Chapter 6: Energy and Enzymes

ECC Biology Chapter 6 Slides as Flashcards

Kinetic Energy

Kinetic Energy

-Energy of Motion

-Mechanical

Potential Energy

-Stored Energy

-Chemical Energy

Two Laws of Thermodynamics: First Law

-Law of conservation of energy

Two Laws of Thermodynamics: 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

Metabolism

-Sum of cellular chemical reactions in cell

-Reactants participate in a reaction

-Products form as result of a reaction

Free energy is the amount of energy available to perform work

-Exergonic Reactions: Products have less free energy than reactants (release energy)

-Endergonic Reactions: Products have more free energy than reactants (require energy input)

Adenosine triphosphate (ATP)

-High energy compound used to drive metabolic reactions

-Constantly being generated from adenosine diphosphate (ADP)

ATP Cont.: Composed of

-Adenine, Ribose (together = adenosine), and three phosphate groups

ATP cont.: Coupled reactions

-Energy released by an exergonic reaction captured in ATP

-ATP is used to drive an endergonic reaction

Reactions usually occur in a sequence

-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, and terminates with a particular end product

Enzyme

-Protein molecules that function as catalysts

-The reactants of an enzymatically catalyzed reaction are called substrates

-Each enzyme accelerates a specific reaction

-Each reaction in a metabolic pathway requires a unique and specific enzyme

-The end product will not be formed unless ALL enzymes in the pathway are present and functional

Energy of Activation: Molecules frequently do no react with one another unless they are activated in some way

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 substrates into contact with one another

Enzyme-Substrate Complex: The active complexes with the substrates

-Causes the active site to change shape

-SHape change forces substrates together, initiating bond

-Induced fit model

—Enzyme is induced to undergo a slight alteration to achieve optimum fit for the substrates