electron transport + chemiosmosis

What does NADH and FADH2 do? What happens to them there?

carry electrons to E.T.C

• each become oxidized, losing TWO electrons to the ETC and releasing H+ ions to the matrix

The inner mitochondrial membrane is __ to H+ ions. How do they pass? What does this create?

The inner mitochondrial membrane is IMPERMEABLE to H⁺ ions

How:

• protein complexes embedded in the inner membrane use the energy from the electrons to actively transport, or pump hydrogen ions (H+) out of the matrix and into the intermembrane space

Creates: pumping H+ ions out of the matrix and into the intermembrane space creates an electrochemical gradient

What is an electrochemical gradient? What does it mean for the H+ ions?

Electrochemical gradient:

• Chemical gradient = difference in H⁺ concentration.

• Electrical gradient = difference in electrical charge.

Meaning:

• higher positive charge (H+) ions in the intermembrane space than in the matrix

• Higher concentration of H+ ions in the intermembrane space than in the matrix

What is the PMF?

Proton movement force

• in the intermembrane space H+ ions desire to MOVE AWAY from each other because they REPEL one another (like charges) AND THEY WANT TODIFFUSE INTO THE MATRIX (low H+ concentration)

• causes H+ ions to move around (KINETIC ENERGY) in the intermembrane space

How does ATP generation happen?

• because H+ are unable to move through the inner membrane because it is impermeable for them, H+ ions are forced to move through special protein channels called ATP SYNTHASE

• free energy of the electrochemical gradient drives the synthesis of ATP from ADP and Pi in the matrix; CHEMIOSMOSIS

What is chemiosmosis? What are the 3 steps?

what: Chemiosmosis is the process where H⁺ ions (protons) flow down their concentration gradient through ATP synthase, providing the energy needed to make ATP.

Step 1: Build up the H⁺ gradient

• The ETC uses energy from electrons to pump H⁺ ions from the matrix into the intermembrane space.

• This creates a higher H⁺ concentration in the intermembrane space.

Step 2: H⁺ flows back into the matrix

• The inner mitochondrial membrane is impermeable to H⁺.

• Therefore, H⁺ cannot freely cross the membrane.

• H⁺ must pass through a protein called ATP synthase.

Step 3: ATP is produced

• As H⁺ flows through ATP synthase, it provides energy.

• ATP synthase uses this energy to combine ADP + Pi (inorganic phosphate) to produce ATP.

What happens to the NADH from glycolysis?

GLYCEROL PHOSPHATE SHUTTLE SYSTEM

• process that transfers the high-energy electrons from NADH in the cytoplasm into the mitochondria so they can enter the electron transport chain (ETC).

**NADH itself cannot cross the inner mitochondrial membrane, so the cell needs a shuttle system to transfer its electrons.

What causes H+ to move?

• likes repel + more collisions

Where is the ETC located?

inner mitochondrial membrane, specifically along the folds called the cristae.