Biol 120 Exam 2.txt

• Kills bacteria
• Viable count is less than total count

• Stops bacteria from reproducing
• Viable count and total count plateau

• Bacterial cells burst
• Viable and total count are similar. Both decrease.

• External Use
• -Sterilants
• -Disinfectants
• -Sanitizers
• -Anticeptics

Used on inanimate objects

• - lipid solvent, denatures proteins in membrane
• - Disinfectant

• - Qaurternary ammonium compounds (disrupt lipids in membranes)
• -Disinfectant or Sanitizer

• - Denature proteins and DNA
• - Disinfectant

• - Iodine, effects tyrosene so effects proteins (can be topical solution)
• - Disinfectant

• - effects SH groups so targets cystene and glutamine
• - Disinfectant

• - Denatures proteins
• - Disinfectant

• - Chlorine compounds are oxidizing agents
• - Disinfectant or Sanitizer

• (where you can’t use heat/radiation/filtration)
• - gaseous sterilants-Ethylene oxide, formaldehyde, peroxyacetic acid or hydrogen peroxide vapor
• - liquid sterilants- sodium hypochlorite, amyl phenol

• -handwashing
• -treating surface wounds

Ability to kill microbes. Depends on microbial load, amount of microbes present

• -surface attached communities
• -single species or multiple species (polymicrobial)
• -form when nutrients are plentiful and dissolve when conditions poor (individuals detach to find new sources of nutrients)
• -environmental signals

• Pseudomonas- cystic fibrosis (lungs)
• Staphylococcus- catheters and medical valves
• Polymicrobial plaque on teeth
• Marine snow- suspended particles of biofilm in ocean

• Planktonic cell adheres to surface
• Secretes polysaccharides
• Cell proliferation
• Send chemical signals (Quorum sensing)
• Attracts other bacteria
• Triggers genetic change in those bacteria so they join biofilm
• Exopolysaccharide (extracellular matrix of polysaccharides)
• Large colony is formed

• 1- Attach to surfaces
• 2-Protect the bacteria from host immune defenses.
• 3- Are highly resistant to antibiotics

• -chemical agents that can be used internally
• - must depend on selective toxicity so host cell isn't harmed

• Growth factor analogs
• Quinolones

• Broad spectrum
• Narrow spectrum

• Kill range of microbes
• ex. Gram negative AND Gram positive
• ex. Kill needed microbes in your body along with infectious microbes

• Kill just one group of organisms, however there is more chance of resistance
• ex. Kill only Gram negative

• Antibiotics
• Bacteriocins
• Toxins
• Bacteriolytic enzymes

Ribosome synthesized proteins formed by bacteria or archaea to kill closely related microbes.

• Bacteriocin
• Cause pore in cell membrane, disrupts proton motive force, allows ion influx
• Can also attach nucleic acid activity if it enters cell

• Bacteriocin
• Small heat-stable cationic proteins
• Cause pores that cause cells to leak

• 1. inherent resistance-lack the structure that the antibiotic inhibits
• 2. may be impermeable to antibiotic
• 3. alter the antibiotic to an inactive form (ex. Beta Lactomase)
• 4. modify the target of the antibiotic (mutation changes target so no longer recognized by antibiotic)
• 5. may develop an alternative biochemical pathway
• 6. pump out antibiotics entering the cells

• - energy released that can be used to do work
• - ΔG°’ -release of free energy-exergonic
• + ΔG°’-requires energy-endergonic

• - increase the rate of reactions 10¹² fold
• - protein catalysts
• - specific, bind via weak bonds
• - some require energy (ex. ATP)

• a. prosthetic groups
• b. coenzymes

• Tightly bind to enzyme
• ex. heme

• Loosely bind to substrate
• ex. NADH, FADH₂, Chymotrypsin

• oxidation
• LEO- loss of electrons
• oxidized
• electron donor
• reduction
• GER-gains of electrons
• reduced
• electron acceptor

• -tendency to become oxidized or to become reduced
• -more negative reduction potential donates electrons
• ΔE°’-difference in potential
• ΔE°’ is proportional to ΔG°’

• Less electronegative than H₂: negative redox potential
• More electronegative than H2: positive redox potential

Although fluorine is the most electronegative atom, it has properties that prevent it from being an electron acceptor

• Strong reduction potential: -.32V
• 2 electrons & 2 protons donated to destroy double bond
• NADP+ has a phosphate bond

• transfer of electrons from donor to acceptor through intermediary (also source of protons)
• 1) freely diffusible
• 2) attached to enzymes in cytoplasmic membranes

• ATP is a great source of energy
• ADP is a good source of energy
• AMP is a poor source of energy

• 1. Fermentation
• 2. Respiration
• 3. Photoheterotrophy

-partial breakdown of organic food without net transfer of electrons to a terminal electron acceptor

-breakdown of organic molecules with electron transfer to a terminal electron acceptor

-energy from light absorption is used to breakdown an organic molecule

• Lipids
• Glycerol (glycolysis)
• Fatty acids (oxidative breakdown to acetyl group)
• Amino acids
• Decarboxylation (glycolysis)
• Deamination (excretion)
• Aromatic compounds (acetyl groups- TCA cycle)

• ATP is synthesized during the catabolism of an organic compound
• Transfers high energy bond from one group to another, converting loe energy bond to high energy

• NAD+ reduced to NADH
• Consume ATP, produce 3 ATP
• Pyruvate
• (all happens twice)

• There are 10 variatios in archaea & bacteria
• Pyruvate is completely oxidized to CO2
• Can sometimes go backward for making carbon skeletons
• Intermediate molecules can be used for other processes

• Citric Acid Cycle Precursor Molecules
• -glutamate -> other AAs
• -oxaloacetate-> asparate -> other AAs

Can be used to make alanine

• Citric Acid Cycle Precursor Molecules
• Can be used to make serine

Pyruvate + 4NAD+ + FAD --> 3CO2 + 4 NADH + FADH2

• 8 NADH = 24 ATP
• 2 FADH2 = 4 ATP
• 2 GTP = 2 ATP

• Each level of chain is reduced by the product of the previous form
• ATP synthase uses proton gradient to make ATP

B) ethylene oxide

B) biofilms are more sensitive to antibiotics

C) filtration

• 1. Glycolysis
• Glucose -> 2 Pyruvate

• 2. Tricarboxylic Acid Cycle
• 2 Pyruvate -> 6 CO₂

• 3. Electron Transport Chain
• 12 H⁺ + 3 O₂ -> 6H₂0

• -transfer hydrogen atoms from NADH
• -inner surface of cell membrane
• -in respiration, hydrogen atoms passed to flavoproteins

• -riboflavin (vitamin B2)
• -flavoprotein accept H atoms (2 electrons and 2 protons are transferred)

• heme containing proteins (iron-porphyrin ring)
• -different classes of cytochromes with different reduction potentials, but all have an iron section to be reduced and oxidized

• Cytochrome example: heme group in blood
• Porphyrin Degrading Enzymes get blood out of clothes

• -Fe²S² and Fe⁴S⁴
• -have a range of reduction potentials

• -hydrophobic-lipid soluble-diffuse through membrane
• -similar to vitamin K

• -electon transport carriers-oriented in the membrane in such a way that a separation of proton from electrons occurs across the membrane during electron transport
• -protons pumped to the outside
• -electrons move down the electron transport chain until they reduce oxygen
• -oxygen is reduced to water-hydrogen for the water come from inside the cytoplasm

• Electrical and pH gradients
• Protons are pumped out of cell and energy is stored in these gradients

• NAD+ is the best electon donor
• O₂ is the best electron acceptor

• Complex 1
• 1. NADH donates 2H+ and 2e- to FAD
• 2. FADH donates 2e- to iron-sulfur protein
• but the 2H+ are released into the environment
• 3. 2H+ from the cytoplasm and 2e- from Fe-S protein reduce coenzymeQ

• Complex III
• 4. Coenzyme Q passes e- to cytochrome bc1
• 5. Fe-S protein (Rieske protein) passes the electrons to cytochrome c1 and eventually to cytochrome c (periplasmic protein)

• Complex IV
• 6. Cytochrome c diffuses to cytochrome aa3 and donates electrons
• 7. O2 is reduced to water

• ATP Synthase
• Oxidative Phosphorylation

• FO portion crosses membrane
• F1 portion is inside cell and catalyzes ATP synthesis

Protons enter FO, cause conformation change of F1 and create ATP

• block electron flow and thus there is no proton motive force established
• eg. CO, CN- -bind to cytochromes

• prevent ATP synthesis without affecting electron transport
• eg. Dinitrophenol, dicumarol-make membranes leaky destroying the proton motif force

–Efficiency of energy capture= 40%

–Efficiency of an Internal combustion engine= 20%

Found: Wetland soils and water, human digestive tract

• Environmental modulation of ETS
• 1. Food is limiting- less NADH entering the system (alternative NADH dehydrogenase)

2. Low oxygen conditions (different terminal electron acceptor)

• Fe ³⁺
• NO₃-
• NO₂-
• S
• CO₂
• SO₄ ^2-

Still have proton gradient and ATP synthase but energy yield is lower

-compounds that serve as terminal electron acceptors can be a nutrient source (ex. Nitrate, Nitrite are terminal electron acceptors also used for amino acid synthesis)

• -electron acceptors
• -large amounts of compounds reduced
• -reduced electron acceptor is excreted into the environment

• -obligate and facultative anaerobes
• -reduced waste products (nitrite) are excreted in significant amounts

• Redox potential=+ 0.42 v (+ 0.82 v for oxygen).
• -Nitrate reduction is repressed by the presence of oxygen

Nitrate Reduction

• Examples:
• Paracoccus dinitrificans
• Pseudomonas stutzeri
• Rhodobacter sphaeroides

• -sulfate to sulfite to hydrogen sulfide
• -marine environments, hydrothermal vents
• -obligate anaerobes
• **Not many protons are pumped through ATP Synthase

Sulfate Reduction

Hydrogen gas is a strong electron donor, can be used to reduce CO₂ to methane

Carbonate reduction

use of molecular hydrogen as an electron donor

• Carbonate reduction
• most important group of CO2 reducers (Archaea)
• Produce methane as waste product
• Found in landfills and arctic poles, also found in digestive tract of cows

• Methanogens have electron acceptors (coenzymes) that differ from other bacteria and archaea.
• -still have proton motive force but very low energy yield

Homoacetogens- Not seen in eukaryotes. Use methane but produce acetic acid (acetogenesis)

Ferric Ion (Fe3+), Manganese, chlorate, uranium

Fe2+ was likely the dominant electron acceptor in early Earth

Geobacter metallireducens- can reduce metals by grabbing with pilli

Can be used to clean environment

Ex. Fumerate is reduced by succinate

Usually do fermentation when no final electron acceptor is present

• H2, butyrate, formate
• Excreted from cell when produced
• *Glycolysis is not the only way to get fermentation products

Ion pumps can create a gradient (ex. Na+) that stores energy

• •System of 20 individual, miniaturized tests used to determine the metabolic capabilities of the organism.
• Used to determine genus & species