AP Biology: Respiration & Membrane Transport Flashcards

Comprehensive vocabulary flashcards covering the stages of cellular respiration, bioenergetics, cellular transport mechanisms, and plasma membrane dynamics.

Cellular Respiration

The cellular process that breaks down glucose to generate $\text{ATP}$ (adenosine triphosphate), which serves as the primary energy currency of life.

Aerobic Respiration

A cellular pathway requiring oxygen to fully break down glucose into energy, governed by the chemical reaction $C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{ATP} + \text{Heat}$.

Anaerobic Respiration / Fermentation

A process occurring without oxygen where cells execute Glycolysis followed by fermentation to recycle $NAD^+$ back from $NADH$, allowing continuous $\text{ATP}$ production.

Lactic Acid Fermentation

An anaerobic pathway in animal muscle cells during intense exercise that converts glucose to lactic acid and $2\,\text{ATP}$.

Alcoholic Fermentation

An anaerobic pathway in yeast and plant cells used in baking and brewing that converts glucose into ethanol, $CO_2$, and $2\,\text{ATP}$.

Glycolysis

An evolutionary, anaerobic pathway in the cytosol that splits one 6-carbon glucose into two 3-carbon pyruvate molecules, yielding $2\,\text{NADH}$ and $2\,\text{Net ATP}$ via substrate-level phosphorylation.

Pyruvate Oxidation

The pathway in the mitochondrial matrix that converts $2$ pyruvate molecules into $2$ Acetyl-CoA, producing $2\,NADH$ and releasing the first metabolic $CO_2$.

Krebs Cycle (Citric Acid Cycle)

A high-efficiency oxidation stage in the mitochondrial matrix that processes Acetyl-CoA to load electron carriers, producing $4\,CO_2$, $6\,NADH$, $2\,FADH_2$, and $2\,\text{ATP}$.

Electron Transport Chain (ETC) & Chemiosmosis

A pathway in the inner mitochondrial membrane that uses high-energy electrons from $10\,NADH$ and $2\,FADH_2$ to power proton pumps, creating a gradient that drives ATP Synthase to generate $\sim 28\text{ to }32\,\text{ATP}$.

Simple Diffusion

The passive movement of solute particles directly through the phospholipid bilayer from high to low concentration without requiring energy ($\text{ATP}$).

Facilitated Diffusion

The passive movement of specific molecules down their concentration gradient using channel or carrier proteins without requiring energy ($\text{ATP}$).

Active Transport

The movement of molecules against their concentration gradient (low to high concentration), requiring energy ($\text{ATP}$) and specialized protein pumps.

Sodium-Potassium Pump ($Na^+/K^+$ ATPase)

A membrane protein pump that uses active transport to export $3\,Na^+$ ions and import $2\,K^+$ ions into nerve cells to maintain an electrical charge.

Redox Reaction

A reduction-oxidation reaction; in cellular respiration, glucose is oxidized to $CO_2$ (loses electrons/hydrogens) and oxygen is reduced to $H_2O$ (gains electrons/hydrogens).

Proton-Motive Force

An acidic gradient created by actively pumping $H^+$ ions into the intermembrane space, driving their diffusion back into the matrix exclusively through ATP Synthase.

Cyanide / Azide Disruption

A chemical disruption that blocks the final ETC complex, halting electron transit and $H^+$ pumping, collapsing the gradient, and stopping $\text{ATP}$ generation.

Uncouplers (DNP / Thermogenin)

Molecules that make the inner mitochondrial membrane permeable to $H^+$ ions, bypassing ATP Synthase and causing free energy to be released strictly as heat.

Secondary Active Transport (Cotransport)

A transport mechanism where a primary pump uses $\text{ATP}$ to create an ion gradient, which a cotransporter then uses to pull a target molecule against its concentration gradient.

Surface-Area-to-Volume Ratio (SA:V)

A physical ratio that decreases as cells enlarge because volume scales cubically while surface area scales quadratically, dropping diffusion efficiency relative to metabolic demand.

Water Potential

A measure governed by $\Psi = \Psi_s + \Psi_p$ that determines passive water movement from high to low potential, where solute potential is given by $\Psi_s = -iCRT$.