Ch 9: Energy, Enzymes, and Metabolism

Question 1

Gibbs free energy

Answer 1

∆G=∆H-T∆S

Question 2

Enthalpy

Answer 2

∆H; heat energy and bonding changes (covalent and noncovalent)

neg values of ∆H= heat is given off; favorable

Question 3

Entropy

Answer 3

∆S; disorder

positive∆S: disorder is greater; favorable

Question 4

catalyst

Answer 4

aka enzyme

increase rate of reaction

do NOT affect equilbrium of reaction

ARE NOT altered by reactions

Question 5

activation energy

Answer 5

energy needed to start a reaction aka Delta G double dagger

• Enzymes decrease the value of “Delta G double dagger aka activation energy w/out affecting either the energy of reactants or products

Question 6

how do enzymes speed up reactions

Answer 6

1) overcome unfavorable entropy of transition states
2) enzymes use their ability to bind substrates in very precise orientations to overcome the entropy barrier needed to get to a transition state

more time to react (1s instead of 10E-10 s) which will increase the rate of reaction

Question 7

what other mechanisms do enzymes have to increase reaction rate?

Answer 7

acid-base catalysts

strain substrates

Question 8

enzyme kinectics

Answer 8

substrate concentration is much greater than the enzyme concentration

E=S–>E+P

if substrate increases–>more product