Energy and Enzymes Flashcards
(17 cards)
What is the function of cells
To break down and rebuild macromolecules
What is Metabolism
the chemical reactions inside cells
Catabolic pathway
Breaks bonds, releasing energy
- Using Kinetic energy (motion)
Anabolic
Bonds formed, stores potential energy
Thermodynamics 1st Law
“Energy can neither be created nor destroyed (conservation of energy)”
- But energy can change forms, transfer, flow
- Consequence of the 1st law: the total energy of a ‘closed’ system does not change
Thermodynamics 2nd Law (Entropy Rules)
- Energy transfer is not 100% efficient
- Entropy: (Disorder) Cannot be transformed into useful energy
-> Heat flows from high temp to low temp
-> Gas = most disordered state of water
-> Biological systems do Heat transfer = increase Entropy = Thermal Equilibrium
Free energy
Usable energy released from a chemical reaction avaible after accounting for entropy
Enthalpy
- Total heat content of a system
- The total energy of a system
Endergonic reactions
- When change in free energy > 0
- Products have more stored/potential energy than reactants
- Forming bonds that will store energy
- Non-spontaneous
Exergonic reactions
- When change in free energy < 0
- Reactants have more stored/potential energy than products
- Break bonds, releases energy
-> The kinetic energy performs work due to increased Entropy - Spontaneous
Activation Energy (EA)
- Energy input for endergonic/exergonic reactions
- Higher EA = slower reaction
- Endergonic = slowest reaction, requires most EA bc of energy barrier need to break bonds in reactants before forming new bonds
- EA comes from heat that produces high energy collisions
What does EA do for exergonic reactions
- When bonds break: Unstable High Energy Transition State - but EA overcomes this energy barrier
ATP
- Energy currency
- Adenine, a sugar, 3 phosphate groups forms the nulceic acid “ATP”
How does the free energy released in ATP hydrolysis work inside a cell?
It is immediately transferred to another molecule via an enzyme
Enzymes
- Use ATP to regulate and speed up reactions in cells
- Reduce EA bc they stabilize transition state
-> Do this by energy coupling, by first energying themselves - Enzymes don’t change free or potential energy of reactants or products
- They don’t create reactions
Step 1: Energy coupling- enzyme activation
- Enzyme has to change shape and become a higher energy state
- Uses energy stored in the gamma phosphate bond: By breaking the bond and adding the phosphate to itself:
- You now have a higher energy enzyme that can catalyze a reaction
Step 2: Catalysis
- Enzyme will bind two substrates and bring them into proximity
- Then uses the phosphate to build that bond (in the proximity)
