chapter 6 Flashcards
Metabolism
The totality of an organisms chemical reactions.
Metabolic Pathways
Begin with a specific molecule and ends with a product. Each step is catalyzed by a specific enzyme.
Catabolic Pathways
Release energy by breaking down complex molecules into simpler molecules.
Anabolic Pathways
Consume energy to build complex molecules from simpler ones.
Bioenergetics
The study of how energy flows through living organisms.
Work
The movement of matter against opposing forces.
Thermodynamics
The study of energy transformations.
1st law of thermodynamics
Energy can be transferred and transformed but it cannot be created or destroyed.
2nd law of thermodynamics
Entropy can only increase or stay the same in a closed system.
Entropy
A measure of molecular disorder.
Spontaneous Processes
Occur without energy input. Must increase the entropy of the universe and be moving towards equilibrium.
Free Energy
The portion of a system’s energy that can do work when temperature and pressure are uniform throughout, as in a living cell. A measure of a systems instability.
Exergonic Reaction
Proceeds with a net release of free energy and is spontaneous.
Endergonic Reaction
Absorbs free energy from its surroundings and is nonspontaneous.
Energy Coupling
The use of an exergonic reaction to drive an endergonic one. How cells do work.
ATP (adenosine triphosphate)
Composed of a ribose (a sugar), adenine (a nitrogen base), and a chain of three phosphate groups.
Phosphorylation
Transferring a phosphate group to another molecule, such as a reactant.
Catalyst
A chemical agent that speeds up a reaction without being consumed by the reaction.
Enzyme
A macromolecule that acts as a catalyst. Most are proteins.
Activation Energy
The energy required to start a reaction by breaking bonds in the reactant molecules.
Substrate
The reactant molecule on which an enzyme acts.
Active Site
The region on the enzyme to which the substrate binds.
Induced Fit
Enzymes change shape due to chemical interactions with the substrate. Brings chemical groups of the active site together.
Enzyme Inhibition
Enzyme activity is regulated by molecules that selectively inhibit enzyme function.
Competitive Inhibitors
Bind to the active site of an enzyme and prevent the substrate from binding.
Noncompetitive Inhibitors
Bind to an alternate site on the enzyme, causing the active site to change shape and become less effective.
Allosteric Regulation
May either inhibit or stimulate an enzyme’s activity. Occurs when a regulatory molecule binds to a protein at one site and affects the protein’s function at another site.
