Cellular Respiration - AP Biology

Final electron acceptor. Receives electrons from ETC, allowing electron flow to continue.

Pyruvate oxidation (acetyl-CoA formation). Pyruvate is decarboxylated and combined with coenzyme A.

Pyruvate oxidation and the citric acid cycle. Decarboxylation reactions remove carbon atoms as $\text{CO}_2$.

It allows NADH oxidation to regenerate NAD$^+$ via the ETC. NAD$^+$ must be regenerated to continue the glycolytic pathway.

Regenerate NAD$^+$ so glycolysis can continue. NADH is oxidized back to NAD$^+$ without oxygen present.

Cytosol. Glycolysis occurs in the cell's cytoplasm, not in organelles.

Carbon dioxide ($CO_2$). Carbon atoms from acetyl groups are released as waste $CO_2$ gas.

ADP. ADP is the acceptor molecule that gets phosphorylated to form ATP.

$C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{ATP}$. Glucose is oxidized with oxygen to produce carbon dioxide, water, and energy as ATP.

NADH and FADH₂. These electron carriers feed into the ETC to generate most ATP.

Oxygen. Oxygen receives electrons at the end of the chain, forming water.

Catalyzes the formation of ATP. This enzyme uses proton gradient energy to phosphorylate ADP into ATP.

Electron carriers. These molecules transport electrons from metabolic reactions to the ETC.

ADP. ADP is the acceptor molecule that gets phosphorylated to form ATP.

Carbon dioxide ($CO_2$). Carbon atoms from acetyl groups are released as waste $CO_2$ gas.

Cytoplasm. Glycolysis occurs outside the mitochondria in the cell's main compartment.

2 ATP molecules. Two turns of the cycle produce 2 ATP through substrate-level phosphorylation.

Glycolysis. The initial breakdown of glucose occurs in the cytoplasm without oxygen.

Glycolysis. Only glycolysis can proceed without oxygen, unlike the other stages.

Approximately 38 ATP molecules. Maximum theoretical yield from complete glucose oxidation through all stages.

ATP. Universal energy molecule that powers most cellular processes.

Krebs cycle (Citric Acid Cycle). Acetyl-CoA is oxidized to produce electron carriers and ATP.

Mitochondrial matrix. The innermost compartment of mitochondria where the cycle enzymes are located.

NAD⁺ or FAD. These molecules accept and transport electrons during metabolic oxidation.

Approximately 34 ATP molecules. Electron flow creates proton gradient that drives ATP synthase production.

Transfers acetyl group to the Krebs cycle. Carries acetyl groups from pyruvate oxidation into the Krebs cycle.

Inner mitochondrial membrane. Embedded in the cristae where proton pumping and ATP synthesis occur.

Net gain of 2 ATP molecules. 4 ATP are made but 2 are consumed, yielding a net gain of 2 ATP.

Direct ATP synthesis from a substrate in glycolysis/Krebs cycle. Direct transfer of phosphate from substrate to ADP without electron transport.