So, in the last video, we covered respiration, focusing aerobic respiration. Now let's talk about photosynthesis.
This unit we have several learning objectives to the final words, talk about structures that diagram the flow of electrons and then talk about the steps needs light dependent and independent processes.
Photosynthesis works to convert light energy into chemical energy. And it's used by our phototropes.
It involves two major processes, like, dependent capture of light energy that occurs and by the quotes and then the simulation of carbon turning, carbon dioxide into carbohydrates and this is considered a light independent process.
Now, if you look at the formula, it should look familiar to you as it's almost the reverse of respiration here.
We're gonna use carbon dioxide to eventually I sugar these two reactions occur in our core class, which have a membranous structure.
The light harvesting is going to be done sequentially by photo systems here and then eventually the definitive independent process will occur in the space and stroma. Not in the membrane structure.
And the light harvesting, it's done by systems called photo assistance and photo systems are gonna use pigments to capture. Right? And then pass that energy. Those electrons eventually to a reaction center.
We have a pair of chlorophyll. Chlorophyll are named rather optimal wavelength, six hundred and eighty or seven hundred.
No, I said that photo systems use pigments, like chlorophyll to capture photons, avoid chlorophyll has a core front ring structure that allows it to absorb the photon and pass electrons through this.
Ray it is anchored into the membrane by it's pilot tall side chain. We also have other pigments accessory things like, which have other optional wavelengths and can assist in light capture.
So photosynthesis also uses a different electron carrier. So we talked about respiration and any. D plus and ndh respiration. Very similar. Structurally an extra phosphate. Here.
We get an eighty P plus and eighty P. H. keep in mind for photos and shown here as the energy diagram. So photosynthesis is going to start a non sequence of electrons.
We start with our second photosystem. I apologize for the nomenclature. This was, they were named in the order that they were discovered as opposed to the order in which they work. So, we start with P.
S to photosystem to and it's gonna strip electrons to muscles of water, pumping hydrogens into the fat limit and releasing oxygen.
Now, those electrons are going to be excited in that P, six, eighty core healthcare and they're going to bump up to a higher energy level, those excited electrons and pass along.
Eventually reaching our excited from complex.
Which is going to pump protons even more proton and then will pass those electrons for a second but a system a system one yes one to our second horrible reaction pair.
He's seven hundred, which will again observe photons of white and bump it to a higher energy state.
No, those electrons can flow through and we'll eventually be used and transferred to reduce any pH, our electron carrier.
Like, in the mitochondria, the movement of electrons and protons gradient is coupled to synthesis of.
Is going to use that proton gradient that we make in our lumen to begin using a very similar structure move that protons back down. It's gradient and use that energy to make an eighty P molecules.
Now, if the cell needs more, then it can generate just with that those few. It can then do cyclical electrons.
So, rather than wasting the electrons on a pH, it can pass them back to the site from complex, which will use it to pump even more keep in mind that the protons are the thing that moves through the base creating it.
So, I can pass them to the cytochrome complex, which then pass back to PS one, which will use photons to excite. And it can go through this cyclical as many times as it needs to make to meet its energy demands.
Once the plant cell has used light to make energy cell can then use that energy to fix carbon dioxide and eventually make starch and sucrose or sugars.
This light independent process is called the Calvin cycle and again, one of the products of the Calvin cycle, we'll leave the cycle for the backbone for sure.
The Calvin cycle also has three phases. The first phase carbon dioxide is added to three molecules of one, five bisphosphate, or by an enzyme called.
And then the second phase, the three new modules are gonna be reduced, gaining electrons from.
Finally,
we're going to regenerate our acceptor or we,
and the cycle also use some,
this is the cycle again,
carbon dioxide and water going to use our electron carrier and a dph.
And some of the that we made earlier.
So, this video, we covered the process of synthesis and the next video, we're gonna cover cell signal transaction.
