Electron Transport Chain (ETC)

Question 1

ETC

Answer 1

Series of protein complexes in inner mitochondrial membrane (each mitochondria has many ETCs) –> complexes in order of increasing electronegativity (increasing attraction to electrons)

Question 1

Process

Answer 1

1. NADH gets reduced into NAD+ by NADH dehydrogenase complex, which uses energy from electrons to pump one H+ into intermembrane space
2. Electrons passed onto carrier Q, FADH2 gets reduced into FAD by Q; all electrons get passed to cytochrome b-c1 complex
3. Complex uses energy from electrons to pump another H+ into intermembrane space from matrix then passes electrons to carrier cyt C
4. Cyt C passes to cytochrome C oxidase complex which uses energy to pump final H+ ion into space from matrix
5. Electrons go to oxygen below complex and combine with oxygen + H+ to produce water

Question 2

Chemosmosis and Oxidative Phosphorylation

Answer 2

H+ reservoir in intermembrane space creates electrochemical gradient (charge difference) which stores free energy called proton-motive force (PMF); causes H+ to go through ATP synthase across membrane (since membrane impermeable to H+ ions) which powers synthesis of ATP from ADP + Pi –> ATP transported through mitochondrial membrane into cytoplasm through facilitated diffusion

Question 3

ATP Count in ETC

Answer 3

Inner membrane impermeable to NADH, so 2 NADH made in cytoplasm must be transported using transport proteins (channels), converting to FADH2 in process
1 ATP per 1 H+ pumped –> 1 NADH = 3 ATP, 1 FADH2 = 2 ATP

Question 4

Application

Answer 4

In order for ATP to be produced, H+ reservoir must be maintained, so electrons must continuously move, so food needed –> to keep electrons moving: oxygen must be at end of chain (most electronegative), otherwise:
- Electrons clog up, no H+ reservoir, no ATP synthesis, no recycling of carriers, death

Question 5

ATP Tally

Answer 5

Substrate level + oxidative with NADH + oxidative with FADH2 = 4 + 24 + 8 = 36