Diffusion and the
Mitochondria
Concentration terms (notes)
• Solute: what is being dissolved
• Solvent: what is doing the dissolving
• Solution: a mixture of a solute and solvent
• Molarity: a measure of concentration. It is
denoted by a capital “M”
No relation to the burrowing
sort of mole
• (Not notes): 5 M reads as “five molar”
• (Not notes): the units are mols/L
This will show up again when you take chemistry, just you wait!
Examples of solutions (not notes)
Solutes: sugar, CO2
Solvent: water
Solute: salt
Solvent: water
Solute: fullerene
Solvent: benzene
Molarity (not notes)
• Molarity is useful because it lets us compare concentrations between
different solutions
• For example, if I were to have a 3M and 8M solution I would know
that the 8M solution is more concentrated
• Molarity is like density for solutions: it doesn’t tell you how much
total solution you have, just how much solute is packed into your
solvent
Diffusion Revisited (notes)
• Diffusion is the movement of molecules from a high concentration to a low
concentration
• In other words: diffusion is the movement of the solute from a high
molarity to a low molarity.
• It will keep trying to move until the molarity is equal
2M
8M
5M
= solute
5M
Mitochondria (notes)
• Function: to generate energy for the cell
• Every cell has many mitochondria
• Energy is in the form of a molecule called ATP
• (Not notes): ATP stands for “adenosine triphosphate”
How Mitochondria Work (not notes)
• Mitochondria have a 2-layered membrane with a space between
them. They pump this space full of protons (H+), and then harnesses
their diffusion out to generate ATP.
• You can think of this process like a dam: by using a substance that
wants to move somewhere on its own (water downhill, H+ to a lower
concentration) it can harness this energy to do something else
(generate electricity, produce ATP)
(Diagram on next slide)
ATP synthase in action:
https://www.youtube.com/watch?v=PjdPTY1wHdQ
Fun Facts About the Mitochondria (notes)
• Mitochondria were originally a separate cell that was taken in by a
larger cell
• Mitochondria allow cells to produce fifteen times as much energy as
they could otherwise
• Mitochondria have their own DNA and ribosomes (one of the hints
they were originally separate cells)