An Introduction to Metabolism Flashcards
Metabolic Pathway
a series of defined steps (which are each catalyzed by a certain enzyme) which alters a specific molecule, resulting in a certain product
Catabolic Pathway
a metabolic pathway which releases energy via breakdown of complex compounds (ie: cellular respiration)
Anabolic Pathway
a metabolic pathway which consumes energy to build complex compounds (also called biosynthesis pathway)
Kinetic Energy
relative motion of objects
Thermal Energy
kinetic energy associated with random movement of atoms or molecules (such transfer from one object to other is called heat)
Potential Energy
An object is not moving and possesses energy due to its location or structure
Chemical Energy
the potential energy available for release in a chemical reaction (catabolic pathways harvest chemical energy)
First Law of Thermodynamics (the principle of conservation of energy)
Energy can be transferred and transformed, but it cannot be created or destroyed
Second Law of Thermodynamics
Every energy transfer or transformation increases the entropy of the universe
Free Energy
the portion of a system’s energy that can perform work when temperature and pressure are uniform
The Gibbs Free Energy Equation
Free Energy (Delta G) = The Change in Total Energy (Delta H) - Temperature in Kelvin * The Change in the Systems Enthalpy (Delta S)
Spontaneous Reaction
Unstable Systems like cells always become more stable (which explains diffusion and other phenomena), but never reach maximum stability, or equilibrium (such a stable state would mean work could not be performed, rendering the cell dead)
Exergonic Reaction
Energy outward (is a spontaneous reaction that does not require energy, Delta G is negative)
Endergonic Reaction
Energy Inward (is not spontaneous, energy required, Delta G is positive)
Chemical Work
The pushing of endergonic reactions that would not occur spontaneously (like the synthesis of polymers from monomers)
Transport Work
The pumping of substances across membranes against the direction of spontaneous movement (the concentration gradient)
Mechanical Work
the beating of cilia, the contraction of muscle cells, etc.
ATP Hydrolysis (Exergonic Reaction)
The bonds between the phosphate groups are broken through a dehydration reaction, ADP (Adenosine Diphosphate) is released
Energy Coupling
The use of an exergonic process to drive an endergonic process (cellular respiration drives many other chemical reactions)
Regeneration of ATP
ATP can be synthesized by adding a phosphate group to ADP, and uses the energy of catabolic processes to do so
Enzyme
a macromolecule that is a catalyst which speeds up a reaction without being consumed by the reaction
Activation Energy
the initial investment of energy required to start a reaction (which is absorbed by the molecules whose bonds are to be broken)
Transition State
The stage at which molecules have absorbed enough energy for their bonds to break
How Enzymes Speed Up Reactions
Enzymes lower the activation energy of the reaction (make molecules reach the transition state faster)
