Chapter 5 Microbial Metabolism Flashcards
Work is
making a change in matter
Energy
- Chemical work- making/breaking bonds
- Transport work- moving across membrane or around cell
- Mechanical work- turning of flagella
Thermodynamics
Study of energy conversions
Laws of Thermodynamics
1st-energy can neither be created nor destroyed
- can change form
2nd- entropy- measure of random disorder
- spontaneous reactions favored
- move indirection that increases entropy
2 Fundamental tasks required for growth and reproduction
- Catabolism-decomposition reactions-break into simpler
- favored by entropy
- Anabolism- building reactions - simple/small into larger, more complex
Metabolism
sum of all chemical reactions in an organism
- Amazing diversity but also unity
- Ordered, enzyme-mediated pathways
- ATP- energy coupling molecule
- provides power to anobolic from catobolic - Redox- reduction and oxidation- moving electrons
- Highly variable
AB—> A + B reaction
deconstruction/catabolic reactions
Catabolic reactions
- hydrolytic(h2o in), exergonic(-deltaG)
-K(equilibrium constant) eq>1, spontaneous
-Cellular Respiration- provides precursor molecules and energy for anabolic
rxns
- provides precursor molecules and energy for anabolic
- (-)deltaG=change in Gibb’s Free Energy(lost)
-K= >1 = more product
-K = 1 = eq. amounts of product and reactants
-reactants have higher energy than products
Anabolic reactions
- Condensation rxns-take h2o out
- create bonds
- dehydration synthesis, endergonic(+deltaG)
- K eq. AB
Precursor Metabolites
Amphibiolic rxns
- linkage between catabolic and anabolic rxns
Activation Energy/Energy of Activation
-amount of energy initially needed to put in to cause rxn
3 things must have for chemical reactions
- enzymes
- h2o solution
- energy
catalysts
- influence reaction time- speed up rxn
- temperature
- substrate concentration
- enzymes- biological catalysts- most commonly used
A catalyst lowers____
activation energy
Enzymes
- all protein or holoenzymes( protein and accessory)
- Apoenzyme + Cofactor(coenzyme)
Characteristics of enzymes
- do not make reactions happen that could not happen on their own
- not permanently altered or used up- recyclable
- substrate specific(active site) - chemically reactive
- function is based on structure
- is not part of product
Enzymes are categorized based on ____
what chemical reaction they are a part of
-ends in “ase”
Unconventional Enzymes
- not made of proteins
- Robozymes- novel type of RNA-cuts other RNA
- Extremozymes- have molecular applications
- in extreme organisms
- adapted to extreme environments
Mechanism of Enzymatic Action
Induced fit model
-enzyme “fits” itself around substrate
Factors influencing enzyme activity
- denaturing(unfold,loss of structure,nutralize) stresses
- heat, pH, UV radiation, chemicals
- substrate concentration
- competitive inhibition
- non-competitive(allosteric) inhibition
Competitive inhibitor
-competes with substrate for active site on enzyme
Allosteric site
site on enzyme that is not the active site
Non-competitive inhibitor
binds to allosteric site causing the substrate of the enzyme to change and not allow for binding at the active site
Feedback ihibition
Negative allosteric effection
- regulates metabolic pathway by stopping first path
- Isozyme
Reduction- Oxidation Reactions
- Reduction- electron acceptor- recieves energy
- Oxidatation- electron donor-loses energy
- redox rxns liberate energy
- always coupled
Standard reduction potential(E’O)
measures likely-hood of redox couple to give up electrons
Reducing Power
- potential energy
- carrying electrons
Common electron carrier
NAD and FAD
Electrons moving toward less negative ____ release _____
acceptors
free energy
Amount of energy released correlates with _____ of difference in ___
magnitude
E’o- oxygen
ATP Synthesis
Free energy used to phosphorylate ADP forms of ATP
- metabolic money!
Lower E’o value means ___ energy
more
Substrate level phosphorylation
- chemical energy- move from 1 to the other
- oxidative phosphorylation- break down of
- energy from proton motive force
- photophosphorylation- radiant energy-sun
- high phosphate group transfers potential
Heterotrophic Metabolism
- oxidize energy(electron) rich organic molecules
- typically utilize carbohydrates
- Glucose(C6H12O6) is #1 source
- organic—>ATP(main)
- increases metabolic efficiency
Three possible pathways based on final electron receptor
In order of efficiency
- aerobic respiration- exogenous(oxygen)-most efficient b/c of O2
- anaerobic respiration- exogenous- NO O2
- Fermentation- endogenous organic-NO O2
- 1st step; not complete;least energy yield
- Fermentation- endogenous organic-NO O2
- exogenous- final electron acceptor material
Fermentation
-glycolosis
Anaerobic/aerobic pathways
- glycolosis
- Kreb Cycle
- electron transport
- only difference is final transfer electron
- anaerobic yields less energy
Pathways are Amphibolic and
provide
- energy
- reducing power
- precursor metabolites
Respiration uses ____ power to generate ___
reducing
ATP
NADH and FADH2 provide ____ to power ____ motive force
electrons
proton
- reducing power
Terminal electron acceptor varies
- oxygen- aerobic respiration
- Anaerobic respiration- alternate inorganic molecules
The first step in respiration is _____, from this 2 molecules of _____, ______, and _____ are produced _____ in the _____ of prokaryotes and eukaryotes. The phosphorous is added through ________. This pathway is name ______.
- glycolysis
- ATP, NADH, pyruvic acid
- anaerobically
- cytoplasm
- substrate level phosphorylation
- Embden-Meyerhof Pathway
Pentose phosphate pathway
- produces many intermediate materials for other pathways
- can biosynthesize 6 carbon sugars
- major contributor to biosynthesis
- reducing power in NADPH
- vital precursor metabolites for anabolic pathways
- intermediates may be used to generate ATP
True alternative to glycolysis
Entner-Doudoroff pathway
- typically not seen in gram + bacteria
- major contributor to biosynthesis
- reducing power - NADH & NADPH
- vital precursor metabolites for anabolic pathways
The Kreb Cycles’ actual name(TCA)
Tricarboxcylic acid cycle
The Kreb cycle takes place in the ____ of prokaryotes and in the _____ of eukaryotes. This is an____ respiration. _____ gives up its carbon as ___. ___ total. _______ is regenerated with every turn. This also acts as a pick up molecule for ___. ____ ATP are produced by _______.
cell membrane mitochondria membrane anaerobic Pyruvic acid CO2 6C Oxaloacetate ATP 2 substrate-level phosphoylation
TCA cycle occurs ___ per glucose
twice
Net yield of product per glucose molecule
- 6 CO2
- 2 ATP
- 8 NADH = 3 ATP
- 2 FADH =2 ATP
Electron Transport Chain can work _____ or _____ .Electrons move down chain and set up ___ gradient that drives _____.
aerobically
anaerobically
H+
chemiosmosis
If oxygen is not used, anaerobic, less ____ overall is produced.
ATP
Oxidative phosphorylation is
a series of redox reactions creating a step-wise release of energy
Using the Proton Motive Force(PMF) ___synthesis is catalyzed by _____ through a process called _______.
ATP
ATP synthase(ATPase)
chemiosmosis
The H+ use ____ movement to come back across the gradient.
passive
Proton flow across gradient is _____. This is a _____ of energy.
exerogonic
release
By-products of aerobic respiration are ___ and ___
H2O
CO2
The Proton Motive Force is generated by ______ and ____ gradient.
chemical
electrical
Substrate-level phosphorylation net gain of ATP
2 ATP - glycolysis
2ATP - TCA cycle
4 total
Oxidative Phosphorylation net gain of ATP
6 ATP - NADH Glycolysis
28 ATP - NADH/FADH2 TCA cycle
34 total
Anaerobic Respiration is different from aerobic respiration in the final electron acceptor will never be___
oxygen
Nitrate reduction reduces to
nitrite
Denitrification is
the stripping of nitrogen from ecosystem
and produces an unusable source of nitrogen
E. coli uses
nitrate reduction
Pseudomonas used
denitrification
Desulfovibrio uses
reduces sulfate
Archaea use methanogens to reduce____
carbonate
Electron acceptors other than oxygen are ____ efficient. They have less positive ____ _____ then oxygen and have a _____ yield.
less
reduction potentials
lower
Fermentation is also known as____. It is done by organisms that can’t _____. This is an _____ method that occurs in the ____.
glycolysis
respire
anaerobic
cytoplasm
Fermentation produces a net of __ ATP
2
Partial oxidation of substrate in fermentation
NADH is oxidized back to NAD and an organic compund is used as an electron acceptor. usually pyruvate or derivative
Has no oxidative phosphorylation so ATP yield is low
When O2 runs out a switch to ____ takes place. This produces ____ acid by ____ being reduced to lactate.___ accepts electron and protons from ___
fermentation
pyruvate
pyruvate
NADH
Alcohol fermentation process
pyruvate decarboxylated to form acetaldehyde
NADH transfers electrons and protons to acetylaldehyde reducing it to ethanol
Carbohydrates are the main source of energy in ___ of other organic compounds
catabolism - glucose
Microbes may also utilize ____ and ___ for energy but must be broken down into their individual _____.
lipids
proteins
components
Lipases break bonds between_____ and _____. and then feed into different places.
fatty acids
glycerol
In lipid catabolism fatty acid is converted into _____ that enters the ___ cycle.______is converted into DHAP and enters _____.
acetyl CoA
TCA
Glycerol
glycolysis
Protein Catabolism uses ____ and ___. These are used to break into pieces and made to fit in pathway.
proteases
amino acids
