Chapter 13 Flashcards
Catabolism
breakdown of complex molecules into smaller ones
anabolism
reactions that build cells
Catabolism provides energy for
anabolism. some energy is released as heat.
Metabolism
all chemical reactions in an organism
• Balance b/w catabolism and anabolism
Entropy
measure of randomness in a system
Cells use energy to assemble
disordered molecules into ordered ones.
Gibbs free energy change (ΔG)
how much energy is available to do work. Negative ΔG – reaction is favorable
ΔG=ΔH-TΔS
ΔH = change in enthalpy
• Heat absorbed/released as reactants become products
• ΔS = change in entropy
• More ordered = lower entropy
Excess reactants over products
more negative ΔG
environ factors that change ΔS and ΔG
• Temperature, pressure, ionic strength
Standard reaction conditions
• Temperature 298K, Pressure 1 atm, concentration 1M
accounts for concentration
ΔG=
ΔG° +RT lnQ
• Q – reaction quotient
• R – gas constant
• T – temperature in K
A+B ⟷C+D
Q=?
if products=reactants
if products < reactants
Q= C D/A B
If products = reactants, Q = 1; ln(1) = 0; standard conditions
If products < reactants, Q < 1; ln(<1) = negative number
temp can change Q
Cells often break down reactions
into several steps
Cells need energy carriers to transfer energy between reactions
energy carriers are
molecules that gain/release small amounts of energy in reversible reactions
