Stages of Photosynthesis

in this video, we're going to briefly introduce the stages of photosynthesis. And so photosynthesis actually occurs in two stages that we have numbered down below. And so the first stage of photosynthesis is the light reactions, and the second stage of photosynthesis is the Calvin cycle, and so moving forward in our course, we're going to talk a lot more details about both the light reactions and the Calvin cycle as well. But here in this video, we're just introducing these two stages. And so the light reactions, as their name implies, is going to convert light or photons and water into chemical, energy and oxygen gas. And the Calvin Cycle is going to use carbon dioxide from the atmosphere, as well as the chemical energy that was formed by the light reactions in order to synthesize glucose, the sugar, and so down below. In our image, we can see the stages of photosynthesis, and we know that the chloroplast acts as the site of photosynthesis and so notice that end the background here in green. What we're showing you is the chloroplast, the site of photosynthesis. But inside of the chloroplast, photosynthesis is broken up into two stages the first stage are the light reactions, which occur inside of the hill, a koi aids. And again, we'll talk a lot more about the light reactions as we move forward in our course. And then the second stage of photosynthesis are the Calvin cycle reactions, which are going to occur in the strom A of the chloroplast. And so what you can see here is when with light reactions, which is the first stage of photosynthesis, it uses light. It uses photons of light from the sun, and it also uses water. And so these two reactions come in. And what comes out our eyes oxygen, gas and chemical energy that's used to power the Calvin cycle. And so that's basically what we've described here for the light reactions now for the Calvin Cycle. Notice that it's going to use carbon dioxide from the atmosphere, along with chemical energy that was produced by the light reactions, and it's gonna use both of those to generate glucose. And so ultimately, what you can see is that coming into the chloroplast is solar energy, water and carbon dioxide, these air things that all come into the chloroplast and the things that come out of the chloroplast, our oxygen, gas and glucose. And so those are the products of photosynthesis, as we've discussed in our previous videos. And so again, we're going to talk a lot. Maura, about each of these stages of photosynthesis, the light reaction and the Calvin cycle as we move forward in our course. But for now, this here concludes our brief introduction to the two stages of photosynthesis, and I'll see you all in our next video.

in this video, we're going to introduce our map of the lesson on photosynthesis, which is down below right here. And so at this point in our course, we know that photosynthesis occurs in the chloroplast. And so the big green structure that we have in the background represents the chloroplast now moving forward in our course, we're gonna be talking about photosynthesis as it occurs with open still mata and recall that the still mata are the openings or the pores that are found in the leaves. And so when the Samata are open, this allows for gas exchange. It allows for carbon dioxide in the atmosphere to defuse into the leaf, and it allows oxygen that's produced from the light reactions to diffuse out of the leaf. And so when the Samata are open, the light reactions and the Calvin cycle reactions will proceed as normal. And so as we move forward in our course, we'll talk about the situation when this Tamada are open. Uh, specifically, we're gonna talk more details about the light reaction moving forward. And then after we talk about the light reaction, we're going to talk about the Calvin cycle reaction and how the Calvin cycle leads to the production of Glucose. Then once we talk about the lights, reactions in the Calvin cycle will then switch our attention to what happens when the Samata are closed, preventing gas exchange so that carbon dioxide cannot come into the plant and oxygen cannot leave the plant. And so, under those conditions there's a process that's called photo respiration C three photo, respiration that we will talk about later in our course. And then we'll talk about how some plants have been ableto evolve pathways to avoid photo respiration, including C four plants and cam plants. And 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 gonna follow the left most branches first, so we'll talk about the light reactions, and then we'll talk about the Calvin Cycle reactions. And then, after we've completed the Left most branches, once again, we'll start to talk about the right branches and so this here concludes our introduction to the map of the lesson on photosynthesis, and we'll be able to talk mawr about the light reactions in our next lesson video, so I'll see you all there.