Bioenergetics Flashcards
Highly coordinated cellular activity in which many multi-enzyme systems (metabolic pathways) cooperate
Metabolism
Breaking down of biochemical fuels to extract energy (energy yielding processes)
Catabolism
Building up biochemical fuels to sustain life (energy-requiring)
Anabolism
Metabolism in context of thermodynamics
Bioenergetics
Utilization and production of energy
Obey fundamental laws of thermodynamics
Metabolism
Field concerned with the transformation &use of energy by living cells
Determining the direction and extent to which biochemical reactions occur
Bioenergetics
A thermodynamic factor that is a measure of change in heat content of the reactants & products (1st law)
Enthalpy ΔH
Measure of change in randomness or disorder of reactants & products(2nd law)
Entropy ΔS
Energy can neither be created nor destroyed. Can only be transformed from one form to another.
Law of conservation of energy
1st law of thermodynamics
Enthalpy in 1st law of thermodynamics can be:
Exothermic - heat released, -ΔH value
Endothermic - heat absorbed, + ΔH value
Spontaneous if such process will cause an increase in the entropy ΔS of the universe
2nd law of thermodynamics
If entropy ΔS is +, -, and at 0 means
+ => process is spontaneous
- => non spontaneous process
0 => system at equilibrium
Combination of Enthalpy ΔH and entropy ΔS in 1st and 2nd laws of thermodynamics will result to:
Gibb’s free energy by Josiah Willard Gibbs
Gibb’s Free energy equation = energy available to do work ΔG
ΔG = ΔH - T ΔS
T= temp in kelvin, K
A variable criterion of the spontaneity of reactions
Gibb’s free energy
If ΔG is (-) means:
Loss of energy:
Reaction:
Loss of energy: exergonic
Reaction: spontaneous
If ΔG is (+) means:
Gain of energy:
reaction:
Gain of energy: endergonic
Reaction: non spontaneous
If ΔG is 0, reaction is?
Equilibrium
Standard free energy change is obtained at:
25C and 1 atm
Equilibrium constant
Keq=[C]c[D]d / [A]a[B]b
Substances that tend to give up electrons & be oxidized
Reducing agents
Substances that tend to accept electrons & be reduced
Oxidizing agents
Measure of electron-transfer potential
pH is 7.0
More (+), more tendency to gain electrons and be reduced (oxidizing agents)
Tendency of a substance to gain electrons and cause the oxidation of another substance
Standard Reduction Potential, E°
Determine the effect of concentration on cell potential
Nernst equation
Function in a way that metabolism becomes more economically manageable & comprehensive
Co-enzymes as activated carriers
Major electron acceptor in oxidation of fuel molecules
NAD+ / NADH
Used in reductive biosynthesis
NADPH / NADP+
Nicotinamide adenine dinucleotide (phosphate)
An active form of NIACINE (vitamin B3)
Redox co-factors
Both can accept a proton & 2 electrons when a substrate molecule is oxidized
NAD+ / NADH
NADP+ / NADPH
Flavin adenine dinucleotide and Flavin mononucleotide
Active form of RIBOFLAVIN (vitamin B2)
Redox co-factors
Both accept hydride ion (H+ + 2electrons) plus another proton
FAD / FADH2
FMN / FMNH2
Known as Coenzyme Q or CoQ
Mobile electron carrier in the electron transport chain
Ubiquinone
Heme-containing proteins that serves as electron carriers in respiratory and photosynthetic electron transport chains
Cytochromes
Activated carrier of 2 carbon fragments
Co-factor in acetylation
Derived from PANTOTHENATE (vitamin B5)
Coenzyme A (CoA)
The energy currency of the cell
Hydrolytic cleavage of the high energy phosphate bonds is coupled with an energy spontaneous) reaction.
ATP (Adenosine Triphosphate)
Aim is to attain a negative ΔG°’, therefore rendering the reaction spontaneous
The overall ΔG°’ for a chemically coupled series of reactions is equal to to the sum of the ΔG°’ of the individual steps
Biochemical reactions that are thermodynamically unfavorable are coupled with those that are favorable
Coupling reactions
How do cells make ATP
Autotrophic metabolism
Heterotrophic metabolism
Photosynthesis through Photophosphorylation
Autotrophic metabolism
Cellular respiration (aerobic & anaerobic)
> substrate level phosphorylation
> oxidative phosphorylation
Heterotrophic metabolism
