Electron Transport Chain Overview

A series of protein complexes embedded in the inner mitochondrial membrane that transfer electrons and release energy, driving the production of ATP.

The ETC generates a proton gradient across the inner mitochondrial membrane, moving protons from the matrix to the intermembrane space. This gradient represents potential energy that is used to drive ATP synthesis.

The process by which ATP is synthesized using the energy released from the electron transport chain. This process couples the movement of protons across the membrane to the phosphorylation of ADP.

A protein complex in the inner mitochondrial membrane that uses the proton gradient established by the ETC to synthesize ATP from ADP and inorganic phosphate.

In eukaryotes, protons are pumped from the mitochondrial matrix into the intermembrane space, creating a gradient. In prokaryotes, protons are pumped across the plasma membrane, creating a gradient.

Ubiquinone (Q), also known as coenzyme Q, is a small, mobile electron carrier that shuttles electrons between Complexes I and II to Complex III within the electron transport chain.

Cytochrome c (cyt c) is a small, water-soluble protein that ferries electrons between Complex III and Complex IV in the ETC.

The proton gradient created by the ETC across the mitochondrial membrane is called the proton motive force (PMF). Its energy is harnessed by ATP synthase to produce ATP.

ATP synthase utilizes the proton motive force to drive oxidative phosphorylation, catalyzing the synthesis of ATP from ADP and Pi.

In prokaryotes, the ETC is located in the plasma membrane, and the proton gradient forms across this membrane. In eukaryotes, ETC occurs in the inner mitochondrial membrane, and the proton gradient spans this membrane.

The potential energy within molecules is determined by the distance of electrons from the atomic nucleus. Non-polar bonds have more distributed electrons, while polar bonds have concentrated electrons.

A redox reaction involves the transfer of electrons between molecules. The molecule that gains electrons is reduced, while the molecule that loses electrons is oxidized.

Redox reactions can release energy when high energy electrons are transferred to lower energy states. This energy can then be captured and utilized by the cell. Think of the process like a waterfall: high energy water (electrons) is released and converted into something useful.

Cellular respiration cannot capture all the energy from burning glucose due to the limitations of redox reactions. Not all energy can be harnessed, and some is lost as heat. This is analogous to burning a log: it produces heat and light, but you can't capture all the energy from the fire.

Electron carriers, like NAD+ and FAD, act as shuttle molecules that accept and transfer electrons. They exist in two forms: oxidized (NAD+, FAD) and reduced (NADH, FADH2). Think of them as mobile fuel tanks: they carry energy-rich electrons.

Cellular respiration uses electron carriers and a series of redox reactions for efficient energy harvesting. Multiple steps ensure gradual release of energy, allowing the cell to capture it effectively. Think of it as a multi-stage rocket launch: each stage burns fuel and releases energy, ultimately leading to launch.

Glycolysis occurs in the cytoplasm and converts glucose into pyruvate, producing ATP and NADH. Think of it as the first stage of breaking down sugar.

The citric acid cycle, also known as the Krebs cycle, takes place in the mitochondrial matrix and generates ATP, NADH, and FADH2 from acetyl-CoA. Think of it as the engine that fuels the cell.