Lecture 14 Flashcards
What is Gibbs Free Energy?
The amount of energy in a system available to do work
What is the relationship of Gibbs free energy on endergonic and exergonic reactions?
Endergonic → positive Delta-G (products have more free energy than the reactants)
Exergonic → Negative Delta-G (reactants have more free energy than the products)
endergonic vs exergonic reactions
Endergonic Reaction:
Non-spontaneous
Positive Delta-G (products have more free energy than the reactants)
Require an input of energy
Exergonic Reaction:
Spontaneous
Negative Delta-G (reactants have more free energy than the products)
Release energy
Gibbs free energy equation for calculating ΔG
the relationship between Gibbs free energy and catabolism/anabolism.
Catabolism :
The products have less chemical energy than the reactants (-ΔH) and are more disordered (+ΔS)
Yields a negative ΔG
Anabolism :
The products have more chemical energy than the reactants (+ΔH) and are less disordered (-ΔS)
Yields a positive ΔG
the process of ATP hydrolysis
ATP + H2O → ADP + Pi
Describe the coupling of endergonic and exergonic reactions
the activation energy of a reaction and describe the role of enzymes
Activation energy = energy required to move a reaction to the transition state
Enzymes = reduce (lower) the activation energy by stabilizing the transition state
what is the active site of an enzyme?
Active site = region of an enzyme that binds the substrate and converts it to the product
Formation:
Amino acids that form the active site are often far apart in the linear sequences of unfolded enzymes
Protein folding brings specific amino acids close to each other to form the active site
Interactions between substrate and active site are typically noncovalent & help stabilize the transition state
Results in the decrease of activation energy
Describe and compare competitive inhibition, non-competitive inhibition, and allosteric activation
Competitive inhibition = the inhibitor competes with the substrate for binding to the active site
Non-competitve inhibition = the binding sites of the substrate and the inhibitor are different; binding of non-competitive inhibitor causes a decrease in the rate at which the enzyme converts the substrate to product
Allosteric activation = binding of a molecule to a site other than the active site in a way that promotes the binding of a substrate to the enzyme’s active site
Describe positive and negative feedback
Positive feedback =a mechanism of response in which a stimulus initiates reactions that amplify the stimulus
Negative feedback = a mechanism of response in which a stimulus initiates reactions that reduce the stimulus
