Unit 3: Bioenergetics, Enzymes, and Cellular Respiration

Vocabulary practice flashcards covering thermodynamics, enzyme kinetics and regulation, redox reactions, and the stages and products of cellular respiration.

Kinetic Energy

The energy of motion, exemplified at the cellular level by the diffusion of molecules across a membrane.

Potential Energy

Stored energy possessed by an object due to its position or state, such as standing stationary on the edge of a cliff before jumping.

First Law of Thermodynamics

The principle that energy cannot be created or destroyed, only transformed from one form to another, such as solar panels converting sunlight into electrical energy.

Enzyme

A biological catalyst that accelerates chemical reactions without being consumed, allowing it to function repeatedly once an initial reaction completes.

Competitive Inhibitor

A regulatory molecule that binds directly to an enzyme's active site, physically blocking the substrate from binding.

Hexokinase

The initial enzyme of glycolysis that catalyzes the conversion of glucose into glucose-6-phosphate.

Enzyme Optimal pH

The specific pH level at which a given enzyme exhibits its maximum catalytic activity, varying depending on the specific enzyme.

Induced Fit

The conformational change in the shape of an enzyme's active site induced by substrate entry, enabling the substrate to bind snugly.

Oxygen (in the ETC)

The highly electronegative terminal molecule in cellular respiration that serves as the final electron acceptor in the electron transport chain.

Oxidation

A chemical reaction involving the loss of one or more electrons, such as the conversion of a neutral sodium atom ($Na$) into a sodium ion ($Na^+$).

Reduction

A chemical reaction involving the gain of one or more electrons, such as the conversion of a neutral chlorine atom ($Cl$) into a chloride ion ($Cl^-$).

Glycolysis

The universal metabolic pathway that breaks down glucose to harvest energy, serving as the first step for both aerobic and anaerobic ATP production.

Products of Pyruvate Oxidation

The molecules generated from pyruvate processing prior to the citric acid cycle: 2-acetyl CoA, $2\text{ NADH}$, $2\text{ H}^+$, and $2\text{ CO}_2$.

Products of Glycolysis

The net output produced from breaking down glucose: 2 pyruvate, $4\text{ ATP}$, $2\text{ NADH}$, $2\text{ H}^+$, $2\text{ ADP}$, and $2\text{ P}_i$.

Products of the Krebs/Citric Acid Cycle

The molecules generated per glucose molecule: 2 CoA, $4\text{ CO}_2$, 2 oxaloacetate, $6\text{ NADH}$, $6\text{ H}^+$, $2\text{ FADH}_2$, and $2\text{ ATP}$.

Products of Oxidative Phosphorylation

The final stage outputs of cellular respiration: $10\text{ NAD}^+$, $2\text{ FAD}^+$, $24\text{ H}^+$, $32\text{ ATP}$, and $6\text{ H}_2\text{O}$.

ATP Synthase

The enzyme complex that synthesizes ATP driven by the flow of protons down an electrochemical gradient created by chemiosmosis during oxidative phosphorylation.

Exergonic Reaction

A spontaneous chemical reaction that releases free energy ($\Delta G < 0$), exemplified by cellular respiration.

Endergonic Reaction

A non-spontaneous chemical reaction that requires an input of free energy ($\Delta G > 0$), exemplified by photosynthesis.

Catalyst

A chemical agent that accelerates the rate of a reaction by lowering its activation energy ($E_A$) without altering the free energy change ($\Delta G$).