Cellular Respiration: Pathways and Processes Section 2, 3, and 4: Glycolysis, Pyruvate Oxidation & Entry to Citric Acid Cycle, and Citric Acid Cycle (Krebs Cycle)

Glycolysis

First step of cellular respiration in cytoplasm, converting glucose to pyruvate and producing ATP.

NAD+

Coenzyme acting as an electron carrier in respiration.

Hydrogen Atom Transfer

Process of moving hydrogen atoms during oxidation.

Substrate-Level Phosphorylation

Direct ATP production occurs from organic substrates without electron transport involvement.

Energy investment phase

Initial ATP usage during glycolysis.

Energy payoff phase

Energy payoff phase: ATP production phase in glycolysis.

Net yield of glycolysis

2 ATP and 2 NADH per glucose.

Glucose

Primary energy source oxidized during respiration.

Shuttle Systems

Transport mechanisms for NADH into mitochondria.

Polysaccharides

Complex carbohydrates hydrolyzed to glucose for energy.

Amino Acids

Building blocks of proteins, can enter respiration pathways.

Anabolic Pathways

Synthesize molecules, consuming ATP instead of generating.

Pyruvate

End product of glycolysis, converted to acetyl CoA.

The Link & Product of Acetyl CoA

A 2-carbon molecule with a coenzyme A attached, formed from pyruvate and serving as the primary fuel that enters the citric acid cycle.

Dehydrogenase Enzymes

Enzymes that remove hydrogen atoms (and electrons) from pyruvate during its conversion to Acetyl CoA.

Mitochondrial Matrix (location):

The specific compartment within the mitochondrion where pyruvate oxidation takes place.

Carbon dioxide (CO2)

One carbon atom from pyruvate is released as carbon dioxide during this transition step

NADH (produced from pyruvate):

NAD+ is reduced to NADH, capturing energy from oxidizing pyruvate.

The stage of Pyruvate

The 3-carbon molecule produced by glycolysis that enters the mitochondrion for the next stage.

High energy of Acetyl CoA

This thioester bond in Acetyl CoA stores significant potential energy that will be harnessed in the subsequent steps of respiration.

Citric Acid Cycle

Second step of cellular respiration oxidizes acetyl CoA, producing ATP and carriers.

Krebs cycle

Another name for the citric acid cycle.

Oxaloacetate

Four-carbon molecule combining with acetyl CoA.

Citrate

Six-carbon compound formed in the citric acid cycle.

FADH2

Reduced FAD is an electron carrier transporting electrons.

Acetyl CoA

Pyruvate oxidation produces high-energy compound for citric acid cycle.

Mitochondrion

Organelle where aerobic respiration occurs (site of the citric acid cycle in eukaryotes).

Enzyme

Catalyst speeding up biochemical reactions (many enzymes involved in the cycle).

Chemical energy

Energy stored in molecular bonds (transformed during the cycle).

Active transport

Energy-dependent movement of molecules across membranes (relevant for moving molecules in/out of mitochondria for the cycle).

High potential energy

Energy-rich state of acetyl CoA (entering the cycle).

Oxidation

Loss of electrons from a substance.