Define metabolism
the total of all chemical reactions done in an organism to store or release energy
Define metabolic pathway
begins with a specific molecule and ends with a product and is carried out by enzymes
Define catabolic pathways
release energy by breaking down molecules into simpler compounds
Define anabolic pathways
use energy to build molecules
Give an example of an anabolic pathway
synthesis of protein from amino acids to be used in muscles
Thermodynamics is the study of _________ ____________.
energy transformations
What is the 1st law of thermodynamics?
energy cannot not by created or destroyed, just transformed
What is the 2nd law of thermodynamics?
Every energy transfer increases the entropy (disorder) of the universe and makes things unstable. (energy will seek to get back into a stable form or equilibrium)
Define free energy
energy available to do work
If ∆G is negative, what happened?
energy was released (becomes more stable)
If ∆G is positive, what happened?
energy was stored (becomes less stable)
Releasing free energy is known as a ___________ ______
spontaneous change
The energy released in a spontaneous change do what?
be harnessed to do work
Define endergonic reaction
absorbs free energy from its surroundings and is nonspontaneous. (Anabolic)
Define exergonic reaction
proceeds with a net release of free energy and is spontaneous. (Catabolic)
Define energy coupling
the use of an exergonic process to drive an endergonic one
Most energy coupling in cells is done how?
by ATP
ATP is made of what?
ribose (a sugar), adenine (a nitrogenous base), and three phosphate groups.
ATP powers cells how?
By breaking off a phosphate group. This lowers free energy and releases energy. (exergonic)
The released phosphate in ATP does what?
combines with a reactant to make it unstable.
Why is phosphorylation useful?
It is an endergonic reaction which makes the recipient molecule unstable with extra stored energy and able to do work.
Name the exergonic process in ATP
Dephosphorylation
Name the endergonic process in ATP
Phosphorylation
Define phosphorylation
When the released phosphate in ATP combines with a reactant
Define catalyst
chemical agent that speeds up a reaction
What is a catalytic protein
enzyme
Define activation energy
The initial energy needed to start a chemical reaction
Define substrate
reactant that an enzyme acts on
Define substrate complex
enzyme and substrate together
Active site
part of the enzyme the substrate binds to
Define induced fit
“lock and key” matching shape of enzyme and substrate
The active site can lower an EA barrier by
- Orienting substrates correctly
- Straining substrate bonds
- Providing favorable pH
- Covalently bonding to the substrate
nonprotein enzyme helpers
cofactors
An organic cofactor
coenzyme
Define competitive inhibitors
bind to the active site of an enzyme, competing with the substrate
Define noncompetitive inhibitors
bind to another part of an enzyme, causing the enzyme to change shape and making the active site less effective
Enzyme activity is controlled to regulate __________.
metabolism
Define allosteric regulation
occurs when a regulatory molecule binds to a protein at one site and affects the protein’s function at another site.
make enzymes inactive
Inhibitors
make enzymes active
Activators
cooperativity
a form of allosteric regulation where the presence of the substrate makes the enzyme active.
feedback inhibition
the end product of a metabolic pathway shuts
down the pathway.
ΔS is what?
entropy
What is the equation for free energy?
ΔG=ΔH-TΔS
ΔH is what?
Enthalpy
Define enthalpy
The energy to break or release a bond
ΔH
exothermic reaction
ΔH>0 means what
endothermic reaction
