Cellular Respiration: Pyruvate Oxidation and the Krebs Cycle Flashcards

Vocabulary terms and definitions focusing on the chemical processes, energy-rich molecules, and cofactors involved in pyruvate oxidation and the citric acid cycle.

Redox Reactions

Oxidation and reduction reactions used by cells to release and transfer energy from food molecules.

Oxidation

The loss of one or more electrons ($e^-$) and/or Hydrogen atoms ($H$) from a substance that reduces its energy content.

Reduction

The gain of one or more electrons and/or $H$ atoms by a substance that increases its energy content.

Pyruvate Oxidation

A catabolic process occurring in the mitochondrion matrix under aerobic conditions that produces Acetyl CoA, NADH, and one molecule of $CO_2$ from pyruvate.

Krebs Cycle (Citric Acid Cycle)

A sequence of eight enzymatic reactions in the mitochondrion matrix that releases energy from Acetyl CoA to produce $FADH_2$, GTP, NADH, and two $CO_2$ molecules.

Acetyl CoA (Acetyl Coenzyme A)

An energy-rich molecule produced by pyruvate oxidation that is catabolized by the Krebs cycle to make $FADH_2$, GTP, and NADH.

Oxaloacetate

A $4$-carbon molecule that combines with a $2$-C acetyl group to produce the $6$-carbon compound citrate.

Citrate

The $6$-carbon compound produced at the beginning of the citric acid cycle when Acetyl-CoA combines with oxaloacetate.

Vitamin B1 (Thiamine)

A precursor used to make Thiamine Pyrophosphate (TPP), an essential coenzyme for pyruvate oxidation.

Vitamin B2 (Riboflavin)

A precursor used to make the essential coenzyme FAD.

Vitamin B3 (Niacin)

A precursor used to make the essential coenzyme $NAD^+$.

Vitamin B5 (Pantothenic Acid)

A precursor used to make Coenzyme A (CoA).

NADH

An energy-rich molecule used to make ATP in mitochondria; one molecule yields approximately $2.5 - 3$ ATP molecules.

$$FADH_2$$

An energy-rich molecule used to make ATP in mitochondria; one molecule yields approximately $1.5 - 2$ ATP molecules.

GTP

An energy-rich molecule produced by the Krebs cycle that is converted to ATP by Nucleoside-Diphosphate Kinase.

Nucleoside-Diphosphate Kinase

An enzyme that converts $1$ GTP to $1$ ATP.

Mitochondrion Matrix

The location where pyruvate oxidation and the Krebs cycle occur.

Inner Membrane

The location within the mitochondrion where the electron transport chain (ETC) is found.

Amphibolic

A term describing the Krebs cycle because it involves both anabolic processes (making amino acids, lipids, etc.) and catabolic processes.

$CO_2$ (Carbon Dioxide)

A catabolic waste product of pyruvate oxidation (one molecule) and the Krebs cycle (two molecules) that exits the body by exhalation.