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Ch 8 - An Introduction to Metabolism, Sources: Urry, L. A., Cain, M. L.,…
Ch 8 - An Introduction to Metabolism
Metabolism Transforms Matter and Energy
Metabolism:
organism's chemical reactions, including catabolic and anabolic pathways
Metabolic Pathways:
series of chemical reactions that either builds a complex molecule or breaks down a complex molecule,
ex: glycolysis, photosynthesis
Catabolic Pathway:
metabolic pathway that releases energy by breaking down complex molecules,
ex: breakdown of glucose during cellular respiration
Anabolic Pathway:
metabolic pathway that consumes energy to synthesize a complex molecule from simpler molecules,
ex: photosynthesis
Bioenergetics:
overall flow and transformation of energy in an organism; study of how energy flows through organisms
Forms of Energy
Energy:
capacity to cause change, to do work (matter against opposing force)
Kinetic Energy:
energy associated with relative motion of objects, matter does work by passing on motion to other matter,
ex: water going through a dam turns turbines
Thermal Energy:
kinetic energy due to random motion of atoms/molecules; energy in most random form
Heat:
thermal energy. in transfer from one body of matter to another
Potential Energy:
energy that matter possesses as a result of its location or spatial arrangement,
ex: stretched rubber band
Chemical Energy:
energy available in molecules for release in a chemical reaction; form of potential energy,
ex: photosynthesis
Laws of Energy Transformation
Thermodynamics:
study of energy transformations that occur in a collection of matter
First Law of Thermodynamics:
principle of conservation of energy - energy can be transferred and transformed, not created or destroyed
Second Law of Thermodynamics:
principle stating that every energy transfer to transformation increases the entropy of the universe, usable forms are at least partly converted to heat
Entropy:
measure of molecular disorder or randomness
Spontaneous Process:
occurs without an overall input of energy, process that is energetically favorable
Free-Energy Change of Reaction
Free Energy:
perform work when temperature and pressure are uniform throughout the system, change in free energy of a system (change G) = change H - T change S, T = temperature, S = change in entropy
Exergonic Reaction:
spontaneous chemical reaction in which there is a net release of free energy,
ex: cellular respiration
Endergonic Energy:
non spontaneous chemical reaction in which free energy is absorbed from the surroundings,
ex: photosynthesis
ATP, Coupling Exergonic to Endergonic Reactions
Energy Coupling:
the use of energy released from an exergonic reaction to drive an endergonic reaction
ATP (adenosine triphosphate):
adenine-containing nucleoside triphosphate that releases free energy when its phosphate bonds are hydrolyzed; energy is used to drive endergonic
Phosphorylated Intermediate:
molecule with a phosphate group covalently bound, makes it more reactive than unphosphorylated molecule,
ex: formation of glucose-6-phosphate during initial steps of glycolysis
Enzymes
Enzyme:
macromolecule serving as a catalyst, increases the rate of a reaction without being consumed by the reaction,
ex: amylase
Catalyst:
chemical agent that selectively increases the rate of a reaction without being consumed by the reaction,
ex: enzymes
Catalysis:
process by which a chemical agent called a catalyst selectively increases the rate of a reaction without being consumed by the reaction
Activity of an enzyme its affected by pH and temperature
Activation Energy:
amount of energy that reactants must absorb before a chemical reaction will start; aka free energy of activation
Enzyme-Substrate Complex:
temporary complex formed when an enzyme binds to the substrate molecules,
ex: sucrase binding to sucrose
Active Site:
the specific region of an enzyme that binds the substrate and that forms the pocket in which catalysts occurs
Induced Fit:
caused by entry of the substrate, the change In shape of the active site of an enzyme so that it binds more snug
Coenzyme:
organic molecule serving as a cofactor,
ex: vitamins
Competitive Inhibitor:
substance that reduces the activity of an enzyme by entering the active site in place of the substrate
Noncompetitive Inhibitors:
reduces the activity of an enzyme by binding to a location remote from the active site - enzyme shape changes, active site no longer effectively catalyzes
Regulation of Enzyme Activity
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:
type of allosteric regulation; shape change in one subunit of a protein caused by substrate binding is transmitted to all other subunits
Feedback Inhibition:
method of metabolic control, end product of a metabolic pathway acts as a inhibitor of an enzyme within that pathway
Sources: Urry, L. A., Cain, M. L., Wasserman, S. A., Minorsky, P. V., & Reece, J. B. (2017). Campbell Biology (12th ed.). Pearson.