5-1: Energetics and Redox Reactions Flashcards
What is microbial metabolism essential for
Circulation of organic elements (carbon, nitrogen, etc) through environment
What are the four metabolic requirements for all life
- Liquid water
- A source of energy to do work
- Nutrients (e.g. sources of C, N, etc)
- A source of electrons for biochemical reactions
First law of thermodynamics
Energy is neither created nor destroyed
Where is energy conserved/stored
High energy molecules (like ATP)
Energy either comes from __________ or __________
chemicals, the sun
Chemotrophs are…
Microbes that break down high energy molecules to lower energy molecules, use the excess energy to power cell functions
Microbes that capture energy from sunlight are…
phototrophs
Name for chemotrophs that use organic chemicals vs inorganic chemicals
Organic = chemoorganotrophs
Inorganic = chemolithotrophs
Autotrophs vs heterotrophs
Autotrophs use CO2 (inorganic C) to build materials = primary producers
Heterotrophs obtain C from organic compounds (chemoorganotrophs)
Hydrolysis of ATP to ADP used to…
power synthesis of cell components (proteins, membranes, CW) and power cell functions (transport)
What do ATPase enzymes do
Couple energy from ATP hydrolysis to perform other cell reactions
Catabolism vs anabolism
Catabolism = reactions used to obtain E and break down complex molecules
Anabolism = reactions used to synthesized cellular material (use E)
What is metabolism
Series of biochemical reactions needed to sustain life
What is Gibbs free energy
deltaG
Measurement of free E change of a reaction in kJ
What is a negative gibbs free energy
Reactants have more energy than products, the reaction is exergonic (E released) and spontaneous
What is positive gibbs free energy
Reactants have less energy than products, the reaction is endergonic (requires energy) and not spontaneous
Gibbs free E equation
deltaG = deltaG0 + RTlnK
what affects delta G
temperature, [substrates], [products]
What does a high K value do
Increases deltaG (high [products]), reaction less favourable in that direction
Equation for K
K = [products] / [substrates]
How much energy does ATP production require
At least 31.8 kJ /mole
How much energy does aerobic respiration of glucose release
2895 kJ
What does the cell need nutrients for
Make up core molecules in the cell (DNA, proteins, lipids)
serve essential cell functions (Fe, Mg)
What are redox reactions
Reduction/oxidation rxn
Electrons transferred from high E state to lower E state
Redox rxns are the source of energy for…
Chemotrophs
Electrons are at a lower E state when they are associated with…
More electronegative atoms
When glucose loses electrons, it is _______
When O2 gains electrons, it is _________
Oxidized
Reduced
How do redox rxns produce energy
E released when electrons move to lower energy state
How do you write out a redox pair
(oxidized form/reduced form)
e.g. CO2/glucose
what is reduction potential
E0’
The likelihood of a redox couple to act as an electron donor or acceptor
Redox couples with more negative values will usually act as….
electron donors to be oxidized
Redox couples with more positive values have strong tendency to act as….
electron acceptors, to be reduced
What makes CO2/glucose a strong electron donor, with a negative reduction potential
C-H bonds in glucose = electrons in high energy state
Electrons close to oxygen in CO2 = lower energy state
Why is O2/H2O a strong electron acceptor
Hydrogen wants to donate e
Oxygen highly electronegative
In H2O oxygen can steal electrons from H
Electrons associated with O2 = low energy state
A redox pair lower on the redox tower/table will be a…
electron acceptor
A redox pair higher on the redox tower will be a…
electron donor
The larger the difference in redox potential of couples, the larger the…
amount of energy produced larger
Increase in electronegativity =
decrease energy state of e
Where do electrons end up after being transferred from initial e donor
Ultimate acceptor over many biochemical reactions
What is used to shuttle electrons around cell
Soluble electron carriers (nicotinamide adenine dinucleotide (NAD+/NADH))
NAD+ is the ___________ agent, whereas NADH is the ___________ agent
Oxidizing
Reducing (gets oxidized to NAD+)
Enzymatic cofactors are…
non-protein chemical compound or metallic ion that is required for an enzyme’s role as a catalyst
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