00:01
Here we're going to follow the flow of energy from sunlight to atp via chemoasmosis in the thylacoid membrane of a chloroplast.
00:10
Okay, so just as a reminder, looking at a chloroplast here, when we are zoomed in on one thylacoid membrane, we see this cross section right here with an electron transport chain with some enzymes called atp synthase.
00:26
And it all starts with photosystem 2.
00:30
Solar energy will be absorbed by the chlorophyll in photosystem 2, and it excites a series of electrons.
00:39
They're going to go flow through this electron chain all the way up until it makes another chemical energy called nadph, which is another topic that we'll talk about.
00:51
But as these electrons are flowing, they end up powering the active transport of hydrogen ions into the lumen.
01:03
Now, there's already a high concentration of hydrogen ions in the lumen, and that's why it requires energy to get more hydrogen ions in the lumen, because it's moving from an area of low concentration to high concentration.
01:15
And it's not using atp here.
01:17
It's using the flow of the electrons through that electron transport chain...