BIO 110 Exam 3 Slide Vocab: Energy, Enzymes, and Cellular Metabolism

Comprehensive vocabulary flashcards covering thermodynamic principles, enzyme kinetics and regulation, and metabolic energy pathways from the BIO 110 Exam 3 review.

Redox Reactions

Reactions where electrons are transferred between two molecules.

Reduction

The process occurring when a molecule gains electrons.

Oxidation

The process occurring when a molecule loses electrons.

Energy

Capacity to do work or capacity for change; usually changes form during chemical reactions.

Chemical Reactions

Occurs when atoms collide with enough energy to combine or change their bonding partners.

Metabolism

Sum total of all chemical reactions occurring in a biological system at a given time.

Potential Energy

Stored energy (in chemical bonds, concentration gradient, or charge imbalance).

Kinetic Energy

Energy of movement.

Anabolic Reactions

Reactions in which complex molecules are made from simple molecules, requiring energy.

Catabolic Reactions

Reactions in which complex molecules are broken down into simple molecules, releasing energy.

Coupling of Catabolic and Anabolic Reactions

Energy released in catabolic reactions drives anabolic reactions.

Laws of Thermodynamics

Principles that apply to all matter and all the energy transformations in the universe.

First Law of Thermodynamics

Energy is neither created nor destroyed.

Second Law of Thermodynamics

When energy is converted from one form to another, some of that energy becomes unavailable to do work; no reaction is 100% efficient.

Entropy

Measure of disorder in a system.

Enthalpy ($H$)

Total energy.

Free Energy ($G$)

Usable energy that can do work.

Exergonic Reactions

Reactions that release free energy ($-\Delta G$), where the change in $G$ is negative.

Endergonic Reactions

Reactions that consume free energy ($+\Delta G$), where free energy is required and the change in $G$ is positive.

Catabolism

Process where complexity decreases, disorder is generated, and complex molecules are converted to free energy and small molecules.

Anabolism

Process where complexity/order increases, and free energy and small molecules are converted to complex molecules.

Chemical Equilibrium

Balance between forward and reverse reactions, where $\Delta G = 0$.

Catalyst

Increases the rate of a chemical reaction, is not altered by the reaction, and does not make a reaction occur that could not already occur.

Enzyme

Biological catalysts that act as a framework in which reactions can take place; most are proteins.

Activation Energy

Amount of energy required to start a reaction, which can come from heating the system.

Transition State

Reactive mode of the substrate after there has been sufficient input of energy to initiate the reaction.

Transition State Intermediates

Unstable reactants with higher free energy.

Substrates

Reactants; molecules on which an enzyme exerts its catalytic action.

Active Site

Place on an enzyme where the substrate binds.

Enzyme-Substrate Complex (ES)

An intermediate complex held together by hydrogen bonds, electrical attraction, or covalent bonds.

Induced Fit

Mechanism in which an enzyme changes shape when it binds substrate, altering the shape of the active site.

Prosthetic Groups

Non-amino acid groups bound to enzymes.

Inorganic Cofactors

Ions permanently bound to an enzyme.

Coenzymes

Small carbon-containing molecules that are not permanently bound to an enzyme.

Enzyme Inhibitors

Molecules that bind to an enzyme and slow reaction rates.

Naturally Occurring Enzyme Inhibitor

Inhibitor that regulates metabolism within biological systems.

Artificial Enzyme Inhibitors

Molecules that can be used to treat disease, kill pests, or study how enzymes work.

Irreversible Inhibition

Inhibition where an inhibitor covalently bonds to side chains in the active site and permanently inactivates the enzyme.

Reversible Inhibition

Inhibition where an inhibitor bonds non-covalently to the active site, preventing substrate binding (includes competitive, uncompetitive, and noncompetitive inhibitors).

Competitive Inhibitors

Inhibitors that compete with the natural substrate for binding sites on the enzyme.

Uncompetitive Inhibitors

Inhibitors that bind to the enzyme-substrate complex, preventing the release of products.

Noncompetitive Inhibitors

Inhibitors that bind to an enzyme at a site other than the active site, changing the enzyme shape.

Allosteric Regulation

Regulation occurring when an effector binds an enzyme at a site different from the active site, changing the enzyme's shape.

Active Form (Allosteric Regulation)

Conformation of an allosteric enzyme that can bind substrate.

Inactive Form (Allosteric Regulation)

Conformation of an allosteric enzyme that cannot bind substrate.

Commitment Step

The first reaction in a metabolic pathway, followed by other reactions in sequence.

Feedback Inhibition

A mechanism in which the final product of a pathway acts as a noncompetitive inhibitor of the first enzyme, shutting down the pathway.

Aerobic Respiration

The process of using glucose and oxygen to produce ATP, given by the reaction $C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + 32\,\text{ATP}$.

Photosynthesis Reaction

The metabolic process summarized by the reaction $6CO_2 + 6H_2O \xrightarrow{\text{Light Energy}} C_6H_{12}O_6 + 6O_2$.

Electron Carrier Molecules

Molecules that transport electrons in metabolic reactions, including NADH, $\text{FADH}_2$, and NADPH.

Glycolysis

An anaerobic 10-step catabolic pathway occurring in the cytosol that converts glucose into 2 molecules of pyruvate, consuming ATP in the first 5 steps and yielding 2 ATP and 2 NADH in the second 5 steps.

Pyruvate Oxidation

Metabolic pathway taking place in the mitochondrial matrix that converts pyruvate into acetate and $CO_2$.

Citric Acid Cycle

Metabolic pathway starting with acetyl CoA and oxidized electron carriers that yields $4CO_2$, $2\,\text{ATP}$, $6\,\text{NADH}$, and $2\,\text{FADH}_2$.

Oxidative Phosphorylation

The metabolic process in which ATP is synthesized by reoxidation of electron carriers in the presence of $O_2$, consisting of electron transport and chemiosmosis.

Electron Transport

Process in which electrons from NADH and $\text{FADH}_2$ pass through a respiratory chain of membrane-associated carriers.

Chemiosmosis

Process where protons flow back across the membrane through a channel protein, ATP synthase, which couples the diffusion with ATP synthesis.

Proton-Motive Force

Force generated across a membrane having two components: a chemical potential (difference in proton concentration) plus an electric potential due to the electrostatic charge on the proton.

Fermentation

An anaerobic process occurring in the cytoplasm of microorganisms and some vertebrate muscle cells without $O_2$; occurs as lactic acid or alcoholic fermentation.

Alcohol Fermentation

Anaerobic catabolic pathway that produces 2 ethanol, $2CO_2$, and 2 ATP.

Gluconeogenesis

Process in which glucose is formed from citric acid cycle and glycolysis intermediates.