Energy, ATP, and Enzymes

Energy

The ability to do work, that is, to move matter against opposing forces such as gravity and friction.

Kinetic Energy

The energy of motion.

Potential Energy

Stored energy, the capacity to do work.

Thermodynamics

The study of energy transformation.

First Law of Thermodynamics

Energy can be transferred and transformed, but it can neither be created nor destroyed.

Second Law of Thermodynamics

Every energy transfer or transformation increases the entropy of the universe.

Entropy

A measure of disorder or randomness in a system.

Free Energy (AG)

The portion of a system's energy that can perform work.

Exergonic Reaction

A process with a net release of free energy.

Endergonic Reaction

A process which absorbs free energy from the surroundings.

Energy Coupling

Using the energy released from an exergonic process to drive an endergonic process.

Mechanical Work

Work involving movements such as muscle contractions.

Transport Work

Pumping of molecules and ions across a plasma membrane against their concentration gradient.

Chemical Work

Pushing endergonic reactions that would not occur spontaneously.

ATP (Adenosine Triphosphate)

A close relative to Adenine that contains three phosphate groups.

Hydrolysis

The process by which ATP is broken down to release energy.

ADP (Adenosine Diphosphate)

The product formed when ATP loses one phosphate group.

Phosphorylated Intermediate

A molecule created when ATP transfers its phosphate group, which is usually more reactive.

Catalyst

A chemical agent that changes the state of a reaction without being consumed.

Substrate

The reactants in an enzyme-catalyzed reaction.

Cofactors

Helpers for enzymes that are often inorganic.

Enzymes

Protein catalysts that speed up reactions.

Transition State

A temporary state during a reaction where bonds are breaking and forming.

Activation Energy (EA)

The energy barrier that must be overcome for a reaction to occur.

Active Site

The region of an enzyme that binds to the substrate.

Induced Fit

The conformational change that occurs when an enzyme and substrate interact.

Enzyme-Substrate Complex

The intermediate formed when the enzyme binds to its substrate.

Performance Rate of Enzymes

The rate of reaction is proportional to substrate concentration but can saturate.

Denaturation

The process in which a protein loses its structure and function, often due to extreme conditions.

pH Optimum

The pH at which an enzyme performs at peak efficiency.

Cofactors

Non-protein molecules that help enzymes in their catalytic function.

Competitive Inhibitors

Molecules that compete for the active site on an enzyme.

Noncompetitive Inhibitors

Molecules that bind to an enzyme and change its shape, affecting substrate binding.

Enzyme Enhancers

Chemicals that increase enzyme function.

Allosteric Site

A site on an enzyme that is separate from the active site and can influence enzyme function.

Feedback Inhibition

A process by which the product of a pathway inhibits an enzyme involved in that pathway.

Threonine Deaminase

An example of an enzyme whose activity can be inhibited by its product, isoleucine.

Enzyme Action

The speed at which an enzyme catalyzes a reaction is influenced by environmental factors.

Temperature Optimum

The temperature at which an enzyme exhibits peak performance.

Isoleucine

An amino acid that acts as an inhibitor in feedback inhibition by binding to threonine deaminase.

Rate of Reaction

The speed at which reactants are converted to products in a chemical reaction.

Enzyme Specificity

The ability of an enzyme to choose exact substrates from a group of similar chemical molecules.

Hydrogen Bonds

Weak bonds that help stabilize enzyme-substrate complexes.

Ionic Bonds

Strong bonds that can also stabilize enzyme-substrate interactions.

Microenvironment

The specific environment created by the active site of an enzyme conducive to the reaction.

Temperature's Effect on Enzymes

Increasing temperature can speed up reactions but may also lead to enzyme denaturation.

pH's Effect on Enzymes

Extreme pH levels can denature enzymes, altering their function.

Nucleotide

A basic building block of DNA and RNA, of which ATP is an example.

Thermophilic Bacteria

Heat-tolerant bacteria which have enzymes with higher temperature optima.

Activation Energy Barrier

The amount of energy needed to initiate a reaction.

Enzyme Kinetics

The study of the rates of enzyme-catalyzed reactions.

Metabolism Control

Regulating the rates of metabolic reactions through enzyme inhibitors and activators.

Effector Molecules

Molecules that can enhance or inhibit enzyme activity.

Transition State Theory

A theory that explains the need for activation energy and the formation of the transition state.

Saturation in Enzymatic Reactions

When an increase in substrate concentration does not increase the rate of reaction.

Allosteric Regulation

Regulation of an enzyme by binding of an effector molecule at a site other than the active site.

Competitive Inhibition Example

A substrate analog that mimics the substrate and competes for the active site.

Noncompetitive Inhibition Example

The binding of a molecule to a site that alters the enzyme’s shape and function.

Catalytic Activity

The ability of an enzyme to catalyze a specific reaction.

Substrate Concentration

The amount of substrate present which influences the rate of enzyme reactions.

Regeneration of ATP

The process that replenishes ATP levels in cells, crucial for energy.

Reversible Inhibition

Inhibition that can be reversed, allowing enzyme function to return.

Irreversible Inhibition

Permanent inactivation of an enzyme, often due to covalent bonding.

Penicillin

An antibiotic that works through irreversible inhibition of bacterial enzymes.

Cyanide Poisoning

Caused by irreversible binding to cytochrome oxidase, inhibiting cellular respiration.

Energy Transformation

Conversion of energy from one form to another in biological systems.

Thermodynamic Laws

Rules governing the behavior of energy in systems, affecting biological processes.

Biochemical Pathways

Series of reactions catalyzed by enzymes, leading to product formation.

Ecosystem Energy Flow

How energy moves through living organisms and the environment.