Enzymes Flashcards
The study of energy transformations
Thermodynamics
Energy can be transferred and transformed, but it cannot be created or destroyed
1st Law of Thermodynamics
During every energy transfer or transformation, some energy is unusable and is often lost as heat.
2nd Law of Thermodynamics
Every energy transfer or transformation increases the entropy of the universe.
2nd Law of Thermodynamics
A measure of a system’s instability, its tendency to change to a more stable state.
Free energy
True or False
Cells are in equilibrium
False
____ release energy by breaking down complex molecules into simpler compounds.
Catabolic Pathways
____ consume energy to build complex molecules from simpler ones.
Anabolic Pathways
What type of reaction is this?
Exergonic
Spontaneous
What kind of reaction is this?
Endergonic
Not spontaneous
Energy that can do work when temperature and pressure are uniform
Free energy
A ____ reaction generates energy
Exergonic
Spontaneous
A ____ reaction requires energy
Endergonic
Not spontaneous
ΔG is negative for all ____ processes.
spontaneous
Processes with zero or positive ΔG are ___
Never spontaneous
The initial energy needed to start a chemical reaction is called the
Activation Energy
True or False
A catalyst is consumed on completion of a reaction.
False
Enzymes__do/do not__ affect the change in free energy
do not
Begins with a specific molecule and ends with a product
Metabolic Pathway
Occur without energy input
Spontaneous Processes
Increase the entropy of the universe
Spontaneous Processes
Processes that decrease entropy
Nonspontaneous
ATP is comprised of
- Ribose
- Adenine
- 3 Phosphate groups
When the terminal phosphate bond of ATP is broken
Energy is released
A cell’s three types of work
- Chemical
- Transport
- Mechanical
The use of an exergonic process to drive an endergonic one
Energy coupling
ATP hydrolysis can be used to power ____ reactions
non-spontaneous
The reactant that an enzyme acts on is
The substrate
Tthe region on the enzyme where the substrate binds
The active site
Brings chemical groups of the active site into positions that enhance their ability to catalyze the reaction
Induced fit
The rate of an enzyme-catalyzed reaction can be sped up by increasing
Substrate concentration
When all enzyme molecules have their active sites engaged
The enzyme is saturated
Nonprotein enzyme helpers
Cofactors
An organic cofactor is called a ___
coenzyme
An inactive enzyme without the cofactor is called an
apoenzyme
A complete enzyme with cofactor is called a
holoenzyme
Bind to the active site of an enzyme, competing with the substrate
Competitive inhibitors
Bind to another part of an enzyme, causing the enzyme to
change shape and making the active site less effective
Noncompetitive inhibitors
When a regulatory molecule binds to a protein at one site and affects the protein’s function at another site
Allosteric regulation
What is feedback inhibition?
The end product of a metabolic pathway shuts down the pathway
A form of allosteric regulation that can amplify enzyme activity
Cooperativity
One substrate molecule primes an enzyme to act on additional substrate molecules more readily
Cooperativity
