before diving into the details of photo phosphor elation. I just want to talk about something that's really cool in terms of the evolution of these biochemical processes that we've been talking about and that we're about to talk about. And that's that autotrophs, which get their energy from the sun as a product of their metabolic reactions, produce carbohydrates and oxygen, whereas hetero tropes like us we, through oxidative phosphor elation, the processes we were just talking about. We produce carbon dioxide right from the citric acid cycle. Oops! And water from oxygen receiving electrons in the electron transport chain. So just really cool how there's this reciprocity between the inputs and outputs of these metabolic pathways. Now let's actually jump in. Talk a little bit about photo phosphor relation, which is, uh, the synthesis of ATP from photosynthesis. And it's going to require these photo pigments, which are molecules that can absorb sunlight. Energy in the form of photons and the main photosynthetic pigments is chlorophyll A. This molecule right here, says chlorophyll A. And you can see it contains a poor friend ring right here and in the center of that. Unlike the portrait rings we saw inside a chrome's. This has a magnesium, and this molecule is going to absorb light maximally at a wavelength of 680 nanometers. Now, photosynthetic organisms also use accessory pigments to broaden the range of light that they're able to use for photosynthetic. Process is so they will use molecules like chlorophyll be and the carotenoids. And if you notice the word carrot in there, that's because this molecule right here beta carotene, which is a carotenoid, is in high concentration in carrots. Carrots have a ton of beta carotene in them. It's actually what gives them their orange color. Now, uh, you might also notice that beta carotene has these I supreme units, and that is characteristic of the character noise they all have. I Supremes, these other molecules that are used to absorb light called Fico by islands. Here's one right here could see that they have a tetra parole right? 123 and four. And that's just like chlorophyll right here, right? Look at the poor foreign ring and chlorophyll. It also has four paroles in it, right, except it's in a ring form, whereas in Fico, Beilin's their linear, so these molecules absorb light. And we, uh, call the spectrum of light that they're able to absorb the absorption spectrum, and you can see their absorption, the absorption spectrums of chlorophyll A and chlorophyll. Be right here and notice how they kind of compliment each other. Chlorophyll B has stronger absorbency in this region. Chlorophyll A has stronger absorb INTs in this region. Now the plot of photosynthetic activity against wavelength of light is called an action spectrum. That's what this is over here. This is an action spectrum, so you can see that on the Y axis, we have the rate of photosynthesis. And as you can see, there's a correlation between the rate of photosynthesis right and the absorption ranges of the photo pigments. So hopefully you can get why the rate of photosynthesis will be highest in the range is where these molecules are able to best absorb light because light is powering photosynthesis. Essentially, with that, let's flip the page
