Energy and Enzymes in Biology

These flashcards cover key concepts related to forms of energy, thermodynamics, enzyme activity, and related biological processes.

Kinetic Energy

Energy of motion or the form of energy that is actually doing work.

Potential Energy

Stored energy, the capacity to perform work (theoretical energy).

Chemical Energy

Energy stored in the arrangement of atoms in chemical molecules.

First Law of Thermodynamics

Energy cannot be created or destroyed, only transformed.

Second Law of Thermodynamics

Energy naturally spreads out and systems move toward more randomness; energy is always lost as heat.

Isolated System

No energy enters or leaves; total energy remains constant inside.

Closed System

Energy can enter or leave but matter cannot.

Open System

Both energy and matter can enter or leave.

Spontaneous Reaction

A chemical reaction that occurs on its own without outside influence.

Change in Free Energy (∆G)

Determines spontaneity: negative ∆G is not spontaneous, positive ∆G is spontaneous.

Exergonic Reaction

A reaction where the potential energy of reactants is greater than that of products.

Endergonic Reaction

A reaction where the potential energy of reactants is less than that of products.

Catabolic Pathway

Reactions that break down molecules into smaller parts and release energy.

Anabolic Pathway

Reactions that build complex molecules from smaller ones and consume energy.

ATP Structure

A nucleotide made of adenine, ribose, and three phosphate groups.

ATP Hydrolysis

The reaction where the terminal phosphate is removed from ATP, releasing energy.

Coupling of Reactions

Endergonic reactions are powered by exergonic reactions.

Role of Enzymes

Speed up chemical reactions by lowering activation energy.

Lock-and-Key Hypothesis

The enzyme’s active site is a rigid shape that perfectly matches the substrate.

Induced-Fit Hypothesis

The enzyme’s active site changes shape to fit the substrate upon binding.

Optimal pH

The specific pH range where an enzyme exhibits maximum activity.

Effect of Low Temperature on Enzymes

Slows molecular movement, reduces reaction rate due to fewer collisions.

Effect of High Temperature on Enzymes

Denatures enzymes, causing them to lose their shape and active site.

Cofactor

A non-protein helper that many enzymes need to function.

Enzyme Activity Regulation

Cells can adjust the number of enzymes or use inhibitors to control reaction rates.

Enzyme Activity Curve

Graph showing enzyme activity against pH or temperature, with an optimum range.