Question

Which of the following reaction categories would be most likely to have the lowest ΔG value?

Select one:

a. Catalyzed Endergonic Reaction

b. Catalyzed Exergonic Reaction

c. Uncatalyzed Endergonic Reaction

d. Uncatalyzed Exergonic Reaction

e. A and B

f. A and C

g. B and D

h. C and D

--

Upon activation of a G protein-coupled receptor, the G protein converts a GDP into a GTP

Select one:

True

False

--

Answer 1

1. Answer- g. B and D

ΔG is the change in free energy and it is calculated by following formula

ΔG = Gfinal - Ginitial

For exergonic reactions reactants have more energy than products hence ΔG has negative value ( ΔG ) while for endergonic reactions initial energy is lower than final reactions (reactants have low energy and products have high energy) therefore ΔG has negative value (  ΔG 0 ).

However catalyst lower activation energy , it do not change free enrgy or ΔG .

2. Answer- True

When ligand bind with G protein coupled receptor , it undergoes conformational change and  activates G protein by exchanging GDP with GTP  by guaninne exchange factor ( GEF) .