Cellular Respiration: Pyruvate Oxidation and the Krebs Cycle

A set of vocabulary flashcards covering the biochemical processes of cellular respiration, specifically focusing on pyruvate oxidation, the Krebs cycle, and the role of coenzymes and vitamins.

Redox Reactions

Oxidation and reduction reactions used by cells to release and transfer energy from food molecules to energy-rich molecules like ATP, GTP, $FADH_2$, and NADH.

Oxidation

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

Reduction

The gain of one or more electrons ($e^-$) and/or H atoms by a substance, which increases its energy content.

Mitochondrion Matrix

The specific location within the mitochondrion where both Pyruvate Oxidation and the Krebs Cycle occur.

Pyruvate Oxidation

The process that catabolizes pyruvate produced in glycolysis to generate Acetyl CoA, NADH, and one molecule of $CO_2$ as a waste product.

Acetyl CoA

A 2-carbon energy-rich molecule produced by pyruvate oxidation that combines with oxaloacetate to enter the Krebs cycle.

Oxaloacetate

A 4-carbon molecule that combines with the 2-carbon acetyl group to produce citrate; it is regenerated at the end of the Krebs cycle.

Citrate

A 6-carbon compound produced when a 2-carbon acetyl group combines with 4-carbon oxaloacetate at the start of the citric acid cycle.

Krebs Cycle (Citric Acid Cycle)

A sequence of eight enzymatic reactions that releases energy from Acetyl CoA to produce energy-rich $FADH_2$, GTP, and NADH molecules.

Carbon Dioxide ($CO_2$)

A metabolic waste product generated during pyruvate oxidation (one molecule) and the Krebs cycle (two molecules) that exits the body via exhalation.

Vitamin B1 (Thiamine)

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

Vitamin B2 (Riboflavin)

A precursor used to make the coenzyme FAD.

Vitamin B3 (Niacin)

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

Vitamin B5 (Pantothenic Acid)

A precursor used to make Coenzyme A (CoA).

Nucleoside-Diphosphate Kinase

The enzyme responsible for converting 1 GTP produced in the Krebs cycle into 1 ATP.

ATP Yield: NADH

One NADH molecule equates to approximately $2.5 - 3$ ATP molecules.

ATP Yield: $FADH_2$

One $FADH_2$ molecule equates to approximately $1.5 - 2$ ATP molecules.

Amphibolic

A term describing the Krebs cycle because it involves both catabolic and anabolic processes, such as using substrates to make amino acids or lipids.