Problem 9 What is meant by the ATP currenc... [FREE SOLUTION]

Chapter 11: Problem 9

What is meant by the ATP currency exchange ratio? Why does the oxidation of mitochondrial FADH \(_{2}\) generate one less ATP than oxidation of mitochondrial NADH?

Short Answer

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Question: Explain why the oxidation of mitochondrial FADH鈧� generates one less ATP than NADH. Answer: The oxidation of mitochondrial FADH鈧� generates one less ATP than NADH because FADH鈧� enters the electron transport chain (ETC) at Complex II, bypassing Complex I. This causes fewer protons to be pumped into the intermembrane space, resulting in a smaller proton gradient. Consequently, fewer protons are available for ATP synthesis through ATP synthase, making FADH鈧� generate one less ATP than NADH during oxidative phosphorylation.

Step by step solution

Defining ATP currency exchange ratio

The ATP currency exchange ratio refers to the number of ATP (adenosine triphosphate) molecules generated or consumed during a biological reaction. This ratio reflects the energy changes during the reaction under study, whether it is energy generation, storage, or consumption. ATP is the primary molecule responsible for energy storage and transport within cells.

Understanding oxidation of mitochondrial FADH鈧� and NADH

NADH (Nicotinamide adenine dinucleotide) and FADH鈧� (Flavin adenine dinucleotide) are two important molecules that carry electrons during cellular respiration. The main goal during cellular respiration is to generate ATP, the cell's energy currency, from the breakdown of glucose or other substrates. Both NADH and FADH鈧� transfer their electrons to the electron transport chain (ETC) within the mitochondria, and this electron flow transports protons across the inner mitochondrial membrane, creating a proton gradient. Proton gradients are then utilized by ATP synthase, directly involved in the production of ATP.

Comparing the oxidation of mitochondrial FADH鈧� and NADH

The key difference between FADH鈧� and NADH is that NADH enters the ETC at a higher energy level (Complex I) than FADH鈧� (Complex II). This means that FADH鈧� contributes fewer protons to the proton gradient compared to NADH. Thus, the oxidation of mitochondrial FADH鈧� generates one less ATP than NADH. While the oxidation of NADH generates approximately 2.5 to 3 ATP per molecule, the oxidation of FADH鈧� generates around 1.5 to 2 ATP.

Why FADH鈧� generates one less ATP

Due to FADH鈧� entering the ETC at Complex II, it bypasses Complex I (also known as NADH dehydrogenase). Thus, FADH鈧� skips the first site of proton pumping out of the mitochondrial matrix, resulting in fewer protons being pumped into the intermembrane space. Because of this, the proton gradient generated from the oxidation of FADH鈧� is smaller, and fewer protons are available for ATP synthesis through ATP synthase. This is the reason why FADH鈧� generates one less ATP than NADH during oxidative phosphorylation.

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91影视

What is meant by the ATP currency exchange ratio? Why does the oxidation of mitochondrial FADH \(_{2}\) generate one less ATP than oxidation of mitochondrial NADH?

Short Answer

Step by step solution

Defining ATP currency exchange ratio

Understanding oxidation of mitochondrial FADH鈧� and NADH

Comparing the oxidation of mitochondrial FADH鈧� and NADH

Why FADH鈧� generates one less ATP

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