Exam 2: Energy and Enzymes Flashcards
In what 2 circumstances do reactions take place?
- Reactants collide in precise orientation
- Reactants have enough kinetic energy to overcome repulsion b/t the electrons that come in contact during bond formation (activation energy)
What is energy?
The ability to promote change or do work
2 forms of energy
kinetic and potential
Kinetic energy is associated with…
Movement
Potential energy is associated with…
Structure/location
Chemical energy
energy in molecular bonds, form of potential energy
=> structure of a molecule determines potential energy
First Law of Thermodynamics
Energy cannot be created or destroyed, but can be transformed
Second Law of Thermodynamics
Transfer of energy from one form to another INCREASES THE ENTROPY of a system => as entropy increases, there is less energy available for organisms to use
Where do electrons have high potential energy
In outer electron shells
Formula for free energy change
ΔG=ΔH-TΔS
ΔG
Change in free energy
ΔH
Change in total energy (enthalpy)
T
Temperature in Kelvin
ΔS
Change in entropy
ΔG > 0
endergonic
ΔG < 0
exergonic
Which type of reaction occurs spontaneously?
exergonic
Which type of reaction is thermodynamically favored?
Exergonic
How can you conduct an endergonic reaction?
Couple it with an exergonic reaction
What are 2 ways in which energetic coupling occurs?
- Transfer of high energy electrons
- Transfer of a phosphate group
What are 3 examples of coupled reactions?
- Redox reactions: electron transfer
- Electron carriers: NADH and FADH2 both receive high energy electrons to deliver to the right places
- ATP driven reactions: include high energy electrons
What are redox reactions?
Reactions that involve transfer of electrons
The more CH bonds…
The more reduced it is
The less CH bonds…
The more oxidized it is
Reduced molecules have higher or lower potential energy?
Higher, gains a proton