Reakcja pomostowa and Cykl Krebsa

The second stage of oddychanie tlenowe is the reakcja pomostowa, which occurs in the mitochondrial matrix. This stage links glikoliza to the Krebs cycle.

Definition: Reakcja pomostowa is the process that converts pyruvate into acetyl-CoA, which then enters the Krebs cycle.

The reaction involves three main steps:

1. Decarboxylation - removal of CO2
2. Oxidation - removal of hydrogen atoms and reduction of NAD+ to NADH + H+
3. Attachment to Coenzyme A

The balance of the reaction is: 2 Pyruvate + 2NAD+ + 2CoA → 2 Acetyl-CoA + 2NADH + 2H+ + 2CO2

Highlight: The reakcja pomostowa occurs twice for each glucose molecule, as glikoliza produces two pyruvate molecules.

The third stage is the cykl Krebsa, also known as the citric acid cycle or tricarboxylic acid cycle. It takes place in the mitochondrial matrix and involves a series of reactions that complete the oxidation of glucose.

Key points of the Krebs cycle include:

• Two decarboxylation steps, releasing 2CO2
• Four oxidation steps, removing hydrogen atoms
• Production of 6 NADH + H+, 2 FADH2, and 2 ATP molecules per glucose molecule

Example: The Krebs cycle is like a cellular "energy factory," where the acetyl-CoA from the reakcja pomostowa is fully oxidized to produce energy-rich molecules like NADH and FADH2.

The final stage, fosforylacja oksydacyjna, occurs in the inner mitochondrial membrane. It involves the electron transport chain and ATP synthase, which use the energy from NADH and FADH2 to produce the majority of ATP in cellular respiration.

Vocabulary: Fosforylacja oksydacyjna is the process where electrons from NADH and FADH2 are passed through the electron transport chain, creating a proton gradient that drives ATP synthesis.

In total, the process of oddychanie tlenowe produces approximately 30-32 ATP molecules per glucose molecule, making it a highly efficient energy production system in cells.