RESPIRASI AEROB : DEKARBOKSILASI OKSIDATIF

Summary

This script discusses the second stage of aerobic respiration, the oxidative decarboxylation of pyruvate. It explains that less than a quarter of the chemical energy from glucose is released in this stage, with most energy remaining in pyruvate molecules. In eukaryotic cells, pyruvate enters mitochondria for further reactions, while prokaryotic cells lack mitochondria and undergo reactions directly in the cytoplasm. The script outlines three main reactions: decarboxylation of pyruvate to release carbon dioxide, oxidation of the remaining two-carbon fragment to form acetate, and the transfer of electrons to form NADH and acetyl-CoA, which enters the Krebs cycle for further oxidation.

Takeaways

• 🌀 The second stage of aerobic respiration is oxidative decarboxylation.
• 🔋 This stage releases less than a quarter of the chemical energy stored in glucose.
• 🌐 Most of the energy remains trapped within the two molecules of pyruvate.
• 🌿 In the presence of oxygen, pyruvate molecules enter mitochondria in eukaryotic cells.
• 🦠 Prokaryotic cells lack mitochondria, so pyruvate undergoes reactions directly in the cytoplasm.
• 🚀 Pyruvate enters the mitochondria through active transport, requiring energy.
• 🔬 There are three main reactions in oxidative decarboxylation: decarboxylation, oxidation, and transfer of electrons.
• 🍃 Decarboxylation involves the removal of a carboxyl group from pyruvate, releasing carbon dioxide.
• 🔄 The remaining two-carbon fragment is oxidized to form acetate.
• 🔋 Electrons are transferred to NAD+, forming NADH.
• 🔄 Coenzyme A, derived from vitamin B, combines with acetate to form acetyl-CoA, a high-energy compound.
• ♻️ Acetyl-CoA then enters the Krebs cycle for further oxidation.

Q & A

What is the second stage of aerobic respiration called?

The second stage of aerobic respiration is called oxidative decarboxylation.

Where does pyruvate enter during oxidative decarboxylation in eukaryotic cells?

In eukaryotic cells, pyruvate enters the mitochondria during oxidative decarboxylation.

What happens to pyruvate in prokaryotic cells since they lack mitochondria?

In prokaryotic cells, pyruvate directly undergoes the next reaction in the cytosol because they lack mitochondria.

What type of transport is required for pyruvate to enter the mitochondria?

Active transport is required for pyruvate to enter the mitochondria from the cytoplasm, which requires energy.

What is the first major reaction in oxidative decarboxylation?

The first major reaction is the removal of the carboxyl group from pyruvate, which is released as carbon dioxide.

Why is this stage referred to as decarboxylation?

This stage is called decarboxylation because it involves the release of the carboxyl group from pyruvate as carbon dioxide.

What is formed after the removal of the carboxyl group from pyruvate?

After the carboxyl group is removed, a two-carbon fragment remains, which is oxidized to form acetate.

What happens to the electrons extracted during the oxidation of the two-carbon fragment?

The electrons extracted during the oxidation are transferred to NAD+, forming NADH.

What is the role of coenzyme A (CoA) in oxidative decarboxylation?

Coenzyme A (CoA), a sulfur-containing compound derived from vitamin B, binds to acetate, forming acetyl-CoA, which has high potential energy.

What products are generated at the end of oxidative decarboxylation for two pyruvate molecules?

The products generated are two molecules of carbon dioxide, two molecules of NADH, and two molecules of acetyl-CoA.