Metabolism Intro Notes

Forms of Energy
    Law of thermodynamics
    Metabolic reactions
ATP
Metabolic Pathways
-energy of activation-enzymes
-photosynthesis
-cellular respiration


2 Types of energy:
Kinetic
-energy of motion
-mechanical

Potential
-Stored energy
-chemical


Laws of Thermodynamics
First law:
-law of conservation of energy
-energy cannot be created or destroyed
-energy CAN be changed from one form to another
Second Law:
-Law of Entropy
-when energy is changed from one form to another, there is a loss of usable energy
-waste energy goes to increase disorder

Metabolic Reactions and Energy Transformations
Metabolism:
-sum of cellular chemical reactions in cell
-reactants participate in reaction
-products form as result of reaction
Free energy s the amount of energy available to perform work
-Exergonic Reactions-Products have less free energy than reactants
-Endergonic reactions-Products have more free energy than reactants

ATP and Coupled Reactions
Adensonine Triphosphate (ATP)
-High energy compound used to drive metabolic reactions
-constantly being generated from adenosine diphosphate (ADP)
Composed of:
-adenine and ribose (together=adensosine)
-three phosphate groups
Coupled reactions
-energy released by an exergonic reaction captured in ATP
-that ATP used to drive an endergonic reaction

ATP= ADP + P + Energy



Work-Related Functions of ATP
Primarily to perform cellular work
-Chemical work-Energy needed to synthesize macromolecules
-Transport work-Energy needed to pump substances across plasma membrane
-Mechanical work-Energy needed to contract

Metabolic Pathways
-Products of an earlier reaction become reactants of a later reaction
-Such linked reactions form a metabolic pathway
   -Begins with a particular reactant
   -Proceeds through several intermediates
   -Terminates with a particular end product

Enzymes
-Protein molecules that function as catalysts
-the reactants of an enzymatically accelerated reaction are called substrates
-each enzyme accelerates a specific reaction
-each reaction in a metabolic pathway requires a unique and specific enzyme
-end product will not appear unless ALL enzymes present and functional

Enzymes: Energy of Activation
Reactants often "reluctant" to participate in reaction
-energy must be added to at least one reactant to initiate the reaction
-energy of activation
Enzyme Operation:
-Enzymes operate by lowering the energy of activation
-Accomplished by bringing the substances


Irreversible Inhibition
Materials that irreversibly inhibit an enzyme are known as poisons
Cyanides inhibit enzymes resulting in all ATP production
Penicillin inhibits an enzyme unique to certain bacteria
Heavy metals irreversible bind with many enzymes
Nerve gas irreversibly inhibits enzymes required by nervous system