Well we finally got some days off due to snow THANK GOD, but that did nothing to stop the train known as AP Bio class. This week we got more into photosynthesis specifically the reactions and the two photo systems.
- The overall structure of the chloroplast looks like the diagram above, the chloroplast is responsible for photosynthesis in plant cells. Photosynthesis takes place on the Thylakoids of the chloroplast. In light dependent reactions, sunlight is absorbed by chlorophyll. In light independent reactions, the Calvin cycle occurs and carbs are assembled. Thylakoids are the flattened sacks inside the chloroplast, this is where light reactions of photosynthesis take place. The stroma is the fluid-filled space that is surrounding the grana, and is also involved in the synthesis of organic molecules from water and carbon dioxide. This stroma function is generally known as either the light independent reactions or the dark reactions. Photosystem II I will talk about first because it actually occurs first (scientist are just lazy af). I am going to refer to the photo systems as P1 and P2 (just remember reversed order). P2 is the first light-dependent reactions of photosynthesis. It is located in the thylakoid membrane of plants. By replenishing lost electrons with electrons from the splitting of water, P2 provides the electrons for all of photosynthesis to occur. P1 (second part) is responsible for providing high energy electrons to reduce NADP+ and produce NADPH to be used in the Calvin cycle. ATP synthase is pretty much a pump, it is responsible for powering our cellular processes. The electron transport chain uses the electrons from electron carriers to create a chemical gradient that can be used to power oxidative phosphorylation. In the Calvin cycle, carbon atoms are incorporated into organic molecules and used to build three-carbon sugars. This process is fueled by, and dependent on, ATP and NADPH from the light reactions. It is not light dependent though.