The Mitochondrion

The mitochondrion is the organelle where most of ATP production occurs. See diagram below

Glycolysis takes place in the cell cytoplasm

Words to go with Glycolysis:

Pyruvate
Pyruvic acid
Oxidation
Dehydrogenase
Energy substrates (glucose, lipids, proteins)
Phosphate
ATP
ADP

ATP (adenosine triphosphate) The Universal energy Molecule

The Link Reaction takes place between the cytoplasm and the mitochondrion

The Kreb’s Cycle takes places in the matrix of the mitochondrion

Words to go with The Kreb's Cycle (aka The Citric Acid Cycle)

Citric acid cycle
CO2
FADH2
NADH + H+
NAD+
Acetyl CoA – formed in the mitochondrion from pyruvate

Oxidative Phosphorylation (Electron Transport Chain or ETC) takes place in the inner mitochondrial membrane

It uses the inner mitochondrial membrane which faces the inter-membrane space of the mitochondrion.

It uses both the intermembrane space on one side and the matrix of the mitochondrion on the other side, to form a concentration gradient for H⁺ ions (= protons).

Protein channels allow H⁺ions (protons) to move from where they are at a higher concentration to where they are at a lower concentration.

So, when H⁺ ions (protons) are at a higher concentration in the matrix but at a lower concentration in the intermembrane space, they move through the protein channels into the latter.

This means that H⁺ ions (protons) are then at a higher concentration in the intermembrane space! What happens? They move back into the matrix, via a protein channel, because the concentration gradient has reversed.

The channel protein is actually ATP synthase – it’s trapped in the inner membrane and there are so many of them, they can be captured on film using an electron microscope.

It’s like a shuttle of back and forth across the inner membrane space.

Words to go with ETC:

Intermembrane space
Matrix
Chemiosmosis
Proton pumps
Concentration gradient
ATP synthase
Carrier molecules
Oxidation
Reduction
Cytochromes
Transport proteins

QUESTIONS

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