Synthesis and assembly
Molecular composition of E.coli
Precursors to the monomers
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
-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
-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.
molecules diffuse into the periplasm. Phosphate in the periplasm most likely be utilized by that cell,
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,
Friday, September 30, 2011
MIC140 Page 1