Once you understand the light dependent reactions, the light independent reactions, and how these two sets of interactions are linked together then you understand the basics of photosynthesis. The pattern of photosythesis that we have discussed so far is known as "C3 photosynthesis" (it is named this becasue the first stable product of the Calvin Cycle is a molecule that contains three carbon atoms). C3 photosynthesis is considered to be the basic mechanism of photosynthesis.
As I have mentioned in class the best way to assure that you understand what is going on is that you should be able to describe photosynthesis at different levels of detail.
1) the one sentence answer
2) the one paragraph answer
3) the full detail answer
In my experience, students quickly get lost by worrying about the details. Thus, I suggest that you start at the one sentence answer, then move to the one paragraph answer, and finally finish up with the full detail answer. You will find that by thinking about the one sentence and the one paragraph answers you will have already figured out how to organize your full detail answer.
I suggest that you try writing out the answers to these questions at the three levels.
1) What is photosynthesis?
2) What are the light dependent reactions of photosynthesis?
3) What are the light independent reactions of photosynthesis?
4) What is a photosystem?
I encourage you to post your answers here and then to provide critical feedback to your classmates about their answers.
1) What is Photosynthesis?
ReplyDeleteone sentence: Photosynthesis is the process by which light energy with the addition of CO2 from the atmosphere is ultimately converted into chemical energy held in the bonds of glucose.
Paragraph: Photosynthesis involves two fundamental processes that result in the conversion of light energy into ATP and NADPH which is subsequently used in the conversion of CO2 into glucose. The production of ATP and NADPH are the result of light energy being used in systems known as PSI and PSII. These photosystem reactions involve the conversion of light energy into potential energy held in an excited electron which absorb light photons and move to a higher energy level. Through a series of steps the energy released from electrons falling back to their ground state causes formation of a H+ concentration gradient. This concentration gradient powers chemiosmosis that results in the formation of ATP in PSI and ATP and NADPH in PSII(which requires an additional photon of light). The light dependent reactions of photosynthesis are responsible for the conversion of light energy into ATP and NADPH. These reactions are so named because they rely on light or photons to power them. The light independent reactions are so named because these reactions use the ATP and NADPH created in the light dependent reactions to convert CO2 into glucose thereby needing light indirectly rather than directly to power the conversions. The series of steps involved in the conversion of CO2 into glucose by using ATP and NADPH is known as the Calvin Cycle. The end result of photosynthesis is the production of oxygen as a byproduct and the creation of a long term energy storage(glucose) for the primary producer or photosynthetic organism both of which are crucial for the survival of all organisms on earth.
***The long version would be really extensive of course so I wont write it here. It would go into more detail for PSI PSII and Calvin cycle and other aspects as well.
"This concentration gradient powers chemiosmosis that results in the formation of ATP in PSI and ATP and NADPH in PSII(which requires an additional photon of light)"
ReplyDeleteI'm confused, i thought that ATP was formed in PS II and NADPH was formed in PSI?