Bioenergetics

Question 1

what are chemical reactions favored by?

Answer 1

-lowest energy state (stablest chemical bonds) (enthalpy)
-maximum randomness (entropy)

net effect of both drives reactions

Question 2

enthalpy

Answer 2

ΔH=heat change at a constant pressure
-quantitates tendency to form bonds

Question 3

exothermic

Answer 3

releases heat
negative ΔH

Question 4

endothermic

Answer 4

absorbs heat
positive ΔH

Question 5

entropy

Answer 5

ΔS=degree of randomness
-change in randomness
-increase in randomness=positive ΔS=more disordered, more favored

Question 6

free energy and spontaneity of chemical reactions

Answer 6

Gibbs Free Energy
-ΔG=ΔH-TΔS
-doesn’t affect rate (kinetics)

Question 7

ΔG<0

Answer 7

forward reaction favored
exergonic

Question 8

ΔG>0

Answer 8

reverse reaction favored
endergonic

Question 9

ΔG=0

Answer 9

reaction at equilibrium

Question 10

coupling reactions

Answer 10

chemical coupling of exergonic and endergonic reactions allows otherwise unfavorable reactions
-ATP reacts directly with the metabolite that needs activation

Question 11

why is high energy of hydrolysis of phosphoanhydride bonds?

Answer 11

-electrostatic repulsion btwn O-
-resonance stabilization of products
-ionization stabilization
-greater solvation of products