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Ch 8: An Introduction to Metabolism - Coggle Diagram
Ch 8: An Introduction to Metabolism
Matter and Energy
Metabolic Pathways
metabolism is the totality of an organism's chemical reactions, it arises from orderly interactions between molecules
in a metabolic pathway a specific molecule is altered in a series of defined steps, resulting in a certain product
each step is catalyzed by a specific enzyme, which is a macromolecule that speeds up a chemical reaction
catabolic pathways is a metabolic pathway that releases energy by breaking down complex molecules to simpler molecules (breakdown pathways)
anabolic pathways consume energy to build complicated molecules from simpler molecules
Forms of Energy
energy is the capacity to cause change, can be used to do work move matter against opposing forces, such as gravity and friction
kinetic energy is the energy of motion
thermal energy is kinetic energy associated with random movement of atoms or molecules
potential energy is energy that matter possesses because of its location or structure
chemical energy is potential energy that available for release in a chemical reaction
Laws of Thermodynamics
thermodynamics is the study of the energy transformations that occur in a collection of matter
the first law of thermodynamics states that energy can be transferred and transformed, but it cannot be created or destroyed
the first law is also known as the principle of conservation of energy
energy is transformed or transferred in living organisms some energy is lost as heat
the second law states every energy transfer or transformation increases the entropy of the universe
entropy is the molecular disorder of randomness
Free Energy
Free Energy, Stability, and Equilibrium
free energy is the portion of a system’s energy that can do work when temperature and pressure are uniform throughout the system, as in a living cell
the equation for free energy is ^G= ^H+- T^S (^ = delta)
G= Gibbs Free Energy, H= the change in enthalpy (total energy), T= the absolute temperature in Kelvin, and S= the change in entropy
if delta G is negative it is more spontaneous
if delta G is positive/ zero it’s nonspontaneous
Free Energy and Metabolism
exergonic reaction (energy outward) proceeds with a net release of free energy to the surroundings
endergonic reaction (energy inward) absorbs free energy from the surroundings
delta G is negative during exergonic reactions
cells manage energy resources to work through energy coupling is the use of an exergonic process to drive and endergonic one
Processes and Systems
spontaneous process occurs without an overall input of energy
it does not apply speed to the process, ex: rusting
nonspontaneous process needs additional energy to occur
there are more products than reactants, ex: boiling water on a stove
an isolated system is closed to surroundings
ex: a closed thermos with water
an open system is open to its surroundings
ex: living organisms
Enzymes
Activation Barrier
the investment of energy for starting a reaction is free energy of activation or activation energy (EA)
activation energy is the amount of energy that reactants must absorb before a chemical reaction will start
when the molecules have absorbed enough energy for the bonds to break, the reactants are in an unstable condition known as the transition state
Speed up Reactions
catalyst is a chemical agent that speeds up a reaction without being consumed by the reaction
an enzyme catalyzes a reaction by lowering the activation energy barrier which allows for the reactant molecules to absorb enough energy to reach the transition state
transition state is when the reactants are in an unstable condition
heat can increase the rate of a reaction by allowing reactants to attain the transition state more often
high temperature denatures proteins and kills cells, heat would speed up all reactions, not just those that are needed
Substrates
a substrate is the reactant in which an enzyme works
an enzyme substrate complex is a temporary complex formed when an enzyme binds to its substrate molecule
the reaction catalyzed by each enzyme is very specific, an enzyme can recognize its specific substrate even among closely related compounds
the active site is a specific region of an enzyme that binds to the substrate and forms the pocket in which catalysis occurs
Cofactors and Inhibitors
cofactors are any nonprotein molecule or ion that is required for the proper functioning of an enzyme
they can be permanently bound to the active site or may bind loosely and reversibly, along with the substrate, during catalysis
coenzymes are organic molecules serving as a cofactor
competitive inhibitors are substances that reduce the activity of an enzyme by entering the active site in place of the substrate
noncompetitive inhibitors are substances that reduce the activity of an enzyme by binding to a location remote from the active site, changing the enzyme’s shape so that the active site no longer effectively catalyzes the conversion of substrate to product