Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
25 Cards in this Set
- Front
- Back
|
Conservation of energy (1st law)
|
Can change form
Chemical (food) Kinetic (motion) Heat Light (photosynthesis, fireflies) |
|
|
H, delta H
|
The amount of energy is represent by the term enthalpy (H) and usually by change in enthalpy (DH)
|
|
|
-H
|
A change that leads to a negative enthalpy is a favored reaction
spontaneous |
|
|
2nd law of thermodynamics
|
Disorder in the universe can only increase
low entropy = high order high entropy = low order Disorder or randomness is represented by the term entropy (S) and usually by the change in entropy (DS) Energy and entropy are not directly linked It takes energy to melt ice (increased disorder) It takes energy to created a cell (increased order) |
|
|
Gibbs Free Energy
|
The combined effects of enthalpy and entropy
The change in Gibbs free energy is given by: DG = DH – TDS Favored (spontaneous) reactions require a negative DG, which can be achieved by a negative DH or a positive DS, or both |
|
|
Entropy applies to biological
molecules and cells... |
A properly folded protein is in a highly ordered, low entropy state
An unfolded protein is in a disordered, high entropy state Biological order is made possible by the release of heat energy from cells |
|
|
Energetically unfavorable reactions...
|
can be driven by energetically favorable reactions because the net free-energy change for the paired couple is less than zero
|
|
|
To overcome the activation energy barrier...
|
most reactions require energy input from catalysts
|
|
|
The Free-Energy Change for a
Reaction Determines Whether It Can Occur... |
the free energy of Y is greater than the free energy of X, deltaG < 0, reaction is spontaneous
energetically unfavorable reaction, deltaG > 0, reaction only occurs if coupled w/ an energetically favorable reaction |
|
|
The Free-Energy change for a
reaction... |
Determines whether it can occur
|
|
|
Ex. of coupled reactions
a to b = DG >0 b to c = DG <0 |
If the sum of the two DGs is <0 the reaction from A to C is a favored reaction.
|
|
|
Dissociation
|
AB -> A + B
dissociation rate = dissociation rate constant * concentration of AB dissociation rate = koff * [A] * [B] |
|
|
Association
|
A + B -> AB
association rate = association rate constant * concentration of A * concentration of B association rate = kon * [A] * [B] |
|
|
At equilibrium for Association and Dissociation.....
|
association rate = dissociation rate
kon [A][B] = koff [A][B] [AB]/[A][B]= kon/koff = K = equilibrium constant |
|
|
The Concentration of Reactants.....
|
Influences the Free-Energy Change
and a Reaction’s Direction |
|
|
The Standard Free-Energy Change
Makes it Possible..... |
to Compare the Energetics of Different Reactions
DG = DGo + RTln[X]/[Y] |
|
|
Enzymes do not change...
|
the equilibrium just the rate of the reaction
|
|
|
Cells are in a chemical disequilbrium....
|
because eventually the reaction will stop occurring and the cell will die because its needs fluctuate like the reaction
|
|
|
Rapid Diffusion Allows....
|
Enzymes to Find Their Substrates
Vmax and KM Measure Enzyme Performance the greater the rate of the rate the higher the substrate concentration |
|
|
Reduced
|
gains electrons
|
|
|
Oxidized
|
Loses electrons
|
|
|
NADH, NADPH, FDH2
|
electrns and hydrogen donators
|
|
|
NADP is...
|
an electron carrier
|
|
|
Electrons can be carried by...
|
a variety of molecules
ATP = phosphate |
|
|
Biosynthesis
|
atp can be used to join molecules
|
