Chapter 6.5 Enzymes Study Reviewer

Vocabulary flashcards covering core enzyme concepts, specificity models, environmental sensitivities, regulation mechanisms, helper molecules, and cellular control.

Enzymes

Special molecules (almost all are proteins made of amino acid chains) that act as biological catalysts to help chemical reactions occur.

Activation Energy

The energy required for chemical reactions to occur, which enzymes lower by binding to reactants and facilitating bond-breaking and bond-forming.

Free Energy ($\Delta G$)

The overall thermodynamic energy of a chemical reaction, which is not changed or altered by enzymes.

Substrates

The chemical reactants to which enzymes bind.

Active Site

The specific location within an enzyme where substrates bind and catalysis takes place, featuring a unique combination of amino acid residues.

Induced-Fit Model

A model describing a dynamic interaction where the enzyme and substrate undergo a mild structural shift upon binding to achieve an ideal fit.

Denaturation

The process where extreme environmental conditions, such as extreme temperature or pH, disrupt enzyme structure and active site residues, preventing proper binding.

Competitive Inhibition

A regulatory mechanism where an inhibitor molecule closely resembles the substrate and competes for the active site, blocking substrate entry and affecting the initial reaction rate.

Noncompetitive Inhibition

A regulatory mechanism where an inhibitor binds to an allosteric site, inducing a conformational change that prevents substrate binding and affects the maximal reaction rate.

Allosteric Site

A specific location on an enzyme other than the active site where noncompetitive inhibitors or regulatory molecules bind.

Allosteric Regulation

A process where allosteric inhibitors reduce enzyme affinity for substrates across multiple protein subunits, while allosteric activators increase substrate affinity.

Cofactors

Inorganic ions (such as iron $Fe^{2+}$, magnesium $Mg^{2+}$, and zinc $Zn^{2+}$) that act as non-protein helper molecules required for proper enzyme function.

Coenzymes

Organic non-protein helper molecules, primarily sourced from dietary vitamins (such as Vitamin C), required for proper enzyme function.

Compartmentalization

A cellular strategy in eukaryotic cells where specific enzymes are housed inside organelles (like mitochondria or lysosomes) to isolate processes and optimize reactions.

Feedback Inhibition

A regulatory mechanism where the end product of a metabolic pathway acts as an inhibitor to an upstream enzyme, halting excess production when product levels are high.