Ch. 6 - An Introduction to Energy, Enzymes, and Metabolism Flashcards
ability to cause change or do work
Energy
energy associated with movement
Kinetic Energy
the energy that a substance or object possesses due to its structure or location
Potential Energy
the energy that is stored in atoms and in the bonds between atoms
Chemical Potential Energy
a form of electromagnetic radiation that is visible to the eye; packaged in photons.
Light Energy
the transfer of kinetic energy from one object to another or from an energy source to an object; viewed as kinetic energy that can be transferred due to a difference in temperature between two objects or locations
Heat Energy
the energy possessed by an object due to its motion or its position relative to other objects
Mechanical Energy
the movement of charge or the separation of charges can provide energy; a difference in ion concentration across a membrane creates an electrochemical gradient, which is a source of potential energy
Electrical/Ion Gradient Energy
energy cannot be created or destroyed; energy can be transferred and can be transformed from one type to another
First Law of Thermodynamics
any energy transfer or transformation from one form to another increases the degree of disorder of a system
Second Law of Thermodynamics
measure of randomness of molecules in a system
Entropy
total energy of a system
Enthalpy
usable energy - the amount of energy that is available and can be used to promote change or do work
Free Energy
free energy is released during product formation; spontaneous
Exergonic
positive free-energy change requiring the addition of free energy; not spontaneous
Endergonic
a phosphate is directly transferred from ATP to glucose
Phosphorylation
an agent that speeds up the rate of a chemical reaction without being permanently changed or consumed by it
Catalyst
an initial input of energy needed to overcome the repulsion of the electrons in the outer shells of atoms repelling each other
Activation Energy
when the original bonds have stretched to their limit; the chemical reaction can readily proceed to the formation of products
Transition State
location in an enzyme where the chemical reaction takes place
Active Site
reactant molecules that bind to an enzyme at the active site and participate in the chemical reaction
Substrates
the binding between enzymes and substrates
Enzyme-Substrate Complex
conformational changes cause the substrates to bind more tightly to the enzyme
Induced Fit
maximal rate when the enzyme is saturated with substrate
Vmax
substrate concentration at which the velocity is half its maximal value
Km
molecules that bind non-covalently to the active site of an enzyme and inhibit the ability of the substrate to bind
Competitive Inhibitors
decreasing the Vmax for the reaction without affecting the Km; binds non-covalently to an enzyme at a location outside the active site and inhibits the enzyme’s function
Noncompetitive Inhibitors
usually bind covalently to an enzyme to inhibit its function
Irreversible Inhibitors
small molecules that are permanently attached to the surface of an enzyme and aid in enzyme function
Prosthetic Groups
temporarily bind to the surface of an enzyme and promote a chemical reaction; ex. inorganic ions
Cofactors
organic molecules that temporarily bind to an enzyme and participate in the chemical reaction that the enzyme catalyzes, but are left uncharged when the reaction is completed
Coenzymes
chemical reactions are coordinated with each other and often occur in a series of steps with each step catalyzed by a specific enzyme
Metabolic Pathway
breakdown of larger molecules into smaller ones; often exergonic
Catabolic Reaction
involves the synthesis of larger molecules from smaller precursor molecules; usually endergonic
Anabolic Reaction
directly used to drive endergonic reactions in cells; ex. molecules like ATP; store energy from when cells break covalent bonds in organic molecules
Energy Intermediates
occurs when an enzyme directly transfers a phosphate from an organic molecule to ADP, thereby making ATP
Substrate-Level Phosphorylation
energy stored in an ion electrochemical gradient is used to make ATP from ADP & P
Chemiosmosis
the removal of one or more electrons from an atom or molecule
Oxidation
addition of one or more electrons to an atom or molecule
Reduction
when an atom or molecule is oxidized the electron that is removed must be transferred to another atom or molecule, which becomes reduced
Redox Reaction
slowest step of the metabolic pathway; if this step is inhibited or enhanced, such changes will have the greatest influence on the formation of the final product of the metabolic pathway
Rate-Limiting Step
time it takes for 50% of a specific type of molecule in a cell to be broken down and recycled
Half-life
enzymes that cleave the bonds between adjacent amino acids
Proteases
primary pathway for protein degradation in archaea and eukaryotic cells occurs via a protein complex; 4 stacked rings with 7 protein subunits each
Proteasome
cellular material becomes enclosed in a double membrane
Autophagy
when a double membrane is formed from a tubule that elongates and eventually wraps around the organelle
Autophagosome
