Lectures 3 &4: Bioenergetics and Metabolism Flashcards
Heterotropic regulation
s
Homotrophic regulation
w
Autotroph
e
Heterotroph
e
Gibbs free energy
The capacity to do work at a constant temperature and pressure
enthalpy, delta H
heat
Entropy, delta s
- The amount of disorder in a system
- While entropy of a SYSTEM can decrease in a given reaction, entropy of the UNIVERSE always either increases or remains constant
- Can be increased by simply increasing number of molecules or increasing number of molecules in a more “entropic” state, which decreases order and “information (ex: 7 solid molecules to 7 gaseous molecules, or 26 letters of the alphabet all lined up in alphabetical order vs in a mishmash)
∆G°’
-Free energy of a reaction under standard biological conditions, meaning
- 1 atm
- 25 degrees celsius
- pH of 7
- 1 molar concentration of everything EXCEPT hydrogen ions, b/c that would be too low of a pH for biological function
=-RTlnKeq
- Equation above tells you how far to the left or the right a reaction will go under standard conditions
∆G°
-Free energy under standard conditions
Keq
Equilibrium Constant
If Keq is less than one, the reaction is not spontaneous b/c we have more reactants than products at equilibrium
If Keq is greater than one, the reaction is spontaneous b/c we have more products than reactants at equilibrium (for our purposes)
- Can be predicted by ∆G°’ (even though technically i think ∆G°’ calculated by Keq); VERY SMALL CHANGES IN ∆G°’ GIVE LARGE CHANGES IN Keq
spontaneous
-Occurs forward on its own without being driven by some outside force; does NOT mean it occurs quickly, however
ATP
- Adenosine triphosphate
- It contains a lot of energy b/c it has three highly negative phosphate groups next to each other, and removing one releases a lot of energy, and also because when a free phosphate group is in aqueous solution, it has more resonance forms available to it then when in ATP
- Even though the reaction from ATP–> ADP has a very negative ΔG, it has a very high activation energy, which is why ATP doesn’t just convert to ADP quickly. It DOES convert spontaneously (because of the negative delta G), just kinetically very slowly
- ATP hydrolysis happens in the cytosol
AMP
-Adenosine monophosphate
leaving group
d
committed step
- A step that has a very large, negative ΔG, so it is difficult to go backwards b/c the activation energy is SO LARGE now
- Once the reaction has gone past this step, there’s essentially no going back
- There can be multiple committed steps in a pathway
- Committed steps are typically the steps that are regulated by enzymes and whatnot in a pathway