Respiração Celular Aeróbia: Glicólise, Ciclo de Krebs e Fosforilação Oxidativa 🐵

Summary

This video explains cellular respiration, the process by which cells generate ATP from organic molecules. It covers three main stages: glycolysis, the Krebs cycle, and the respiratory chain. Glycolysis occurs in the cytosol and breaks down glucose into pyruvate, producing 2 ATP. The Krebs cycle, in the mitochondrial matrix, decarboxylates pyruvate to release CO2 and generate ATP, NADH, and FADH2. The respiratory chain in the mitochondria uses oxygen to produce water and generates 32-34 ATP. The entire process yields 36-38 ATP from one glucose molecule, with fatty acids and amino acids serving as alternative energy sources.

Takeaways

• 😀 Glycolysis is the first stage of cellular respiration and occurs in the cytosol without the need for oxygen.
• 😀 In glycolysis, one glucose molecule is broken down into two pyruvate molecules, generating 4 ATP but consuming 2 ATP.
• 😀 The Krebs cycle (citric acid cycle) occurs in the mitochondrial matrix, where pyruvate is converted into acetyl-CoA and citric acid is formed.
• 😀 During the Krebs cycle, carbon dioxide is released, and high-energy electron carriers (NADH, FADH2) are produced.
• 😀 The Krebs cycle generates 6 CO2, 8 NADH, 2 FADH2, and 2 ATP molecules for each glucose molecule.
• 😀 The respiratory chain, also known as oxidative phosphorylation, occurs in the mitochondrial inner membrane and uses oxygen to produce ATP.
• 😀 In the respiratory chain, electrons are transferred, and hydrogen ions are pumped out of the mitochondrial matrix, ultimately forming water with oxygen.
• 😀 The oxidative phosphorylation stage produces 32 to 34 ATP molecules from the energy released by electrons in the respiratory chain.
• 😀 The total ATP yield from one glucose molecule after complete cellular respiration ranges from 36 to 38 ATP.
• 😀 If glucose is not available, cells can use fatty acids and amino acids for energy production in cellular respiration.

Q & A

What is the primary purpose of cellular respiration?

The primary purpose of cellular respiration is to break down organic molecules, particularly glucose, to produce ATP, which serves as the energy source for cellular activities.

Where does glycolysis occur, and what is its significance in cellular respiration?

Glycolysis occurs in the cytosol and is significant because it is the first step in cellular respiration, where glucose is broken down into two pyruvate molecules, producing 2 ATP and 2 NADH molecules without the need for oxygen.

How does the Krebs cycle contribute to the production of ATP?

The Krebs cycle, occurring in the mitochondrial matrix, contributes to ATP production by decarboxylating pyruvate, releasing carbon dioxide, and forming NADH and FADH2, which are later used in the respiratory chain to generate ATP.

What is the role of NADH and FADH2 in cellular respiration?

NADH and FADH2 are electron carriers that play a crucial role in the respiratory chain (oxidative phosphorylation), where they donate electrons to produce ATP through the electron transport chain.

What happens in the respiratory chain, and how much ATP does it generate?

In the respiratory chain, electrons are transferred along the mitochondrial inner membrane, releasing energy that drives the production of ATP. This process generates 32 to 34 ATP molecules.

What is oxidative phosphorylation, and where does it occur?

Oxidative phosphorylation is a process in the mitochondrial inner membrane where ATP is synthesized using energy from electron transport and the dissociation of hydrogen atoms, forming water as a byproduct.

What are the end products of glycolysis, and how much ATP is produced?

The end products of glycolysis are two pyruvate molecules, two NADH molecules, and a net gain of 2 ATP molecules.

Why does the Krebs cycle also produce carbon dioxide and hydrogen?

The Krebs cycle produces carbon dioxide as a result of the decarboxylation of citric acid and releases hydrogen atoms, which are carried by NADH and FADH2 to the respiratory chain for further ATP production.

How does the body adapt to energy scarcity when glucose is unavailable?

When glucose is unavailable, the body can use fatty acids and amino acids as alternative energy sources, breaking them down to produce ATP through processes like beta-oxidation and gluconeogenesis.

What is the total ATP yield from one molecule of glucose in cellular respiration?

The total ATP yield from one glucose molecule in cellular respiration ranges from 36 to 38 ATP molecules, depending on the efficiency of the process and the type of cell involved.