Cellular Respiration

Vocabulary flashcards covering the key terms, stages, and molecules involved in aerobic and anaerobic cellular respiration.

Aerobic Respiration

Metabolic processes that require oxygen to produce ATP, occurring mostly in the mitochondria and producing $36$ to $38$ molecules of ATP per $1\,\text{mol}$ of glucose.

Anaerobic Respiration

Metabolic processes that require no oxygen to produce energy, occurring in the cytoplasm and producing $2$ molecules of ATP per $1\,\text{mol}$ of glucose.

Glycolysis

An enzyme-assisted anaerobic process occurring in the cytoplasm wherein a molecule of glucose is broken down into $2$ molecules of pyruvic acid, yielding a net gain of $2$ ATP molecules.

Krebs Cycle

A series of energy-extracting chemical reactions occurring inside the matrix of the mitochondrion in the presence of oxygen, wherein pyruvic acid is broken down into carbon dioxide.

Electron Transport Chain (ETC)

The final stage of aerobic cellular respiration consisting of a series of oxidized carrier proteins in the inner mitochondrial membrane that pass high-energy electrons in exergonic redox reactions.

Acetyl-CoA

A compound that adds a $2\text{-carbon}$ acetyl group to a $4\text{-carbon}$ molecule to form a $6\text{-carbon}$ molecule called citric acid at the start of the Krebs cycle.

Citric Acid

A $6\text{-carbon}$ molecule formed during the Krebs cycle when Acetyl-CoA combines its acetyl group with a $4\text{-carbon}$ molecule.

Oxaloacetic Acid

A $4\text{-carbon}$ molecule in the Krebs cycle produced from the breakdown of citric acid, which picks up another acetyl group to restart the cycle.

$$NAD^+$$

An electron acceptor that collects hydrogen atoms as glucose is broken down, forming the electron carrier $NADH$.

$$FADH_2$$

Flavin adenine dinucleotide, an energy carrier molecule produced during the Krebs cycle alongside $NADH$ and ATP.

Oxygen

The final electron acceptor of the electron transport chain that combines with low-energy electrons and hydrogen ions ($H^+$) to form water.

Fermentation

The process of releasing energy from a glucose molecule in the absence of oxygen by passing high-energy electrons from $NADH$ back to pyruvic acid to regenerate $NAD^+$.

Alcoholic Fermentation

A type of anaerobic respiration in organisms like yeast where a $3\text{-carbon}$ pyruvate is broken down into ethyl alcohol (ethanol) and $CO_2$.

Lactic Acid Fermentation

A type of anaerobic respiration where pyruvic acid is directly reduced to a $3\text{-carbon}$ lactate (lactic acid) without releasing $CO_2$, regenerating $NAD^+$.