At the end of Glycolysis, _______ molecules of ATP and __________ molecules of NADH have been formed. Also, two 3-carbon molecules of ____________________ remain. These are still located in the ____________________ of the cell where Glycolysis occured. For AEROBIC respiration to occur, they must enter the ____________________.

Draw a Mitochondrion and label:

- intermembrane compartment (outer compartment)

- matrix

- inner membrane

- outer membrane

- cristae


The Matrix Rxns are enzyme-catalyzed rxns that take place in the jelly-like ____________________ of the mitochondrion. They occur ___________ for every pyruvate entering; thus ____________ for every glucose molecule. The Matrix Rxns include:

Preparatory Steps/Conversions

The purpose of these rxns is to convert __________________ to acetyl-CoA (a 2-carbon molecule) which enters the Citric Acid (Krebs) Cycle.

  1. __________________ is oxidized as it loses 2 electrons and 1 H+ to _______________. This produces NADH (reduced nicotinamide adenine dinucleotide), an electron carrier molecule. NADH will be used later in the ETS.

  2. There is an addition of a molecule called ____________ ____ and the loss of a CO2.

Citric Acid (Krebs) Cycle

  1. The 2-carbon molecule, ____________________ ______ becomes attached to the 4-carbon Krebs cycle "acceptor" molecule, ____________________. This forms the 6-carbon molecule, ____________________, for which the cylce is named.

  2. Citrate is converted into the 6-carbon ____________________.

  3. ____________________ loses a ____________________ and 2 electrons to the electron carrier, _______. In this reaction, NAD+ is _______________ and isocitrate is _______________. Isocitrate also releases _____________. This leaves a 5-carbon molecule of ___________________.

  4. ____________________ also gives up H+ and electrons to ___________________ to produce NADH. A coenzyme-A molecule is added. Again, a ____________ is released. The product of these reactions is ______________________.

  5. Briefly, a _______________ group binds to the succinyl-CoA and is then transferred to __________ to produce GTP (guanosine triphosphate, a type of high-energy molecule similar to ______). GTP then donates the _______________ group to __________ to produce one molecule of ____________. This leaves a 4-carbon molecule of ___________________.

  6. Succinate transfers 2 H+ and 2 electrons to ___________ (flavin adenine dinucleotide, another type of electron carrier molecule) producing _______________. Thus, FAD has been _______________ and succinate has been __________________. The molecule _________________ remains. FADH2 will be used later in the ETS.

  7. H2O is added to fumarate to produce ____________________.

  8. _________________ reduces ____________ to produce ______________. This reaction regenerates the original "acceptor" molecule of Krebs cycle, ________________________. This acceptor molecule can now unite with another ____________________ _____ to start the cycle again.

Summary of Products

For each pyruvate molecule: _______ CO2, ________ ATP, __________ NADH and _____ FADH2.
For each glucose molecule: _______ CO2, ________ ATP, __________ NADH and _____ FADH2.

The Matrix Rxns are considered part of aerobic cellular respiration. Soon you will see why oxygen is necessary.

Explain why oxygen is needed for the Matrix Rxns: