Mod 3: Ch 4-Energy and Metabolism Flashcards
Energy
The capacity to do work.
First Law of Thermodynamics
Energy cannot be created or destroyed.
Second Law of Thermodynamics
Energy tends to disperse spontaneously.
Potential Energy
Energy stored in the arrangement of objects in a system.
Reactants
A molecule that enters a chemical reaction and is changed by participating in it.
Products
A molecule that is produced by a chemical reaction.
Activation Energy
Minimum amount of energy required to start a chemical reaction.
Active Site
Pocket in an enzyme where substrates bind and a reaction occurs.
Substrate
Of an enzyme, specific molecule that can bind to the enzyme’s active site and be converted to a product. A reactant in an enzyme-mediated reaction.
Cofactors
A metal ion or small non-protein organic molecule that associates with an enzyme and is necessary for its function.
Coenzymes
An organic cofactor.
Phosphorylations
Chemical reaction in which an enzyme attaches a phosphate group to an organic molecule.
Metabolic Pathway
A series of enzyme-mediated reactions by which cells build, remodel, or break down an organic molecule.
Feedback Inhibition
Of a metabolic pathway, regulatory mechanism in which a reaction product slows or stops a pathway that produces it.
Electron Transfer Chains
Series of enzymes and other molecules in a cell membrane that accept and give up electrons in turn, thus releasing the energy of the electrons in steps.
Diffusion
The spontaneous spreading of molecules or atoms through a fluid or gas.
Hypotonic
Describes a fluid that has a low overall solute concentration relative to another fluid.
Hypertonic
Describes a fluid that has high overall solute concentration relative to another fluid.
Isotonic
Describes two fluids with identical solute concentrations.
Osmosis
Diffusion of water through a selectively permeable membrane.
Turgor Pressure
Pressure that a fluid exerts against a structure that contains it.
Facilitated Diffusion
Passive transport mechanism in which a solute follows its concentration gradient across a membrane by moving through a transport protein.
Passive Transport
Membrane-crossing mechanism that requires no energy input.
Active Transport
Energy-requiring mechanism in which a transport protein pumps a solute across a cell membrane against eh solute’s concentration gradient.
Exocytosis
Process by which a cell expels a vesicle’s contents to extracellular fluid.
Endocytosis
Process by which a cell takes in a small amount of extracellular fluid (as its contents) by the ballooning inward of the plasma membrane.
Phagocytosis
“Cell eating”; an endocytic pathway by which a cell engulfs a large particle such as another cell.
