lesson 10 Energetics and Enzymes

Flashcards covering key vocabulary terms related to energetics and enzymes, including definitions of metabolic processes, energy types, thermodynamics, enzyme function, and regulation mechanisms.

Metabolism

The sum total of chemical reactions that occur within a living organism to maintain life.

Catabolism

A metabolic process that breaks down complex molecules into simpler ones, releasing energy.

Anabolism

A metabolic process that uses energy to synthesize complex molecules from simpler ones.

ATP (Adenosine Triphosphate)

The molecule that serves as the primary energy currency of the cell, storing and transferring energy by transferring phosphate groups.

Thermodynamics

The study of energy, its transformation, and its relationship to work and heat.

Kinetic Energy

Energy that an object possesses due to motion or movement.

Potential Energy

Energy that is stored in an object or system as a result of position, shape, or state.

Free Energy

A thermodynamic concept that refers to energy that is available to do work.

Activation Energy

The minimum amount of energy that is needed for a chemical reaction to occur, representing the 'hump' on a free energy diagram.

First Law of Thermodynamics

States the conservation of energy: energy cannot be created or destroyed, but it can change form.

Second Law of Thermodynamics

States that in any isolated system, the total entropy (disorder) always increases over time.

Enthalpy

The total energy of a system.

Coupled Reactions

Two chemical reactions where the energy released from one reaction is used to drive the other reaction.

Phosphorylation

The addition of a phosphate group, which increases the potential energy of a molecule and can drive other chemical reactions.

Enzymes

Proteins and some RNA molecules that act as biological catalysts, accelerating chemical reactions by lowering activation energy.

Active Site

The specific region on an enzyme where the reaction occurs, shaped to fit a particular substrate molecule.

Enzyme Specificity

The characteristic where an enzyme's active site is shaped to fit only a particular substrate molecule with high affinity.

Enzyme Reaction Rate

The speed at which an enzyme increases a chemical reaction by lowering activation energy.

Optimal Range (Enzyme)

The specific range of conditions (e.g., pH and temperature) at which an enzyme exhibits its maximum catalytic activity.

Denaturation

A process in which the 3D structure of an enzyme is altered, causing it to lose its catalytic function, often due to extreme pH or temperature.

Saturation Point (Enzyme)

The point at which all enzyme active sites are occupied by substrate molecules, so increasing substrate concentration further does not increase reaction rate.

Transition State

The highest energy point in a reaction, representing the unstable shape reactants must be contorted into before converting to products.

Bioenergetics

The study of energy flow and transformation within living systems.

Metabolic Pathway

A step-by-step series of biochemical reactions that convert molecules into final products.

Photosynthesis

A process in producers where CO₂ + H₂O + sunlight are converted into glucose (C₆H₁₂O₆).

Cellular Respiration

A process in all life forms where Glucose (C₆H₁₂O₆) is broken down into CO₂ + H₂O + energy (ATP).

Dehydration Synthesis

An anabolic reaction where two molecules combine to form a larger one, releasing water and storing energy in bonds.

Hydrolysis

A catabolic reaction where a larger molecule is broken down into smaller ones by adding a water molecule, releasing energy.

Forward Hypothesis (Metabolic Pathway Evolution)

Hypothesis stating that new enzymes evolved step-by-step to build a pathway, extending from simple starting molecules to complex end products.

Retrograde Hypothesis (Metabolic Pathway Evolution)

Hypothesis stating that pathways evolved backward from essential end products, with new enzymes developing to replace missing environmental sources.

Electrochemical Gradients

A form of potential energy where ions build up on one side of a membrane, releasing kinetic energy when they flow back across.

Chemical Energy

Energy stored in the structure of molecules (potential) that is released during chemical reactions (kinetic).

Gibbs Free Energy (G)

The amount of usable energy available to do work during a metabolic reaction.

ΔG (Change in Gibbs Free Energy)

The change in usable energy for work after a chemical reaction.

ΔH (Change in Enthalpy)

The change in heat energy released or absorbed during a chemical reaction.

ΔS (Change in Entropy)

The change in energy lost to disorder during a chemical reaction.

Exergonic Reactions

Reactions that release energy (ΔG < 0), meaning products have less free energy than reactants. They are thermodynamically spontaneous.

Endergonic Reactions

Reactions that require an input of energy (ΔG > 0), meaning products have more free energy than reactants. They are not spontaneous.

Apoenzymes

Inactive enzymes that require nonprotein cofactors to become functional.

Cofactors

Nonprotein components (inorganic ions or organic coenzymes) required by apoenzymes for catalytic activity.

Coenzymes

Organic cofactors that assist enzymes in carrying out reactions.

Holoenzyme

A functional enzyme formed when an apoenzyme binds its cofactor(s).

Ribozymes

RNA molecules that possess catalytic activity.

Substrates

The specific reactants that an enzyme acts upon by binding to its active site.

Induced Fit

A model describing how an enzyme's active site slightly shifts shape upon substrate binding to optimize interaction, enhancing catalytic activity.

Michaelis-Menten Enzyme Kinetics

A model that explains how enzyme-catalyzed reaction rates change as substrate concentration increases.

V₀ (Initial Velocity)

The rate of product formation at a specific substrate concentration ([S]) in enzyme kinetics.

Vmax (Maximum Velocity)

The fastest rate an enzyme can achieve when fully saturated with substrate.

Km (Michaelis Constant)

The substrate concentration at which V₀ = ½ Vmax, reflecting the enzyme's affinity for its substrate (low Km = high affinity).

Allosteric Activation

A type of enzyme regulation where a cofactor binds to a regulatory site (not the active site), changing the enzyme's shape to enable substrate binding and activity.

Competitive Inhibitors

Molecules that resemble the substrate's shape and compete directly for binding to the enzyme's active site, preventing the actual substrate from attaching.

Noncompetitive Inhibitors

Molecules that bind to a separate regulatory site (allosteric site) on the enzyme, causing a conformational change that reduces the enzyme's effectiveness, independent of substrate concentration.

Feedback Inhibition

A form of negative regulation where the final product of a metabolic pathway binds to an enzyme early in the pathway, halting further production of the product.