U2 Chapter 8: An Introduction to Metabolism Flashcards
Metabolism
The chemical changes that take place in a cell or an organism. These changes make energy and the materials cells and organisms need to grow, reproduce, and stay healthy. Metabolism also helps get rid of toxic substances
Metabolic Pathways
A set of actions or interactions between genes and their products that results in the formation or change of some component of the system, essential for the correct functioning of a biological system
Catabolic
Breaking down molecules, releasing energy
Anabolic
Building molecules, consuming energy
Bioenergetics
The study of the flow of energy through living organisms
Energy
The capacity to cause change; some forms of energy do work by moving matter
Kinetic Energy
Associated with motion and includes thermal energy which is associated with random motion of atoms or molecules
Heat
Thermal energy in transfer from one object to another
Potential Energy
Related to the location or structure of matter and includes chemical energy possessed by a molecule due to its structure
1st Law of Thermodynamics
Conservation of energy, states that energy cannot be created nor destroyed
2nd Law of Thermodynamics
States that spontaneous processes, those requiring no outside input of energy, increase the entropy (molecular disorder) of the universe
Free Energy
Energy that can do work under cellular conditions:
Change in Free Energy (<>G) = Enthalpy Change (<>H) - Change in Entropy (T<>S)
- organisms live at the expense of free energy
- at maximum stability, the system is at equilibrium and can do no work
Exergonic (spontaneous) Chemical Reaction
The products have less free energy than the reactants (neg <>G)
Endergonic (nonspontaneous) reactions
Requires and input of energy (pos <>G)
ATP
The cell’s energy shuttle
- Hydrolysis of its terminal phosphate yields ADP and Pi and releases free energy
Energy Coupling
The exergonic process of ATP hydrolysis drives endergonic reactions by transfer of a phosphate group to specific reactants, forming a phosphorylated intermediate that is more reactive
Activation Energy (Ea)
The energy needed to break the bonds of the reactants
- enzymes lower the Ea barrier
- each enzyme has a unique active site that binds to one or more substrate(s), the reactants on which it acts
- it then changes shape, binding the substrate(s) more tightly [induced fit]
Competitive Inhibitor
Binds to the active site
Noncompetitive Inhibitor
Binds to a different site on the enzyme
Allosteric Regulation
Regulatory molecules, either activators or inhibitors, bind to specific regulatory sites, affecting the shape and function of the enzyme
Cooperativity
Binding of one substrate molecule can stimulate binding or activity at other active sites
Feedback Inhibition
The end product of a metabolic pathway allosterically inhibits the enzyme for a previous step int he pathway
