Lecture 6 Flashcards
definition of metabolism
sum of all reactions in a living organism aimed at maintenance, development and reproduction
difference between cost of errors in lab and industry
Way bigger cost in industry because production at a way bigger scale
metabolism : what comes in and what comes out
nutrients -> biomass, byproducts, heat
2 types of processes in metabolism : which one requires energy ?
Catabolism : spontaneous, yields energy
Anabolism : new biomass, requires energy
adding biomass : chemical reaction, how can we estimate oxygen ?
glucose + O2 + NH4+ -> CH1.8O0.5N0.2 + CO2 + h2O + H+
using the perfect gas law
gibbs free energy : used for what, what is it
Energy available for cell to use : estimate if a reaction is thermodynamically spontaneous or if energy is required
In non-equilibrium systems, what does deltaG depend on ?
On the concentrations !!
different ways to measure metabolism rate
Catabolic focus :
- electron acceptor consumption rate (mainly O2)
- byproduct production rate (mainly CO2)
- enzyme activity
- heat
Anabolic focus :
- incorporation assays
where and what is the electron transport chain (ETC)
In mitochondria !!
Electrons are transferred from NADH (or FADH2) through protein complexes to the electron acceptor (oxygen).
The electron transport creates a proton gradient (more in intermembrane space) -> drives synthesis of ATP
what about microbial ETC ? where ? what else is it used for ?
They don’t have mitochondria -> in membrane.
Proton motive force also used for active transport and rotation of flagella.
redox assay : principle
we measure the consumption rate of electron acceptors.
Ex : formation rate of formazan from tetrazolium salt is proportional to catabolism.
Name different electron acceptors
oxygen, S, SO4, NO3, organic compounds, metals (Fe, Mn)
ATP : what is accounted for, concentration ?, AEC
Account for ATP, ADP and AMP.
Humans : 1-5 mM.
Spores : very low because almost no metabolism needed.
AEC = adenylate energy charge (0.8 in active cell) -> more relevant than absolute concentration of ATP alone.
(ATP + 0.5ADP) / (ATP + ADP + AMP)
carbon source : metabolism rate ?, dependance to T, 2 examples
Rate of consumption (and increase of biomass) is proportional to metabolic rate.
When T increases, it becomes faster.
Glucose, Lactose, …
examples of byproducts
CO2, NO2, H2S, biomass
incorporation assays : 3 examples
1) radioisotope incorporation (radiolabeled compounds in DNA or proteins)
2) stable isotope probing : use of stable isotope labeled substrates to probe the microbial utilization of these substrates to build their macromolecules.
3) substrate analog probing : synthetic compounds analogous (sometimes with fluorescent tags) to natural molecules incorporated into macromolecules
link between metabolism and heat (formula)
deltaG = deltaH - t*deltaS
is entropy needed in aerobic respiration ?
No it can be neglected
calorimetry : what it measures
Real-time monitoring : measures net rate of heat flow over time -> calculate heat produced or consumed
how many peaks for e.coli in calorimeter with different substrates
3 :
- glucose respiration
- glucose fermentation
- lactose fermentation
2 calorespirometric ratios
1) oxycaloric Q/O2 : fixed at 455+-15 kJ/mole -> deviation means another process is ongoing (except if deltaH = 0)
2) Q/CO2 : variable for sugars, proteins or lipids -> gives indication on carbon source and growth efficiency
