Bioenergetics and Regulation of Metabolism Flashcards
Biological systems are consider (open/closed) systems?
Open
bc they can exchange both energy and matter with the environment
Internal energy in closed system
The sum of all of the different interactions btw and within atoms in a system
-vibration, rotation, linear motion, and stored chemical energies all contribute
ΔU = Q - W
Bioenergetics
Term used to describe energy states in biological systems
Enthalpy (ΔH)
the overall change in heat of a system during a reaction
At constant pressure and volume, ___ and ___ are equal
ΔH and Q
Entropy (ΔS)
Measures the degree of disorder or energy dispersion in a system
Gibbs free energy equation
ΔG = ΔH - TΔS
Negative ΔG is a ____ rxn
Spontaneous
no net loss of free energy
Positive ΔG is a _____ rxn
Nonspontaneous
net gain in energy
ΔG and ΔG° relation equation
ΔG = ΔG° + RT ln (Q)
modified standard state
[H+] = 10^-7 M
pH = 7
- used for biochemical reactions bc a 1M concentration would give a PH of 0 which is too acidic for the body
-given the symbol ΔG°‘
Fats are more energy dense and therefore usually preferred for
long-term energy storage
ATP structure
ATP
Mid-level energy carrier
-formed from substrate-level phosphorylation and oxidative phosphorylation
-consists of an adenosine molecule attached to 3 phosphate groups
-usually formed from ADP + Pi with an energy input
Why do we want to use a mid level energy carrier (ATP) instead of a high level?
Think about wallet
-if you could never get change back, what dollar would you want most of?
-single dollar bills
-same with this: ATP cannot get back the “leftover” free energy after a reaction so it’s best to use a carrier with smaller free energy
ATP is consumed from either
Hydrolysis or the transfer of a phosphate group to another molecule
adenosine monophosphate (AMP)
a low-energy compound that results from the removal of two phosphate groups from ATP
ATP hydrolysis is most likely to be encountered in the context of
Coupled reactions
ex: movement of sodium and potassium against their electrochemical gradients is harnessed from hydrolysis of ATP
ATP cleavage
the transfer of a high-energy phosphate group from ATP to another molecule
-usually activates or inactivated the target molecule
-bc of the phosphoryl group transfers, the overall free energy of the reaction will be determined by taking the sum of the free energies of the individual reactions
phosphoryl group transfers
- the overall energy of the rxn is determined by taking the sum of the free energies of the overall rxns
- ATP can provide a phosphate group as a reactant
- ex: in the phosphorylation of glucose in the early stages of glycolysis, ATP donates a phosphate group to form G6P
ATP is used to fuel ________ reactions or to _______
Energetically unfavorable reactions
activate or inactive other molecules
Spontaneous reactions have a _____ electromotive force (E)
Positive
high energy electron carriers
NADH, NADPH, FADH2, ubiquinone, cytochromes, glutathione
Membrane bound electron carriers
-embedded within the inner mitochondrial membrane
-ex: FMN, which is bonded to complex I of the ETC and can also act as a soluble electron carrier
Flavoproteins
-contain a modified vitamin B2 (riboflavin).
-nucleic acid derivatives (FAD or FMN)
-electron carriers notably in mitochondria and chloroplasts
-coenzymes for the oxidation of fatty acids, decarboxylation of pyruvate, and reduction of glutathione
Postprandial state
-aka absorptive or well-fed state
-Occurs shortly after eating; generally lasts 3-5 hrs
-Nutrients move from the gut to hepatic portal vein to the liver, where they are stored or distributed to other tissues
-Increases insulin levels
-more anabolism than catabolism
Anabolism
Synthesis of biomolecules
Catabolism
Breakdown of biomolecules for energy