In this video, we're going to introduce our map of the lesson on photosynthesis, which is down below right here. At this point in our course, we know that photosynthesis occurs in the chloroplast. The big green structure that we have in the background represents the chloroplast. Now moving forward in our course, we're going to be talking about photosynthesis as it occurs with open stomata, and recall that the stomata are the openings or the pores that are found in the leaves.
When the stomata are open, this allows for gas exchange; it enables carbon dioxide in the atmosphere to diffuse into the leaf, and it allows oxygen that's produced from the light reactions to diffuse out of the leaf. When the stomata are open, the light reactions and the Calvin cycle reactions will proceed as normal. As we move forward in our course, we'll talk about the situation when the stomata are open, specifically we're going to talk more about the light reaction moving forward, and then after we talk about the light reaction we are going to discuss the Calvin cycle reaction and how the Calvin cycle leads to the production of glucose.
Then once we talk about the light reactions and the Calvin cycle, we'll then switch our attention to what happens when the stomata are closed, preventing gas exchange so that carbon dioxide cannot come into the plant and oxygen cannot leave the plant. Under those conditions, there's a process that's called photorespiration, C3 photorespiration that we will talk about later in our course. And then we'll talk about how some plants have been able to evolve pathways to avoid photorespiration, including C4 plants and CAM plants.
Once again, we'll get to talk about this portion of our map later in our course in a different video. But for now, because this is a map of the lesson on photosynthesis, you can use this image like a map to make predictions about what we're going to talk about next. So we're going to follow the leftmost branches first. We'll talk about the light reactions then we'll talk about the Calvin cycle reactions, and then after we've completed the leftmost branches, once again, we'll start to talk about the right branches.
This here concludes our introduction to the map of the lesson on photosynthesis, and we'll be able to talk more about the light reactions in our next lesson video. So, I'll see you all there.
