Chapter 21 proton movement force

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How is the proton gradient generated?

• Electrons move through ETC

• Protons get pumped out of the matrix

• Creates a gradient

• Protons flow back to create ATP

What are charge and chemical gradients?

Difference in electrical charge and concentration of molecules

What is F0?

Forms a channel for protons to flow back into the matrix

• located: on inner mitochondrial membrane

What is F1?

Responsible for synthesizing ATP and ADP and phosphate

• located: Sticks out on mitochondrial matrix

How does proton flow through the synthase produce rotation?

• Protons flow through F0, causing rotation

• The rotation moves F1 changing its shape

• the shape change help makes ATP from ADP and phosphate

Which subunits rotate in F0/F1?

C subunits in F0, and y subunits in F1 move with them

Which subunits are stationary?

A subunit in F0, and alpha and beta in F0

What subunit is ATP formed?

Beta

How does rotation affect ATP formation?

As y rotates in induces conformational changes

• Open (O)

• Loose (L)

• Tight (T)

What does Open (O) mean?

Beta subunit can bind or release nucleotides

What does Loose (L) mean?

Beta subunit can bind ADP and inorganic Pi but does not release them

What does Tight (T) mean?

Beta subunit strongly binds to ADP and Pi, facilitating the conversion into ATP

How many ATP are yield from a glucose molecule being produced by the synthase?

26 ATP

• 2 are produced via Glycolysis

• 2 are produced via TCA

• 30 total

What shuttle systems allow for the use of cytoplasmic NADH?

• Glycerol 3-phosphate shuttle

  • used in muscle, transfers electrons from NADH and FADH2 which enters the ETC and produces less ATP

• Malate-Aspartate Shuttle

  • Used in heart/liver, transfers electrons from cytoplasmic NADH to generate mitochondrial ATP w/o bypassing complex I

What is the energy cost of using the glycerol 3-phosphate shuttle?

Less ATP compared to mitochondrial NADH

• Converts NADH to FADH2, entering at complex II

• Yield 1.5 ATP per FADH2

  • mitochondrial NADH produces 2.5 ATP

What is ATP-ADP translocase?

It exports ATP to the cytoplasm and imports ADP to the mitochondria

• protein in the mitochondrial membrane

• essential for maintaining energy balance and supporting ATP synthesis during oxidative phosphorylation

• ATP out ADP in

What are the consequences for oxidative phosphorylation of inhibiting the ETC?

• Decreased ATP production

• Increased NADH and FADH2 levels

• Decreased O2 consumption

• Increased ROS production

• Altered metabolism

• Cellular dysfunction/death

What is uncoupling?

Disruption of coupling between between the ETC and ATP synthesis

• protons leak across the membrane bypassing ATP synthase

What is uncoupling’s effect on ATP production?

Decreases it due to decrease efficiency