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Zorluk: OrtaGaseous Exchange and Cellular Respiration

During aerobic respiration in eukaryotic mitochondria, oxidative phosphorylation generates the majority of cellular ATP via chemiosmosis. Which of the following represents the correct sequential order of these physiological events, from initial electron donation to the final synthesis of ATP?

  1. 1NADH and FADH2\text{FADH}_2 donate high-energy electrons to electron transport chain complexes embedded in the inner mitochondrial membrane.
  2. 2Electrons pass through a series of cytochromes, releasing energy used to actively pump protons (H+\text{H}^+) from the matrix into the intermembrane space.
  3. 3Protons accumulate in the intermembrane space, establishing a steep electrochemical proton gradient across the inner mitochondrial membrane.
  4. 4Protons flow passively down their electrochemical gradient back into the mitochondrial matrix through the ATP synthase complex.
  5. 5The rotation of ATP synthase catalyzes the chemical phosphorylation of ADP and inorganic phosphate to produce ATP.

Cevap

The correct sequence of oxidative phosphorylation events is: initial electron donation by NADH and FADH2\text{FADH}_2 to membrane complexes, active pumping of protons into the intermembrane space during electron transport, establishment of an electrochemical proton gradient, passive proton flow back into the matrix via ATP synthase, and finally the phosphorylation of ADP to yield ATP.
Oxidative phosphorylation begins with NADH and FADH2\text{FADH}_2 donating electrons to the transport chain in the inner mitochondrial membrane. Energy released during electron movement down the cytochromes actively pumps protons from the matrix into the intermembrane space, establishing an electrochemical proton gradient. Protons then re-enter the matrix passively through ATP synthase, driving the enzymatic phosphorylation of ADP to produce ATP.

Adım Adım Çözüm

1
Identify the starting substrates and entry point of high-energy electrons.
NADH and FADH2\text{FADH}_2 transfer electrons to electron transport chain complexes on the inner mitochondrial membrane.
Electrons must enter the respiratory chain to initiate electron movement and subsequent energy transformations.
2
Trace the path of electron movement and energy coupling.
As electrons travel along cytochromes, released energy pumps protons (H+\text{H}^+) from the matrix into the intermembrane space.
Exergonic electron transport is directly coupled to endergonic proton translocation across the membrane.
3
Determine the resulting membrane state caused by continuous proton pumping.
A proton concentration and electrical potential difference (proton motive force) builds up in the intermembrane space.
Accumulation of ions in a confined compartment establishes a steep electrochemical gradient.
4
Identify how the accumulated potential energy is released.
Protons diffuse down their gradient back into the mitochondrial matrix through the channel of ATP synthase.
The lipid bilayer is impermeable to protons, making ATP synthase the sole pathway for proton return.
5
Identify the terminal biochemical reaction generating cellular energy currency.
ATP synthase uses the proton flow to phosphorylate ADP with inorganic phosphate (Pi\text{P}_i) to form ATP.
Chemiosmosis converts the potential energy of the proton gradient into chemical bond energy in ATP.

Anahtar Kavram

Oxidative Phosphorylation and Chemiosmotic Coupling
Tahmini Süre:1m 30s
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Konular

Gaseous Exchange and Cellular Respiration

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