z-MicroBio Final – Old Material

Koch’s Postulates
1. The suspected pathogenic organism should be present in all cases of the disease and absent from healthy animals

2. The suspected organism should be grown in pure culture away from the animal’s body

3. Such a culture when inoculated into susceptible animals, should initiate the characteristic disease symptoms

4. The organism should be reisolated and shown to be the same as the original

Gram + vs Gram –
IV Assembly Reactions
Assembly Reactions involve the chemical modification of macromolecules, their transport to pre-specified locations in the cell, and their association to form cellular structures:
Envelope, appendages, nucleoid, polysomes, inclusions, and enzyme complexes.
In some cases, other macromolecules must aid in the process-Directed Assembly
III Polymerization Reactions
Polymerization Reactions consist of the directed, sequential linkage of activated molecules into long (sometime branched) chains.
All the macromolecules are formed from the building blocks that include 20 amino acids, 8 nucleotides, numerous sugars, and fatty acids
Polymerization of building blocks into proteins, RNA, DNA and glycogen occur inside the cell, whereas the final steps of their assembly into lipopolysaccharide, capsule, and murein occur outside the cell membrane
Amino acid  polypeptides
Nucleotides  nucleic acids (RNA or DNA)
Monosaccharides  polysaccharides
Fatty Acids + Glycerol + Phosphate  phospholipids
II Biosynthetic Reactions
Biosynthetic Reactions produce the building blocks of polymerization reactions; they also produce cofactors and related compounds including signaling molecules called Alarmones. The hundreds of biosynthetic reactions are grouped into functional units called Biosynthetic Pathways each consisting of from one to a dozen sequential reactions that produce one or more building blocks.
Biosynthetic pathways may be linear, branched, or in some cases, interconnected; each pathway is controlled en bloc.
I Fueling
Provides 3 things for the cell
Energy (from oxidation of energy source in a complete oxidation-reduction reaction)
“C” skeletons: 12 intermediates
Reducing Power: ex NADH + H+
The pathways of catabolism have a G = (-) and are spontaneous
Nt = N0 x 2n
Nt= log10 Nt –log10N0 / .301
g = t/n
g = .301t / log10 Nt –log10N0
k = 1/g or n/t
k= log10 Nt –log10N0 / .301t
= N0 x 2n
= log10 Nt –log10N0 / .301
= t/n
= .301t / log10 Nt –log10N0
= 1/g or n/t
= log10 Nt –log10N0 / .301t
Direct Microscopic Count
Number of mo’s/mL in a suspension = (Avg # of mo’s/field) x (Microscopic ffactor) x (Dilutions factor)
Microscopic factor (MF) = Area of the film (Af)/Area of the microscopic field (Amf)
MF = Af r2
Amf r2
The ABC System
Anaerobic Respiration Electron Acceptors
Biological oxidation in which the terminal electron acceptor is usually an inorganic molecule (external) other than oxygen.
Uses oxidative phosphorylation for ATP synthesis
Some of the electron acceptors used include nitrate, sulfate and carbon dioxide.
When carbon dioxide is used as an electron acceptor, the resulting product is either methane or acetic acid, depending on the organism involved. Much if not all the methane produced in our gut or by cows or in swamps is produced by this process.
Aerobic Respiration
uses oxygen as a terminal (external) electron acceptors
Pyruvate (3C) is oxidized to acetyl-CoA (2C) which enters the TCA (Krebb’s) cycle by condensing with the 4 C oxaloacetate to produce citric acid
4 moles of NADH & 1 mole of FADH2 are produced per pyruvate
Since there are two pyruvates per starting glucose, this produces 30 net ATP
When the two SLP ATP are added from the EM pathway and the NADH goes to electron transport to produce 3 X 2 = 6 more. These add to the 30 to give 38 total ATP per prokaryotic cell
Certain species of Bacteria produce special structures called endospores within their cells
Are resistant to heat, drying, disinfectants, acid and radiation
Can remain dormant for extremely long periods of time
Endospore-forming bacteria are found most commonly in the soil. Most notable genera include Bacillus and Clostridium
Faraday’s Equation:
G = -n F E
Phospholipids consist of hydrophobic fatty acids esterified to glycerol (a poly-hydroxy alcohol)
The phospholipids spontaneously form a bilayer with the hydrocarbon chains of the fatty acids pointing inward toward each other (hydrophobic attraction) and the hydrophilic portions remain exposed to aqueous environment or internal to the cell
Categories: Microbiology