Enzymes and Kinetics Flashcards
What is free energy (G)?
Portion of a system’s energy that can do work.
What does it mean if a system in its final state has less free energy?
More stable
What is the equation for free energy?
G(final) - G(initial)
If the overall change of G is ____ it is a spontaneous change.
Negative
What is an exergonic reaction?
Net release of energy
What is an endergonic reaction?
Net input of energy
What is the name of the state where bond breaking and bond forming occurs?
Transition state
Intitial energy needed to start chemical reactions is called what?
Activation Energy
How do cells handle thermal energy?
Denature if too high or speed up all reactions spontaneously
What is a catalyst?
Selectively speeds up reactions without being consumed by the reaction
What is an enzyme?
Catalytic protein that lowers the activation energy of a reaction
Does adding an enzyme change the free energy (G)?
NO
What is the name of the reactant used by enzymes?
Substrate
What is the active site?
Place where the substrate binds to the enzyme and the reaction occurs
What are the type of bonds in an active site?
Ionic or H-bonding
What is induced fit?
Conformational change to grab onto substrate
What is the name of the structure that contains both an enzyme and substrate?
Enzyme-substrate complex
How does an active site lower activation energy? (4)
- orienting 2+ substrates correctly
- Straining substrate bonds- distorts substrate
- Providing favorable microenvirnoments
- Temporary covalent bonding with the substrate
True or false… Enzymes change in a reaction
FALSE
How do you increase the rate of reactions in enzymes?
Increase the concentration
What does it mean if a enzyme is saturated?
All the enzyme molecules have active sites in use
How do you reduce saturation?
Add more enzymes to an area
What can effect enzyme activity? Define or give example of each
- Physical and chemical conditions- temerature and pH
- Cofactors- promote function- Metal ions, vitamins, small molecules
- Inhibitors- block function of enzyme
- Change primary structure- alter the sequence of the amino acids
What are competitive inhibitors?
Compete for substrate bonding site
What are noncompetitive inhibitors?
Do not bind to the active site but will change the shape of the acitve site to stop function.
What is the order of an enzyme cycle? (6)
- Substrate enters active site
- Substrates are held in active site by weak interactions
- The active site lowers Ea
- Substrates are converted to products
- Products are released
- Active site now available for new substrate
