Lecture Notes: ATP Production and Cellular Respiration

Vocabulary flashcards covering key terms and concepts from the lecture on ATP production, cellular respiration, and fermentation.

ATP

Adenosine triphosphate; the cell’s energy currency used to power chemical work, membrane transport, and mechanical work.

Cellular respiration

Process that breaks down glucose in the presence of oxygen to produce ATP, CO2, and H2O; includes glycolysis, pyruvate oxidation, citric acid cycle, ETC, and oxidative phosphorylation.

Glycolysis

First step of cellular respiration; occurs in the cytosol; anaerobic; splits glucose into two pyruvate molecules and nets 2 ATP and 2 NADH per glucose.

Pyruvate oxidation

Converts each pyruvate to acetyl-CoA in the mitochondria; releases CO2 and produces NADH; aerobic process.

Acetyl‑CoA

Two‑carbon acetyl group attached to coenzyme A; substrate that feeds the citric acid cycle.

Citric acid cycle (Krebs cycle)

Occurring in the mitochondrial matrix; acetyl‑CoA enters to form citrate and cycle products include CO2, NADH, FADH2, and ATP/GTP.

NAD+/NADH

Nicotinamide adenine dinucleotide; accepts electrons to become NADH; key electron carrier in respiration.

FAD/FADH2

Flavin adenine dinucleotide; accepts electrons to become FADH2; another electron carrier in respiration.

Electron transport chain (ETC)

Series of proteins in the inner mitochondrial membrane that transfer electrons from NADH/FADH2 to O2 and pump protons to create a gradient.

Oxidative phosphorylation

ATP production by using the proton gradient across the inner mitochondrial membrane via ATP synthase; powered by the ETC.

Substrate‑level phosphorylation

ATP formed directly in glycolysis and the citric acid cycle by transferring a phosphate to ADP via an enzyme.

Proton motive force

The electrochemical gradient of protons across the inner mitochondrial membrane that drives ATP synthesis.

Chemiosmosis

Movement of ions down their gradient across a membrane to drive ATP production; in respiration, protons flow through ATP synthase.

ATP synthase

Enzyme that uses the proton gradient to convert ADP and Pi into ATP.

Oxygen

Final electron acceptor in aerobic respiration; forms water when it accepts electrons and protons.

Water (H2O)

Product formed when oxygen accepts electrons and protons at the end of respiration.

CO2

Carbon dioxide produced when carbons are released from glucose during pyruvate oxidation and the citric acid cycle.

Cristae

folds of the inner mitochondrial membrane that increase surface area for more ETC machinery.

Mitochondria

Organelle powerhouse where aerobic respiration occurs; contains the matrix, inner membrane, and cristae.

NADH shuttle

NAD+ accepts electrons to form NADH and transports them to the ETC (also involves FADH2) for ATP production.

Fermentation

Anaerobic pathway regenerating NAD+ by converting pyruvate to lactate or to ethanol/CO2, allowing glycolysis to continue without oxygen.

Lactic acid fermentation

Pyruvate reduced to lactate; regenerates NAD+; occurs in muscle cells during intense exercise.

Ethanol (alcohol) fermentation

Yeasts convert pyruvate to ethanol and CO2; regenerates NAD+; used in brewing and baking.

Aerobic respiration

Respiration that requires oxygen; includes glycolysis (anaerobic step), pyruvate oxidation, citric acid cycle, and ETC.

Anaerobic respiration

ATP production without oxygen, using alternative electron acceptors or fermentation; less efficient than aerobic respiration.

Monosaccharide

Simple sugar; glucose is a monosaccharide; carbohydrate monomer.

Glycerol and fatty acids in metabolism

Fats contribute glycerol and fatty acids that feed into glycolysis and the acetyl‑CoA pool to help ATP production.

Glycolysis net yield

Net 2 ATP and 2 NADH per glucose; occurs in the cytosol and uses substrate‑level phosphorylation.

Pyruvate dehydrogenase

Enzyme complex that converts pyruvate to acetyl‑CoA in the mitochondria, releasing CO2 and generating NADH.

Intermembrane space

Space between the outer and inner mitochondrial membranes; proton gradient builds here during respiration.

Heat in respiration

Approximately 34% of energy is released as heat rather than captured as ATP.

Follow the carbons

A strategy to track carbon atoms through metabolic pathways to understand energy flow.

Monomer and polymer (carbohydrates)

Glucose is the monomer of carbohydrates; many units form polysaccharides built for energy storage and structure.