Chapter 8 - Metabolism Flashcards
Pathway that begins with a certain molecule which is then altered in a series of defined steps, resulting in a certain product; each step is catalyzed by a specific enzyme
Metabolic pathway
Totality of an organism’s chemical reactions
Metabolism
Degradative processes; breakdown pathways
Catabolic pathways
Consume energy to build complicated molecules from smaller ones; bio synthetic pathways
Anabolic pathways
Study of how energy flows through living organisms
Bioenergetics
Capacity to cause change
Energy
Energy of motion
Kinetic energy
Energy based on an object’s structure or location
Potential energy
Energy associated with the random movement of atoms or molecules
Thermal energy
Thermal energy in transfer from one object to another
Heat
Potential energy available for a chemical reaction
Chemical energy
Study of energy transformations that occur in a collection of matter
Thermodynamics
The energy of the universe is constant: “Energy can be transformed or transferred but not created or destroyed.”
First law of thermodynamics
Quantity used to measure disorder, randomness
Entropy
“Every energy transfer or transformation increases the entropy of the universe.”
Second law of thermodynamics
A process that by itself leads to an increase in entropy that can proceed without requiring the input of energy
Spontaneous process
Portion of the system’s energy that can perform work when temperature and pressure are uniform throughout a system
Free energy
Energy outward; proceeds with a net release of free energy
Exergonic reaction
Energy inward; absorbs free energy from its surroundings
Endergonic reaction
Use of an exergonic reaction to drive an endergonic one
Energy coupling
Ribose with adenine and a chain of 3 phosphate groups bonded to it; plays a role in energy coupling and the making of RNA
ATP
A molecule with a phosphate group covalently bonded to it making it more reactive than an unphosphorylated molecule
Phosphorylated intermediate
A macromolecule (protein) that acts as a catalyst
Enzyme
Chemical agent that speeds up a reaction without being consumed by the reaction
Catalyst
Initial investment of energy for starting a reaction; the energy required to contort the reactant molecules so the bonds can break
Activation energy
The reactant an enzyme acts on
Substrate
The enzyme bound to a substrate that while they are joined, the catalytic action of the enzyme converts the substance to the product of the reaction
Enzyme-substrate complex
Restricted region of the enzyme molecule that actually binds to the substrate; typically a pocket or groove on the surface of the enzyme where catalysis occurs
Active site
Caused by the entry of the substrate, the change in shape of the active site of an enzyme so that it binds more snugly to the substrate
Induced fit
Nonproteins that help enzymes with catalytic activity; they may be bound tightly to the enzyme as permanent residents or loosely and reversibly along with the substrate
Cofactors
Organic molecule cofactor
Coenzyme
Reversible inhibitors that resemble the normal substrate molecule and compete for admission to the active site
Competitive inhibitors
Do not directly compete with the substrate to bind to the enzyme at the active site
Noncompetitive inhibitors
Any case in which a protein’s function at one site is affected by the binding of a regulatory molecule to a separate site; may result in either inhibition or stimulation of an enzyme’s activity
Allosteric regulation
A kind of allosteric activation where a substrate molecule binding to one active site in a multisubunit enzyme triggers a shape change in all the subunits, thereby increasing catalytic activity at the other active sites
Cooperativity
Common mode of metabolic control in which a metabolic pathway is halted by the inhibitory binding of its end product to an enzyme that acts early in the pathway
Feedback inhibition
