Chapter 8: An Introduction to Metabolism Flashcards
Metabolism
- All of an organism’s chemical reactions
- Consisting of catabolic and anabolic pathways, which manage the material and energy resources of the organelles
Metabolic Pathway
Series of chemical reactions that either builds a complex molecule or breaks down a complex molecule to simpler molecules
Catabolic Pathway
A metabolic pathway that releases energy by breaking down complex molecules to simpler compounds
Anabolic Pathway
Metabolic pathway that consumes energy to synthesize a complex molecule from simpler molecules
Bioenergetics
- Overall flow and transformation of energy in an organism
- Study of how energy flows through organisms
Energy
The capacity to cause change, especially to do work
Kinetic Energy
The energy associated with the relative motion of objects
Thermal Energy
- Kinetic energy due to the random motion of atoms and molecules
- Energy in its most random form
Heat
Thermal energy in transfer from one body of matter to another
Potential Energy
The energy that matter possesses as a result of its location or spatial arrangement (structure)
Chemical Energy
- Energy available in molecules for release in a chemical reaction
- A form of potential energy
Thermodynamics
The study of energy transformations that occur in a collection of matter
First Law of Thermodynamics
- The principle of conservation of energy
- Energy can be transferred and transformed, but it cannot be created or destroyed
Entropy
A measure of disorder or randomness
Second Law of Thermodynamics
- The principle stating that every energy transfer or transformation increases the entropy of the universe
- Usable forms of energy are at least partly converted to heat
Spontaneous Process
- A process that occurs without an overall input of energy
- A process that is energetically favorable
Free Energy
The portion of a biological system’s energy that can perform work when temperature and pressure are uniform throughout the system
Exergonic Reaction
A spontaneous chemical reaction in which there is a net release of free energy
Endergonic Reaction
A non-spontaneous chemical reaction in which free energy is absorbed from the surroundings
Energy Coupling
In cellular metabolism, the use of energy released from an exergonic reaction to drive an endergonic reaction
Adenosine Triphosphate (ATP)
- An adenine-containing nucleoside triphosphate that releases free energy when its phosphate bonds are hydrolyzed
- This energy is used to drive endergonic reactions in cells
Phosphorylated Intermediate
A molecule (often a reactant) with a phosphate group covalently bound to it, making it more reactive (less stable) than the unphosphorylated molecule
Enzyme
- Macromolecule serving as a catalyst
- Changes the rate of reaction without being consumed by the reaction
Catalyst
Chemical agent that speeds up a reaction without being consumed by the reaction
Activation Energy
- The amount of energy that reactants must absorb before a chemical reaction will start
- Also called free energy of activation
Substrate
The reactant on which an enzyme works
Enzyme-Substrate Complex
Temporary complex formed when an enzyme binds to its substrate molecule(s)
Active Site
- Specific region of an enzyme that binds the substrate
- Forms the pocket in which catalysis occurs
Induced Fit
- Caused by entry of the substrate
- Change in shape of the active site of an enzyme so that it binds more snugly to the substrate
Cofactor
- Any non protein molecule or ion that is required for the proper functioning of an enzyme
- Can be permanently bound to the active site or may bind loosely and reversibly, along with the substrate during catalysis
Coenzyme
- An organic molecule serving as a cofactor
- Most vitamins function as coenzymes in metabolic reactions
Competitive Inhibitor
Substance that reduces the activity of an enzyme by entering the active site in place of the substrate whose structure it mimics
Noncompetitive Inhibitor
- Substance that reduces the activity of an enzyme without entering an active site
- Binds elsewhere on the enzyme
- Changes the shape of the enzyme so the active site no longer effectively catalyzes the conversion of substrate to product
Allosteric Regulation
Binding of a regulatory molecule to a protein at one site that affects the function of the protein at a different site
Cooperativity
Kind of allosteric regulation whereby a shape change in one subunit of a protein caused by substrate binding is transmitted to all the other subunits, facilitating binding of additional substrate molecules to those subunits
Feedback Inhibition
Method of metabolic control in which the end product of a metabolic pathway acts as an inhibitor of an enzyme within that pathway
