Question

What reduced coenzymes provide the electrons for electron transport?

Short answer

NADH and FADH2 provide electrons for electron transport.

Step-by-step solution

Identify Key Players

First, identify which coenzymes are associated with electron transport. The two main coenzymes are NADH (Nicotinamide adenine dinucleotide) and FADH2 (Flavin adenine dinucleotide).

Understand the Role of Reducing Agents

Recognize that NADH and FADH2 are in their reduced forms, meaning they have gained electrons. These electrons are crucial for the electron transport chain (ETC) in cellular respiration.

Electron Transfer

In the ETC, NADH and FADH2 donate the electrons they have gained to the electron carriers within the mitochondrial membrane. These electrons pass through a series of proteins and generate a proton gradient used to produce ATP.

Conclusion

Thus, the reduced coenzymes NADH and FADH2 provide the electrons for the electron transport chain.

Key concepts

NADH

NADH stands for Nicotinamide Adenine Dinucleotide in its reduced form. It plays a key role in cellular respiration. When cells break down glucose, NADH is produced in the glycolysis and the Krebs cycle.
The main function of NADH is to carry electrons to the electron transport chain (ETC).
By donating electrons, NADH becomes oxidized to NAD+. This process is essential for generating a proton gradient in the mitochondria.
NADH contributes significantly to ATP production, making it crucial for energy metabolism.

FADH2

FADH2 stands for Flavin Adenine Dinucleotide in its reduced form. Similar to NADH, it is crucial for the electron transport chain in cellular respiration.
FADH2 is produced during the Krebs cycle. It carries electrons to the ETC and donates them, turning back into FAD.
While both NADH and FADH2 are important, FADH2 produces fewer ATP molecules compared to NADH because it donates electrons further down the ETC.
This difference results in a lower proton gradient and consequently less ATP production.

Cellular Respiration

Cellular respiration is the process cells use to convert glucose into ATP, the energy currency of the cell.
It consists of three main stages: Glycolysis, the Krebs cycle, and the Electron Transport Chain (ETC).
During glycolysis, glucose is broken down into two molecules of pyruvate, producing a small amount of ATP and NADH.
In the Krebs cycle, these pyruvate molecules undergo further breakdown, generating more NADH and FADH2.
Finally, in the ETC, the electrons from NADH and FADH2 travel through protein complexes in the mitochondrial membrane, ultimately leading to ATP production.

ATP Production

ATP, or Adenosine Triphosphate, is the primary energy carrier in cells.
The majority of ATP is produced during the Electron Transport Chain (ETC).
Electrons from NADH and FADH2 are transferred through proteins in the mitochondrial membrane.
This process generates a proton gradient, which drives ATP synthesis.
It is estimated that each molecule of NADH can produce 2.5 ATP, while FADH2 produces about 1.5 ATP.
Thus, ATP production is tightly linked to the function of NADH and FADH2 in cellular respiration.

Proton Gradient

The proton gradient is a crucial aspect of the Electron Transport Chain (ETC).
As electrons pass through the ETC, protons (H⁺ ions) are pumped from the mitochondrial matrix to the intermembrane space.
This creates a high concentration of protons outside the inner mitochondrial membrane compared to inside.
The gradient generates a potential energy difference, often referred to as the electrochemical gradient.
Protons flow back into the mitochondrial matrix through ATP synthase, a protein that synthesizes ATP using the energy from the proton movement.
Thus, the proton gradient is directly responsible for driving ATP production in cellular respiration.