Think about metabolism as generating energy for organization. Bacteria are much more diverse. The cell organization The cell: consist of two compartments All cells must have a cell membrane Original compartment was inorganic, calcium, etc. something to hold inside reaction from outside, that’s what the membrane does, keeping small molecules inside…as well as other small molecules outside. Concentration gradient: high inside ---> low outside. Cell membrane: separate outside from inside. Cytosol: where all the reactions take place. -Nucleoid: confined in the cytosol: we can see the structure -Bunch of little dots which are the ribosomes, invariable. -Inclusion: larger than ribosomes, just something there. -Carbon can be stored by bacteria: as glycogen, polyhydroxybutyrate, phosphate- polymerizes to make polyphosphate. Experimentally: we label with radioactive phosphate. Phosphate can serve as an energy source in times of starvation, cells can utilize polyphospahte. -Nitrogen- stored by cyanobacteria, cyanophycin and aspartate arginine -soluble stuff Envelope: -peptidoglycan or murien sacculus. Lack of peptidoglycan can cause osmotic shock, water will flow in since its concentrated more inside the cell. Oligotrophs: nutrients concentrations are low so very stiff walls. It also gives the shape of the cell, circular, ovoid, rod, or long filament---all dictated by the peptidoglycan---very dynamic. -Outer membrane: outside the covering the peptidoglycan layer. Difference between gram neg and pos. this yeilds the periplasm which is the space between outer membrane and plasma membrane. It really dictates how a cell interacts with its environment. Bacteria get inorganic phosphate or organic phosphate, R-PO4 --- hydrolyzing this bond with phosphotase. Phosphotase: alkaline and acid. Gram negative : If this bacterium produces alkaline phosphotase, the alkaline pphosphotase will end up in the periplasm. In that space it'll carry out the reaction, the organic phosphate molecules must be able to penetrate to the periplasm, so it means there must be pores in the outer membrane. Porins: small molecules diffuse into the periplasm. Phosphate in the periplasm most likely be utilized by that cell, selfish metabolism. gram positive: If there is no outer membrane, the alkaline phosphate goes out into the environment to the neighboring cells. Membrane: looks like conventional lipid bilayer Outer membrane: Notebook. Assymetric structure. The polysaccharide coming off the bilayer can cause specificity. It has LPS attached to outer membrane, Lecture 4 Friday, September 30, 2011 9:59 AM MIC140 Page 1
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-In the PM, there are proteins sticking out which are called fimbrae (cilia): motility, excretion, syrenge, entry points esp for phage. Often phage will attach to these fimbrae.
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Lecture 4 5 6 7 8 9 10 - Lecture 4 Friday, September 30,...

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