Cellular Respiration: Pathways and Processes Section 5: Oxidative Phosphorylation (Electron Transport Chain & Chemiosmosis)

Oxidative Phosphorylation

ATP is produced via electron transport chain and chemiosmosis, powered by oxygen use.

Electron Transport Chain

Proteins transfer electrons in mitochondrial respiration, pumping H+ and producing ATP efficiently.

Chemiosmosis

ATP production through H+ gradient-driven synthesis process.

Mitochondria

Site of cellular respiration in eukaryotic cells (location of oxidative phosphorylation).

Prokaryotes

Organisms where respiration occurs in plasma membrane (location in prokaryotes).

Inner Membrane

Location of electron transport and chemiosmosis in mitochondria.

Oxygen

Final electron acceptor in the electron transport chain.

ATP Yield

Almost 90% of ATP generated by oxidative phosphorylation.

Energy Release

Occurs in steps to prevent explosive reactions (in the ETC).

ATP

Energy currency of the cell, 7.3 kcal/mol (produced by oxidative phosphorylation).

Mitochondrial membrane

Membrane site for ATP synthesis and electron transport, utilizing chemiosmosis for energy production.

Proton-Motive Force

Proton gradient drives ATP synthesis in mitochondria for energy production.

Cristae

Folds of the inner mitochondrial membrane (increasing surface area for ETC).

Prosthetic groups

Nonprotein components essential for enzyme function (in ETC proteins).

Redox reactions

Electron transfer processes involving oxidation and reduction (driving the ETC).

Ubiquinone

Mobile electron carrier in the membrane (ETC).

Cytochromes

Proteins in electron transport with heme groups (ETC).

Cyt a3

Last cytochrome transferring electrons to oxygen (ETC).

Free energy drop

Electrons lose energy moving through the chain (ETC).

ATP synthesis

synthesizes ATP from ADP using a proton gradient.

Hydrogen ions

Protons involved in forming water from oxygen (at the end of ETC).

Energy yield

Total ATP from glucose is 38 ATP (majority from oxidative phosphorylation).

Electron carriers

Molecules that transfer electrons in respiration (NADH, FADH2, and within the ETC).

Lower energy level

FADH2 enters electron transport at a lower state (than NADH).

Hydrophobic molecule

Ubiquinone's property allows mobility in membranes (ETC).

Oxidized form

State of a molecule after losing electrons (in the ETC).

Ion Pump

Transports ions against gradients using ATP (conceptually related to proton pumps).

Polypeptides

Protein subunits making up ATP synthase structure.

Nutrient Pumping

Prokaryotic use of H+ gradients for nutrient transport (related concept).

Flagella Rotation

Movement mechanism powered by proton-motive force (related concept in prokaryotes).

H+ Diffusion

Movement of protons down their concentration gradient (through ATP synthase)

Intermembrane Space

Area where H+ accumulates during electron transport.

Mitochondrial Matrix

Space inside mitochondria where ATP synthesis occurs (where ADP and Pi are).

Efficiency of Respiration

Calculated as 34% for energy conversion, significantly influenced by oxidative phosphorylation processes.

Heat Loss

Energy not converted to ATP, released as heat (some occurs in ETC).

Brown Fat

Tissue generating heat without ATP during hibernation (involves uncoupling in mitochondria).

Uncoupling Protein

Allows protons to flow, generating heat instead of ATP (in mitochondria)

ATP Yield Variation

Depends on electron shuttle type used in cells (affecting NADH entry to ETC).

Body Temperature Maintenance

Heat generated helps maintain 37°C internal temperature (related to metabolic heat).

Substrate-Level Phosphorylation

Direct ATP production from a substrate without electron transport (contrasting with oxidative phosphorylation).

NADH

Reduced form of NAD+, carries electrons to electron transport.

Proton Gradient

Difference in H+ concentration across membranes (driving chemiosmosis).

Exergonic Reactions

Reactions releasing energy, driving H+ pumping (in the ETC).

ADP

Adenosine diphosphate, precursor to ATP.

Inorganic Phosphate

 Phosphate used in ATP synthesis with ADP.

Rotary Motor

ATP synthase's mechanism for ATP production.

H+ Channels

Specific pathways for protons to re-enter mitochondria (through ATP synthase).

Binding Sites

Locations on ATP synthase for H+ entry.

Osmosis

Flow of H+ across a membrane driving ATP synthesis (though "chemiosmosis" is the specific term).