A2 Biology - Glucose to ATP: Calculation

Summary

This video script explains the complex biochemical processes of cellular respiration, focusing on how ATP is generated from a single glucose molecule. It covers the stages of glycolysis, the link reaction, and the Krebs cycle, detailing how each process contributes to ATP production. The script emphasizes the production of NADH and FADH2 and how they contribute to further ATP generation via the electron transport chain. In total, 38 ATP molecules are produced from one glucose molecule, with a net gain of 38 ATP after accounting for initial losses. The video serves as a clear overview of the key stages in cellular energy production.

Takeaways

• 😀 Glycolysis is the first step in breaking down glucose, resulting in 2 pyruvate molecules and a net gain of 2 ATP.
• 😀 During glycolysis, 2 reduced NADH molecules are produced, which play a key role in ATP production later.
• 😀 The link reaction takes place after glycolysis, where each pyruvate is converted into Acetyl-CoA, releasing 1 CO2 and producing 1 reduced NADH.
• 😀 The Krebs cycle follows the link reaction, and it produces 2 ATP molecules per glucose, 6 NADH, 2 FADH2, and 4 CO2.
• 😀 Reduced NADH from glycolysis, the link reaction, and Krebs cycle contribute significantly to ATP production, each yielding 3 ATP per NADH.
• 😀 Reduced FADH2, produced in the Krebs cycle, generates 2 ATP per FADH2 molecule.
• 😀 In total, the production of 2 reduced NADH from glycolysis leads to 6 ATP, and 6 NADH from the Krebs cycle contributes 18 ATP.
• 😀 The Krebs cycle also generates 2 FADH2 molecules, which contribute 4 ATP (2 ATP each).
• 😀 The overall ATP production from one glucose molecule is 38 ATP after considering the 2 ATP used in glycolysis.
• 😀 Understanding the processes of glycolysis, the link reaction, and the Krebs cycle is crucial for calculating the ATP yield from glucose breakdown.
• 😀 It’s important to remember that both pyruvate molecules from glycolysis enter the Krebs cycle, effectively doubling the ATP yield from the processes.

Q & A

What is the total ATP production from one glucose molecule after glycolysis?

The total ATP production from one glucose molecule in glycolysis is 2 ATP. This is a net gain, as 2 ATP are consumed in the process but 4 ATP are produced.

How many pyruvate molecules are produced during glycolysis?

Glycolysis produces two pyruvate molecules from one glucose molecule.

What happens to pyruvate after glycolysis?

After glycolysis, each pyruvate molecule enters the linking reaction (pyruvate decarboxylation) where it is converted into Acetyl-CoA.

How many ATP are produced in the linking reaction?

No direct ATP is produced in the linking reaction. However, it generates 2 NADH molecules (one for each pyruvate), which contribute to ATP production in later stages.

What is the main product of the Krebs cycle per pyruvate?

For each pyruvate, the Krebs cycle produces 1 ATP, 3 NADH, 1 FADH2, and 2 CO2 molecules.

How many ATP are generated from NADH and FADH2 produced in the Krebs cycle?

For each NADH produced, 3 ATP are generated, and for each FADH2, 2 ATP are generated, through the electron transport chain during oxidative phosphorylation.

How many total ATP are produced from the two pyruvates in the Krebs cycle?

From two pyruvates, the Krebs cycle produces 2 ATP, 6 NADH (which generates 18 ATP), and 2 FADH2 (which generates 4 ATP), totaling 24 ATP.

How is the total ATP production from glucose calculated?

The total ATP production from glucose is calculated by adding the ATP generated in glycolysis (2 ATP), the NADH from the linking reaction (6 ATP), and the ATP and NADH/FADH2 produced in the Krebs cycle (24 ATP). This gives a total of 38 ATP from one glucose molecule.

Why is the ATP count from NADH and FADH2 not constant?

The ATP count from NADH and FADH2 can vary slightly depending on the efficiency of the electron transport chain, but typically, 1 NADH yields 3 ATP, and 1 FADH2 yields 2 ATP.

What is the net ATP gain from one glucose molecule after considering all the processes?

The net ATP gain from one glucose molecule, after considering glycolysis, the linking reaction, and the Krebs cycle, is 38 ATP, accounting for the 2 ATP consumed in glycolysis.