Bioenergetics Learning Objectives

Question 1

Define entropy

Answer 1

ΔS is the change in entropy (randomness) of a rxn

Question 2

Define enthalpy

Answer 2

ΔH is change of enthalpy (bond energy) of a reaction. Exothermic rxns -ΔH. Endothermic rxns +ΔH

Question 3

Define Free energy

Answer 3

ΔG is the free energy. -ΔG means spontaneus. ΔG is the maximum amount of work that a process can generate at a constant temp and pressure

Question 4

Define High Energy compounds

Answer 4

The less oxidized the carbon, the more unstable. Lipids are less oxidized and hold the most energy.

Question 5

Define Oxidation-reduction Reactions

Answer 5

Oil Rig. Oxidation is Loss and Reduction is Gain of electrons. ΔE=Eacceptor- Edonor

Question 6

Discuss the first law of thermodynamics

Answer 6

Energy is neither created nor destroyed. Only converted into different forms

Question 7

discuss second law of thermodynamics

Answer 7

entropy of the universe is always increasing

Question 8

Standard Conditions

Answer 8

289K (25C), 1atm, pH7, 1M of reactants and products.

Question 9

Equations of free energy. name 5

Answer 9

Δ G=-nFΔ E
ΔG'= -RTlnKeq
ΔG=ΔG'+RTln(p/r)
ΔG=ΔH-TΔS
ΔG=ΔG'+2.3RTlogQ

Question 10

Electron transfer in biological systems can generate nergy

Answer 10

Glucose is a major source of electrons and O2 is the final acceptor.
Biological “circuit” contains: cytochromes, Fe/Fe2+, heme groups, which oxidized and reduced.
The electromotive force is used to make ATP, NADH, NADHP.
Free energy is made when e- flow from low to high electronegative (E) compounds.
ATP is made by- harnessing the energy in H+ gradients formed across the inner-mitochondrial membrane, which runs the ATPsynthase which uses rotational catalysis to form phosphate bonds.

Question 11

standard free energy changes for a reaction are additive, - and + free energy rxns can be coupled

Answer 11

Couple the hyrdolysis of ATP with a +ΔG rxn can make it happen.

Question 12

Describe major high energy compounds used in biological systems and the principle energy storage in high energy bond.

Answer 12

2 High energy bonds

1. Thioester C-S (acetyl CoA)
2. high energy phosphate bonds.
   a. phsophoanyhydride P-O-P (atp)
   b. phosphocreatine P-N
   c. Phosphenolpyrucate C-O-P

Hydrolysis of phosphoanyhydride bonds in atp releases energy.

Question 13

Equilibrium constant

Answer 13

Keq= Kf/Kr=[C}[D]/[A][B]
at equilibrium Keq=ΔG=0
the concentration of products and reactants in a cell determines value of ΔG and how much energy is released or used.