Energy
What is energy?
The ability to do work
_____ is a reaction that results in a release/increase of entropy
_____ is a reaction that results in the absorption/decrease of entropy
Exergonic/exothermic
Endergonic/endothermic
Write out the chemical equation for the hydrolysis of ATP
ATP + H2O -> ADP + Pi + energy
What are enzymes?
Proteins that act as catalysts to speed up reaction rates
What is the activation energy?
Energy required to overcome the transition state
What is the difference between potential energy (PE) and kinetic energy (KE).
Potential energy - associated with the position/configuration of something
Kinetic energy - associated with the movement of something
Between the exergonic and endergonic reactions, which occurs non-spontaneously? What does this mean?
Endergonic
Energy is required, otherwise it cannot occur on its own
What is ATP, ADP, and Pi?
ATP = adenosine triphosphate
ADP = adenosine diphosphate
Pi = inorganic phosphate = PO4^-4
What are the characteristics of enzymes?
Suffix "-ase"
Required for life
Have an active site where the chemical reaction will occur
Specific to the substrate, how its bound, and thus to the reaction
Is not part of the product and can be reused
Does not affect ΔG, but does effect the activation energy
Bonus question: How do enzymes effect the substrates in order to turn them into product?
What is the transition state?
The moment that the reaction starts turning the reactants into products
Provide an example of potential energy and an example of kinetic energy
Act
Draw
Explain
Etc.
Bonus question: what is chemical potential energy?
What is a chemical reaction?
What is ATP and its characteristics?
ATP = energy currency of the cell which fuels most endergonic reactions
High potential energy
Unstable -> short lived and made to be used, not stored
Bonus question: what makes ATP so high in potential energy?
What is induced fit?
Induced fit - the conformation (shape) change of an enzyme when substrates (reactants) bind to the active site once they are properly oriented into the space
Describe the factors influencing enzymes.
Hint: most enzymes are proteins
Temperature affects the mobility of the enzyme and the substrates; it also can denature the enzyme if the temperature is too high
pH affects the enzyme shape and reactivity; it can also denature the enzyme if the pH is too low (acidic)
Bonus question: do these factors vary depending on organism/organelle/organ? Explain
What is entropy?
The amount of disorder/randomness/mess in a system
Dehydration reactions are mostly analogous to _____ reactions while hydrolysis reactions are mostly analogous to ______ reactions
Endergonic
Exergonic
What is energetic coupling? Why does it occur?
Energetic coupling = energy from an exergonic reaction is used in an endergonic reaction
This is because endergonic reactions often need an energy source, exergonic reactions provide this
What is a metabolic pathway?
Draw it out and label (initial substrate, intermediate substrate, final product, reaction 1-n, and enzyme 1-n)
Multi-step process of different chemical reactions all catalyzed different enzymes to produce a product that will act as the substrate in the following reaction until the final product is made
Describe feedback inhibition using the metabolic pathway. Feel free to draw this out.
When there is an excess of the final product, this molecule will go back into the pathway and bind to a specific enzyme, this inhibits the binding of the substrate -> preventing the continuation of the process
What is the first and second laws of thermodynamics?
First - energy cannot be created nor destroyed, merely transformed or transferred
Second - total entropy of a system increases
Draw out exergonic vs endothermic reactions in terms of free energy vs reactant to product
Hint: free energy is on the Y axis and reactant to product (in terms of time) is on the X axis
Free energy is higher in reactants for exergonic reactions
Free energy is lower in reactants for endergonic reactions
Bonus question: what is ΔG?
Explain this process:
[A+B -> C] + [ATP + H2O -> ADP + Pi + E]
[A + B + ATP + H2O -> C + ADP + Pi]
Which is exergonic and which is endergonic? What happened to the energy?
1) hydrolysis of ATP
2) one of the endergonic reactants is phosphorylated (+ Pi)
3) the free energy and the reactants are combined to form the product and Pi is released (as it is not part of the product)
4) energy is used so the remaining products = C + ADP + Pi
Describe a REDOX reaction. What is reduction? Oxidation?
REDOX reaction is the combination/coupling of a reductive and oxidative process
Reduction is the gain/acceptance of one or more electrons
Oxidative is the loss/donation of one or more electrons
What are the two examples of electron carriers used in cellular respiration? Which form has the higher potential energy?
FAD is reduced to form FADH2 (has the higher PE)
FAD = flavin adenine dinucleotide
NAD+ is reduced into NADH (has the higher PE) + H
NAD = nicotinamide adenine dinucleotide