ch. 8 Flashcards
Define Metabolism
the totality of an organism’s chemical reactions
What is a catabolic reaction?
releases energy by breaking down molecules.
What is an anabolic reaction?
absorbs energy by building molecules.
What is bioenergetics?
the study of how organisms manage their energy and resources.
What is thermodynamics?
the study of energy transformations.
What does the first law of thermodynamics state?
the energy of the universe is constant and is able to be transformed or transferred, but not created or destroyed.
What does the second law of thermodynamics state?
during every energy transfer, some energy is lost and increases the entropy of the universe.
What is entropy (∆S) and how does an increase in temp, enthalpy, and free energy affect it?
entropy is disorder. Increased temp causes increased entropy. Increased enthalpy causes decreased entropy. Increased free energy causes entropy to decrease.
What is enthalpy?
The amount of energy released or absorbed in a chemical reaction. So if ∆H is positive, it absorbs energy and if its negative it releases energy.
What is a spontaneous process?
Something that will happen given no external energy source (ex: ice melting)
How does ∆G affect spontaneity?
if ∆G is positive, it is nonspontaneous. If ∆G is negative, it is spontaneous.
What is free energy (∆G)?
the measure of a system’s instability and tendency to change to a more stable state.
What is an exergonic reaction?
releases free energy and is spontaneous.
What is an endergonic reaction?
absorbs free energy and is nonspontaneous
What is energy coupling?
the use of energy from an exergonic process to drive an endergonic one
How would you identify an ATP molecule?
it contains 3 phosphate groups
Where does the release of energy come from in ATP
the chemical change to a state of lower free energy
How does ATP drive endergonic reactions?
by phosphorylation which is transferring a phosphate group to another molecule to make it more favorable.
What happens in the hydrolysis of ATP?
breaks off a phosphate group
What is the difference between a catalyst and an enzyme?
An enzyme is a protein that specializes in speeding up a reaction while a catalyst is a general substance that speeds up a reaction.
What is activation energy?
The initial energy needed to start a chemical reaction
What is an enzyme-substrate complex?
when an enzyme binds to its substrate (reactant)
what is induced fit?
when the substrate and enzyme changes their shapes to bind to each other (like a handshake)
What can affect an enzyme’s activity?
temperature, pH level, or ionic concentrations
What is a cofactor?
nonprotein enzyme helpers (often ions)
What are coenzymes?
organic cofactors
What are competitive inhibitors?
they bind to the active site of an enzyme, competing with the substrate. (this does not denature the enzyme)
What are noncompetitive inhibitors?
they bind to another part of the enzyme which changes its shape and makes the active site less effective. (a type of allosteric regulation)
What is allosteric regulation?
The process in which a regulatory molecule binds to another part of an enzyme which can either make it more or less functional
What does the binding of an activator stabilize?
the active form of the enzyme
What does the binding of an inhibitor stabilize?
the inactive form of the enzyme
