Yes or No?

Does mitochondria have an inner membrane? What does it do?

What is in between the inner, and the outer membranes of the mitochondria?

the inner membrane is elaborately folded with shelflike cristae projecting into the matrix.

True or False?

Mitochondria has a small number (some 5–10) of  circular molecules of DNA?

True OR False? 

The number of mitochondria in a cell can change.

TRUE! they can increase by their fission (following mitosis) and decrease by fusing together.

[defects in either process can lead to very serious, even deadly, illness.]

What is in the Matrix?

(in the Inner Membrane of mitochondria)

The matrix contains a complex mixture of soluble enzymes that catalyze the respiration of pyruvic acid and other small organic molecules.

Here pyruvic acid is

• oxidized by NAD⁺ producing NADH + H⁺
• decarboxylated producing a molecule of
  • carbon dioxide (CO₂) and
  • a 2-carbon fragment of acetate bound to coenzyme A forming acetyl-CoA

3 complexes of integral membrane proteins, the NADH dehydrogenase complex (I) the cytochrome c reductase complex (III) the cytochrome c oxidase complex (IV) and two freely-diffusible molecules ubiquinone, and cytochrome c

that shuttle electrons from one complex to the next.

What happens in the Citric Acid Cycle?

The final step regenerates a molecule of oxaloacetic acid and the cycle is ready to turn again.

This is the summary of...

Each of the 3 carbon atoms present in the pyruvate that entered the mitochondrion leaves as a molecule of carbon dioxide (CO₂).

At 4 steps, a pair of electrons (2e^-) is removed and transferred to NAD⁺ reducing it to NADH + H⁺.

At one step, a pair of electrons is removed from succinic acid and reduces FAD to FADH₂.

 electrons of NADH and FADH₂  transferred?

The electrons of NADH and FADH₂ are transferred to the electron transport chain.

the stepwise transfer of electrons from NADH (and FADH₂) to oxygen molecules to form (with the aid of protons) water molecules (H₂O) happens in ________________.

(Cytochrome c can only transfer one electron at a time, so cytochrome c oxidase must wait until it has accumulated 4 of them before it can react with oxygen.)

True or False?

Approximately 20 protons are pumped into the intermembrane space as the 4 electrons needed to reduce oxygen to water pass through the respiratory chain.

The gradient of protons formed across the inner membrane by this process of __________ transport forms a miniature battery.

active? or passive?

Active

The protons can flow back down this gradient, reentering the matrix, only through another complex of integral proteins in the inner membrane, the ATP synthase

The energy released as electrons pass down the gradient from NADH to oxygen is harnessed by three enzyme complexes of the respiratory chain (I, III, and IV) to pump protons (H⁺) against their concentration gradient from the matrix of the mitochondrion into the intermembrane space.

TRUE OR FALSE.

As the proton's concentration increases there (which is the same as saying that the pH decreases), a strong diffusion gradient is set up. The only exit for these protons is through the ATP synthase complex. As in chloroplasts, the energy released as these protons flow down their gradient is harnessed to the synthesis of ATP. The process is called ___________ and is an example of facilitated diffusion.

Most of the ATP is generated by the proton gradient that develops across the ____________.

How many protons are produced from NADH to oxygen through the respiratory chain?

How about with FADH_2?

3 (NADH) , and then 2 (FADH₂). 

The number of protons pumped out as electrons drop from NADH through the respiratory chain to oxygen is theoretically large enough to generate, as they return through ATP synthase, 3 ATPs per electron pair (but only 2 ATPs for each pair donated by FADH₂).

• 10 by NAD⁺ (so 10x3=30); and

• 2 by FADH₂ (so 2x2=4),

this could generate 34 ATPs. Add to this the 4 ATPs that are generated by the 3 exceptions and one arrives at 38.

But The energy stored in the proton gradient is also used for the active transport of several molecules and ions through the ____________ into the ______.

TRUE or FALSE?

NADH is also used as increasing agent for many cellular reactions.