The final stage of cellular respiration is oxidative phosphorylation, which consists of (1) an electron transport chain and (2) chemiosmosis.
The electron transport chain is a set of proteins and other organic molecules found in the inner membrane of mitochondria in eukaryotic cells and the plasma membrane of prokaryotic cells. The electron transport chain has two primary functions: it produces a proton gradient—storing energy that can be used to create ATP during chemiosmosis—and generates electron carriers, such as NAD+ and FAD, that are used in glycolysis and the citric acid cycle.
Generally, molecules of the electron transport chain are organized into four complexes (I-IV). The molecules pass electrons to one another through multiple redox reactions, moving electrons from higher to lower energy levels through the transport chain. These reactions release energy that the complexes use to pump H+ across the inner membrane (from the matrix into the intermembrane space). This forms a proton gradient across the inner membrane.
NADH and FADH2 are reduced electron carriers produced during earlier cellular respiration phases. NADH can directly input electrons into complex I, which uses the released energy to pump protons into the intermembrane space. FADH2 inputs electrons into complex II, the only complex that does not pump protons into the intermembrane space. Thus, FADH2 contributes less to the proton gradient than NADH. NADH and FADH2 are converted back into electron carriers NAD+ and FAD, respectively.
Both NADH and FADH2 transfer electrons to ubiquinone, a mobile electron carrier that passes the electrons to complex III. From there, the electrons are transferred to the mobile electron carrier cytochrome c (cyt c). Cyt c delivers the electrons to complex IV, which passes them to O2. Oxygen breaks apart, forming two oxygen atoms that each accept two protons to form water.
From Chapter 8:
Now Playing
8.6 : שרשראות העברת אלקטרונים
Cellular Respiration
96.1K Views
8.1 : מהי גליקוליזה?
Cellular Respiration
162.5K Views
8.2 : תהליכי גליקוליזה דורשי-אנרגיה
Cellular Respiration
162.4K Views
8.3 : תהליכי גליקוליזיה משחררי-אנרגיה
Cellular Respiration
138.0K Views
8.4 : חמצון פירובט
Cellular Respiration
157.5K Views
8.5 : מחזור החומצה הציטרית
Cellular Respiration
149.9K Views
8.7 : אוסמוזה כימית יונית
Cellular Respiration
96.2K Views
8.8 : נשאי אלקטרונים
Cellular Respiration
83.6K Views
8.9 : תסיסה
Cellular Respiration
112.7K Views
8.10 : קישרים תזונתיים
Cellular Respiration
49.6K Views
8.11 : מהי נשימה תאית?
Cellular Respiration
171.8K Views
8.12 : תוצרי מחזור החומצה הציטרית
Cellular Respiration
97.9K Views
8.13 : תוצאות הגליקוליזה
Cellular Respiration
98.2K Views
8.14 : ניצולת ATP
Cellular Respiration
68.2K Views
Copyright © 2025 MyJoVE Corporation. All rights reserved