Chapter 6: How Cells Release Energy - Vocabulary Flashcards

Vocabulary flashcards covering key terms and concepts from the notes on cellular respiration and related processes.

Cellular respiration

Process that breaks down glucose to produce ATP, CO2, and water.

ATP

Adenosine triphosphate; the cell's main energy carrier produced during respiration.

Aerobic cellular respiration

Respiration that requires oxygen and yields more ATP per glucose than anaerobic pathways.

Glucose

Initial substrate of cellular respiration that is split during glycolysis.

Oxygen

Final electron acceptor in the electron transport chain; required for aerobic respiration.

CO2

Carbon dioxide produced during the transition step and the Krebs cycle.

Water (H2O)

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

Glycolysis

Stage 1 of cellular respiration in the cytosol; splits glucose into two pyruvate, yielding 2 ATP (net) and 2 NADH.

Pyruvate

Three-carbon molecule produced by glycolysis; enters the transition step.

NADH

Electron carrier that stores energy and donates electrons to the electron transport chain.

NAD⁺

Oxidized form of NAD; accepts electrons to become NADH.

Transition step

Pyruvate is converted to acetyl CoA in the mitochondrial matrix, producing CO2 and NADH.

Acetyl CoA

Two-carbon acetyl group attached to CoA; substrate for the Krebs cycle.

Krebs cycle

Stage 2; occurs in the mitochondrial matrix; oxidizes acetyl CoA to CO2, generating NADH, FADH2, and ATP.

FADH₂

Electron carrier produced in the Krebs cycle that donates electrons to the ETC.

Electron transport chain (ETC)

Series of protein complexes in the inner mitochondrial membrane that transfers electrons to create a proton gradient and synthesize ATP.

Mitochondrion

Organelle where Krebs cycle and ETC occur; contains inner membrane and matrix.

Matrix

Internal fluid-filled space of the mitochondrion where Krebs cycle enzymes reside.

Intermembrane space

Space between the inner and outer mitochondrial membranes where protons are pumped.

ATP synthase

Enzyme that uses the proton gradient to synthesize ATP from ADP and Pi.

Chemiosmotic phosphorylation

ATP production driven by a proton gradient across a membrane.

Oxidative phosphorylation

ATP formation via the ETC and ATP synthase, powered by electron transport.

NADH and FADH₂

Electron carriers that donate electrons to the ETC.

Glycolysis location

Occurs in the cytosol (cytoplasm) of the cell.

Prokaryotes vs. Eukaryotes respiration locations

In prokaryotes, Krebs cycle occurs in the cytosol and ETC in the cell membrane; in eukaryotes, Krebs cycle occurs in the mitochondrial matrix and ETC in the inner mitochondrial membrane.

PGAL

Glyceraldehyde-3-phosphate; a 3-carbon intermediate in glycolysis.

1,3-bisphosphoglycerate

High-energy intermediate formed during glycolysis before substrate-level phosphorylation.

Substrate-level phosphorylation

Direct transfer of a phosphate from a substrate to ADP to form ATP (occurs in glycolysis).

Net ATP yield from glycolysis

Net production of 2 ATP per glucose after glycolysis (4 produced, 2 used).

Fermentation

Anaerobic process that allows glycolysis to continue by regenerating NAD+; no Krebs cycle or ETC.

Alcoholic fermentation

Pyruvate is reduced to ethanol with NAD+ regeneration.

Lactic acid fermentation

Pyruvate is reduced to lactate with NAD+ regeneration.

Anaerobic respiration

Respiration without oxygen using a non-oxygen electron acceptor; yields less ATP than aerobic respiration.

Endosymbiosis

Hypothesis that mitochondria and chloroplasts originated from engulfed bacteria.

Polysaccharides entering energy pathways

Glycogen and starch are broken down to glucose and feed glycolysis.

Proteins and fats entering energy pathways

Amino acids and fatty acids can be converted to pyruvate, acetyl CoA, or Krebs intermediates.

Glycolysis is anaerobic

Glycolysis does not require oxygen.

Oxygen as final electron acceptor

Oxygen accepts electrons at the end of the ETC to form water.

Total ATP yield per glucose (aerobic)

Theoretical yield of 36 ATP per glucose in aerobic respiration (2 from glycolysis, 2 from Krebs, 34 from ETC; minus 2 ATP for NADH transport).

End products of respiration

ATP produced, water formed, and CO2 released as waste.

Rotenone

Chemical that inhibits the first protein complex of the ETC; used to study respiration.

Uncoupler (e.g., DNP)

Compound that makes the inner mitochondrial membrane leaky to H+, uncoupling ETC from ATP synthesis and releasing energy as heat.