Pigments of Photosynthesis - Video Tutorials & Practice Problems

Pigments of Photosynthesis

in this video, we're going to begin our lesson on pigments of photo systems. But really, we're gonna start off focusing on pigments and will define what photo systems are a little bit later in our course in a different video. And so what you need to know now is that in order for plants to harness the light energy that's required to power photosynthesis, chloroplasts, the site of photosynthesis, need to have several different types of pigments. And so, ultimately, what we're saying here is that these pigments, they're really important for driving photosynthesis because they allow for the harnessing of the light energy. And so what exactly are these pigments? Well, pigments are defined as molecules that have this amazing ability to absorb wavelengths of visible light. And when these wavelengths of visible light are absorbed, they can be utilized to power photosynthesis. Now, the main pigment that you all should be aware of is chlorophyll. A and chlorophyll is not to be confused with chloroplast. Remember, chloroplasts are organelles. That serve is the site of photosynthesis and Cora Phil. Even though it sounds like chloroplasts, it's not the same thing as chloroplast. Chlorophyll is once again a type of pigment and in fact, chlorophyll. A is the main photosynthetic pigment that air found within chloroplasts now chlorophyll A. Even though it is the main photosynthetic pigments, it's not the Onley photosynthetic pigment, and so accessory pigments are pretty much all of the other photosynthetic pigments that air, not chlorophyll A. Now it's important to note that different pigments are going to absorb different wavelengths of light. And so it's also important to note that some wavelengths of light are actually going to be absorbed and utilized to drive photosynthesis. But other wavelengths of light are not going to be absorbed. Instead, these other wavelengths of light will be reflected, and the reflected light is really the light that we end up visualizing with our eyes. And so some wavelengths of light are absorbed. Others are reflected. We visualized the reflected wavelengths of light, but the absorbed wavelengths of light is really the light that is being used to drive photosynthesis, not reflected life. And so let's take a look at our image down below to get a better understanding of the different types of photosynthetic pigments. And so across the top here we have the name of the different photosynthetic pigments and across the bottom here, what we're showing you are the light that's being reflected by these particular photosynthetic pigments. And so here in this first column, what we're showing you is the main photosynthetic pigments, Which is, of course, chlorophyll A and chlorophyll A which will notice eyes. It's gonna be pigments found within the chloroplast, which are found again within the missile fuel cells of the leaf tissue. Uh, it is going to mainly reflect green and blue, and so you can see that green wavelengths of light are reflected almost the most. And so here you can see the I. This would be our eyes looking at the plant. And so the reason that we perceive plants to be green is because they reflect green wavelengths of light. And so we end up visualizing those green wavelengths of light. But notice that the other wavelengths of light here, like yellow and orange, and so on these air gonna be absorbed by chlorophyll. A. And, uh, that energy that is absorbed is gonna be used to power photosynthesis. But notice over here in this next column, what we have is a different type of chlorophyll, which is chlorophyll B and chlorophyll. B is not as predominant is chlorophyll A. It's found in smaller amounts and chlorophyll be notice. It actually reflects different wavelengths of light. It actually reflects mainly yellow and green wavelengths of light. So the yellow wavelength of light here is being detected by our eyes because that's the light that's being reflected. And so we can perceive chlorophyll B as being yellow in color. But once again it absorbs all of these other wavelengths of light, and those can be utilized to drive photosynthesis and then last but not least over here on the far right. What we have are the keratin noise, and the carotenoids has this little carrot prefix in here, which can remind you of the carrots themselves. And these mainly reflect orange, red and yellow wavelengths. And so you can see the orange wavelength of light being reflected here. And so we can see these as being orange because this is the light that's being reflected. But once again, the other wavelengths of light are being absorbed and utilized on DSO. This here really concludes our brief introduction to the pigments of photo systems, and as we move forward in our course will continue to talk mawr about pigments and will also introduce photo systems as well. So I'll see you all in our next video.

Examples of accessory pigments for photosynthesis are:

a) Chlorophyll b and carotenoids.

b) Chlorophyll a and chlorophyll b.

c) Chlorophyll a and carotenoids.

d) Carotenoids, chlorophyll b and chlorophyll a.

• A. Chlorophyll b and carotenoids.
• B. Chlorophyll a and chlorophyll b.
• C. Chlorophyll a and carotenoids.
• D. Carotenoids, chlorophyll b and chlorophyll a.

Absorption Spectrum of Photosynthesis

and this video were briefly going to talk about the absorption spectrum of photosynthesis. And so an absorption spectrum is really just a graph that shows the light absorption of pigment molecules and so down below notice that we're showing you a pigment light absorption spectrum and so notice that we have on the Y axis the absorption of light so low on the Y axis represents a low amount of light being absorbed and high on the Y axis represent, ah, lot of light being absorbed and then down below on the x axis. Notice that we have the particular wavelength of light and nanometers, essentially just showing you the, uh visible wavelength of light here. And so it's important to note is that on this particular spectrum, we're showing you the curves for three different pigments. We're showing you chlorophyll, a in green chlorophyll be here and yellow and the carotenoids here in the oranges. Dark oranges color here, and so you can see the spectrums for each of these curves throughout here. And, uh, you can see these curves throughout, and so it's important to note eyes that these curves are just showing the amount of light that's being absorbed at a particular wavelength. And so what you'll notice is that wavelengths that fall into this region right here are mainly being absorbed. And so you can see this region here having the absorbed label. Um And then you can also see that wavelengths over here in this region are also mainly being absorbed. Um, not by all of the pigments, but by the collection of them together. But what you'll notice is that right here in this region, most of these wavelengths basically greenish and yellowish, they're not really being absorbed. And so, for our purposes here, we can just basically assume that these wavelengths here are being reflected so we can go ahead and say that these are being reflected here in this middle region from here to here. Since there's not a lot of peaks here, there's not a lot of absorption going on, so they're being reflected. And so really, that's the biggest take away here is that different pigments are going to absorb and reflect different wavelengths of light, but collectively it's going to be the amount of them and the particular wavelengths of light that are reflected that dictates the colors that we end up seeing in the plants. And so this year concludes our brief introduction to an absorption spectrum, and we'll be able to get some practice as we move along in our course, So I'll see you all in our next video.

Which of the following pigments does NOT absorb yellow/orange light (650-750nm)?

a) Chlorophyll a.

b) Carotenoids.

c) Chlorophyll b.

d)  Both a & c.

• A. Chlorophyll a.
• B. Carotenoids.
• C. Chlorophyll b.
• D. Both a and c.

Introduction to Photosystems

in this video, we're going to begin our introduction to photo systems. And so photo systems are defined as complexes of pigments, proteins and other molecules as well that are found in the Fila coid membrane. And so recall from our previous lesson videos that these Thilo coins are the green pancake looking structures that air found inside of chloroplasts. And so to refresh your memory down below, over here on the left hand side, we're showing you the image of the chloroplasts organelles and recall that on the inside of these chloroplasts organelles are these green looking pancake structures that you see without and these green looking pancake structures are again called Fila Coy AIDS. And so, if we zoom into just one of these green looking pancake structures here, that is where we're going to find the photo system. And so notice in this image here, this is representing the membrane of the Thilo Coid. So we have the Thilo Coid membrane here on one side of the hill, a coid membrane. We have the Thilo Coid space, which is the inside of the Thilo Coid, the inside of the green pancake itself and then above the Thilo coid membrane. We have the stromal, which is just outside of the green pancake, but still inside of the chloroplast. And so notice that embedded within the Thilo coid membrane, this is where we find our photo system, This complex of pigments, proteins and other molecules found in the Thilo coid membrane. Now, photo systems are composed of several light harvesting complexes that surround a reaction center and notice that we have our light harvesting complexes color coded here in this purplish color which color codes to the purplish colors that we see down below. And we also have the reaction center up above. That's an orange that color codes of the reaction center that we have down below. And so if we take a look at our image down below, notice once again that here in purple, over here and over here we have this light harvesting complex so we could go ahead and label them as the light harvesting complexes and within the light harvesting complex, uh, noticed that, uh, I'm sorry. Surround the light harvesting complexes that you see here and over here on the right, notice that they're surrounding, uh, this center region here, which has the reaction center. You could see the reaction center is here in orange, right here in the middle, surrounded by light harvesting complexes as we described up above. And so, within the light harvesting complex, which will notice are the There are these teal circles and these teal circles here represent accessory pigments. And these accessory pigments are going to be helpful and absorbing photons of light. And so you can see photons of light here are interacting with the light harvesting complex, as its name implies, and it's able to interact with light because of these accessory pigments that absorb light. And so, if we take a look at the reaction center once again here in the middle, notice that the reaction center has these two green molecules right here that are chlorophyll a molecules, the predominant pigment found inside of chloroplasts on also notice that in red right here there is the primary electron, except which we'll get to talk more about later in our course. But for now, what we can see is that this photo system here is gonna be really, really important for absorbing light on allowing chloroplast to absorb light. And that's again because it contains accessory pigments, and it contains the predominant pigment chlorophyll egg. Now, as we move forward in our course, we'll get to talk Maura about photo systems and how they're involved and what's known as the light reaction, which again, we'll talk about Mawr in a later video later in our course. But what's important to note now is that most plants are actually going to have to photo systems, and these two photo systems once again are gonna be involved with performing the light reactions of photosynthesis, which again, we'll get to talk about these late reactions of photosynthesis later in our course. But for now, this is our brief introduction to photo systems. How photo systems are found inside of the membranes of Thill, a coid thes green pancake structures within chloroplasts and how photo systems are important for absorbing light and are involved with light reactions. So we'll be able to get some practice applying some of these concepts as we move forward in our course. So I'll see you all in our next video

The figure shows the absorption spectrum for chlorophyll a and the action spectrum for photosynthesis. Why are they different?

a) Green and yellow wavelengths of light inhibit the absorption of red and blue wavelengths.

b) Oxygen given off during photosynthesis interferes with the absorption of light.

c) Accessory pigments are absorbing light in addition to chlorophyll a which can be used in photosynthesis.

d) Aerobic bacteria take up oxygen, which changes the measurement of the rate of photosynthesis.

• A. Green and yellow wavelengths of light inhibit the absorption of red and blue wavelengths.
• B. Oxygen given off during photosynthesis interferes with the absorption of light.
• C. Accessory pigments are absorbing light in addition to chlorophyll a which can be used in photosynthesis.
• D. Aerobic bacteria take up oxygen, which changes the measurement of the rate of photosynthesis.