General Biology I (Chapter 6) Overview

Catabolism

Breaking down large molecules into smaller ones.

Energy

The capacity to do work.

Free Energy (ΔG)

Energy available to do work in a system.

Exergonic Reaction

A reaction that releases energy (negative ΔG).

Endergonic Reaction

A reaction that absorbs energy (positive ΔG).

ATP (Adenosine Triphosphate)

The main energy carrier in cells.

ADP (Adenosine Diphosphate)

ATP after losing one phosphate group.

Inorganic Phosphate (P)

A phosphate group released during ATP hydrolysis.

ATP Cycle

The continual process of ATP hydrolysis and synthesis.

Phosphorylation

The transfer of a phosphate group to a molecule.

Activation Energy

The energy required to initiate a chemical reaction.

Enzymes

Mostly proteins that speed up reactions.

Cofactors

Ions like Cu, Zn, Fe that help enzymes function.

Coenzymes

Molecules like FAD, ADP, riboflavin, folic acid that assist enzymes.

Competitive Inhibition

Inhibitor competes with the substrate at the active site.

Redox Reactions

Coupled processes that drive many cellular reactions.

Ribozyme

An RNA molecule with catalytic activity.

Cofactor

An ion or molecule required for enzyme activity.

Coenzyme

An organic molecule that assists enzyme function.

Apoenzyme

The protein part of an enzyme without its cofactor.

Holoenzyme

The complete, active enzyme (apoenzyme + cofactor).

Active Site

The region on an enzyme where substrate binding occurs.

Binding Site

The specific part of the active site that interacts with the substrate.

Catalytic Site

The area within the active site where the reaction is catalyzed.

Induced Fit

The change in enzyme shape upon substrate binding.

Substrate

The molecule upon which an enzyme acts.

Substrate Concentration

The amount of substrate available for reaction.

Optimal pH

The pH level at which an enzyme functions best.

Temperature Effect

Higher temperatures increase reaction rate until denaturation occurs.

Enzyme Denaturation

The loss of enzyme structure and function due to extreme conditions.

Enzyme Inhibition

The decrease in enzyme activity due to binding of inhibitors.

Noncompetitive Inhibition

Inhibitor binds to an allosteric site, altering enzyme activity.

Oxidation

Loss of electrons or hydrogen atoms.

Reduction

Gain of electrons or hydrogen atoms.

Redox Reaction

A chemical reaction involving both oxidation and reduction.

Kinetic Energy

Energy of motion.

Potential Energy

Energy stored within a system (e.g., chemical bonds).

First Law of Thermodynamics

Energy cannot be created or destroyed, only converted from one form to another.

Second Law of Thermodynamics

In any energy conversion, some energy is lost as heat, increasing the overall disorder (entropy).

Entropy

A measure of disorder or randomness in a system.

Metabolism

All chemical reactions that occur in an organism.

Anabolism

Building larger molecules (e.g., converting glucose molecules into starch).

Exergonic Reactions

Reactions with a negative ΔG that release energy (increase entropy and are spontaneous).

Endergonic Reactions

Reactions with a positive ΔG that absorb energy (decrease entropy and are nonspontaneous).