As we transition from talking about aerobic
respiration to anaerobic respiration or fermentation, we want to spend a few minutes just talking
about ATP that you get from these processes. One of the things that you should understand
is that glycolysis is really speedy, but it doesn't produce a lot of energy. So remember
in glycolysis you had a net production of only two ATP, per glucose molecule. And I
like think of glycolysis is kind of like a Ferrari. It's fast but it's not very efficient,
right - so you burn a lot of gas, you go really fast but you waste a lot of fuel. And when
there's oxygen present you can then go through the Krebs cycle and the electron transport
chain and this is really slow. So from a cellular point of view, this process takes a lot longer,
but in a bacteria, you can get 38 ATP per molecule of glucose. So compare 38 ATP to
only two ATP, you know the gas mileage, for lack of a better term, in an aerobically respiring
cell is a lot more efficient. So I've got a picture of a Prius here, although I think
I should probably have a picture of an electric car like a Leaf or something instead. Now
there's a lot of those around. If you've ever driven a Prius, you probably know that when
you step on the gas, not a whole lot happens, but you do get there eventually. So I think
the Prius is a really good analogy for aerobic respiration. Now as we begin to talk about
fermentation I want to point out that fermentation does not use the Krebs cycle or the electron
transport chain, and that means fermentation is inefficient. It's fast, but it's inefficient.
Your muscle cells undergo fermentation, when they produce lactic acid. So you're running
up the stairs because you're late to class. And you are out of breath at the top, you're
actually recovering from doing some anaerobic respiring (really fermentation) your, your
muscle cells can do this briefly they can do it for very long but they can produce lots
of ATP really quickly because you're using, you're using the Ferrari to get up the stairs,
but you will be out of breath for a while until your liver has taken back up the lactic
acid and converted it back to pyruvate and ultimately generated lots of ATP from it.
Okay, let's move on now and talk about fermentation and I know this was short but I'm going to
show you first an Amoeba Sisters, animation, and the first part of the animation, she actually
spends a lot of time reviewing cellular respiration in the presence of oxygen, but then she moves
on into kind of a nice comparison to fermentation and then we're gonna dive a little bit more
deeply into it ourselves.