Life Science Homeschool Curriculum

In chapter five, we'll discuss the structure and function of the common eukaryotic organelles, which are cytoplasm, nucleus, nucleoplasm, nucleolus, ribosome, endoplasmic reticulum, Golgi apparatus and vesicles, lysosomes, mitochondria, vacuoles, and chloroplasts. We'll also discuss photosynthesis, the set of chemical reactions plants perform to make glucose from carbon dioxide using sunlight energy, And cellular respiration, the set of chemical reactions plants and animals use to make their energy molecules by breaking down glucose. And finally, we'll discuss the relationship between photosynthesis and cellular respiration. So in this chapter, we're gonna get into a lot more of the structure and function of what we call of the organelles that are inside of the cell. So these are these individual functional units inside the cell that perform, specific actions to keep the cell healthy and help it maintain homeostasis. And remember, we talked last week, when we talked about, organelles, when we talked about the cell structure in general, we talked about the basic difference between prokaryotic and eukaryotic cells when we in regard to organelles. And we learned that prokaryotic cells really only have one type of organelle that's called the ribosome. Those are the organelles that make proteins. And eukaryotic cells have lots of other organelles packed into them to do other stuff. And so we're gonna learn about all those organelles today. We're also gonna talk a little bit about, photosynthesis and cellular respiration. And we'll actually be covering this. We've already covered it a little bit, in some other classes and we'll be covering we'll talk about it, in some classes going forward as well. But I think it's really important to show the relationship between photosynthesis and cellular respiration between the two basic processes of life that essentially keep everything alive, and how, incredibly intricate intricately related they are and how one cannot function without the other. I just I think that's really cool how that exists. And, so we'll talk a little bit more in detail about photosynthesis and cellular respiration. So photosynthesis is the set of chemical reactions that plants use using the energy from the sun. And remember, when we talk about this reason I think this is so cool is that, basically life is one huge energy transfer. It's transferring energy from the sun, transferring energy from plants to consumers, from, consumers, and then from consumers to the decomposers and then decomposers back to the plants again. It's one huge energy transfer and without any energy transfer, we don't live. All of the chemical reactions of life that we perform, you know, our cells, human cells probably perform about one billion. Each cell performs about one billion chemical reactions a second. That's kind of a lot. Each one of those chemical reactions, that's one cell, one billion chemical reactions. So there's trillions of chemical reactions occurring every second in our body. Each one of those chemical reactions requires energy. Now, that energy has to come from somewhere. Ultimately, it comes from the sun. And we're gonna see that relationship between plants taking sun energy, sunlight energy, and making glucose from it. That's photosynthesis. And then what happens once the glucose is made, how do we get energy out of that? How do we get energy for us to use? Because as we know, our bodies use energy in ATP. So, adenosine triphosphate, our bodies, our enzymes use the energy in ATP in order to make their chemical reactions work. So we got to take the glucose, we got to do something to the glucose, get energy from the glucose and store it in the ATP, and that's exactly what cellular respiration is. So we're going to talk about those relationships, talk a little bit about those chemical reactions, by the time, by the time we're done with chapter five. But first, we're going to really talk a little bit more about cells and, and their organelles. So the next section really is just a brief review on the structure of the cells up to this point. And I want to emphasize again the similarities of all cells have a cell membrane and that cell membrane, whether they're bacterial or prokaryotic cells or, eukaryotic cells, the cell membrane looks pretty much the same same. It's that lipid bilayer composed of phospholipid molecules. And then so they have a cell membrane and then they got stuff on the inside. The cytoplasm is that jelly like substance on the inside of the cell, and then they all contain DNA. And all cells, have their DNA, but they're in different places. If you are a prokaryotic cell, your DNA is contained in kind of free in the cytoplasm. It doesn't have any protective coating or any protective covering at all. The DNA is free, in the cytoplasm in an area that we call the nucleoid. But if you're a eukaryotic cell, your DNA is housed in a very special, membrane, in a very special organelle that's called, the nucleus and we'll talk a little bit about that, as we move on. So those are kind of the basic similarities and differences. I kind of summarize that in figure 5.2.1. I'm not going to go over that but if you want to take a look at it, we I just kind of summarize the differences between eukaryotic and prokaryotic cells. And then, the last thing for today, we're going to talk about organelles and kind of what they are, what they do, why we have them, some common commonalities between them. But, the basic the thing to keep in mind, so we're talking about organelles and prokaryotic cells have one organelle, ribosomes, to make proteins. So why do prokaryotic cells have organelles? Well, they only have one and that's to make proteins. Our whole system, the way that we work, the way that our, cells work is all of the instructions for how the cells supposed to work, what it's supposed to do, what it's not supposed to do, starting things, stopping things, chemical reactions, all that stuff. That's all contained, in the DNA. And the way that the DNA communicates with the rest of the cell, what it wants done, what it wants to start, to stop, etcetera, what it wants made, is through proteins. It's basically the the DNA, all of the the genes within the DNA, those little segments of of DNA that code for traits, basically code for the production of one protein. So one gene makes one protein. And when the cell wants something done, it, the DNA when the DNA wants something done, the DNA will, identify whatever that protein is that it needs to make to get done whatever it wants to have done. It makes the protein and then the cell does whatever whatever the protein tells it to do. So it's a very complicated process. But, basically, the method of communication between DNA and the rest of the cell is through proteins. So the DNA has to have some way to make proteins so that the protein can get made and then whatever thing that protein does, can get done after the protein is made. So in prokaryotic cells, they have one they got one, organelle, that's the ribosome. So basically, the DNA says, the DNA decides on what protein it wants made. That message goes to the ribosome. The ribosome reads the message, makes a protein and we're done. In the eukaryotic cell, it's a little bit more complicated again because the cell is or because the DNA is contained in its own, in its own organelle. But still, the DNA decides what protein it needs to have done to affect whatever action it wants, to have to the cell to do. It makes a message, sends a message from the DNA out of the nucleus into the cytoplasm, goes to the ribosome. Ribosomes do the same thing in eukaryotic cells as they do in prokaryotic cells that make proteins. That message comes out of the out of the nucleus from the DNA. The ribosome reads the message and makes a protein that the DNA tells it to make. And that's basically this the how we work in a very simple nutshell. But in eukaryotic cells, there's lots and lots and lots of other organelles in the cytoplasm that participate in making the cell work right, that participate in basically carrying out the will of the DNA, of doing what the DNA wants it to do. So these organelles, I've got them listed here, but they are the cytoplasm, the nucleoplasm, the nucleus, the nucleolus, the ribosome, endoplasmic reticulum, Golgi apparatus, mitochondrion lysosomes and vacuoles. And in eukaryotic cells together, these all basically function together to make the cell work and to make the cell do what the DNA wants it to do. Last thing for today, I want to look at figure 5.3.1 just for a couple of minutes. And this is a figure that looks at the difference basically between a cell with a cell wall and a cell without a cell wall. So let's go to the figure here and take a look at this because in general there are two basic types of eukaryotic cells. So again, eukaryotes are the organisms that are classified into protista, fungi, plantae, and animalia. So there are two basic types of cells. There are eukaryotic cells with cell walls and eukaryotic cells without cell walls. The diagram on the left is a eukaryotic animal cell, and animal cells and people cells do not have cell walls. We have a cell membrane then our cell is done. So we have cell membranes only and then the cell to the right is a eukaryotic plant cell. And plant cells have cell walls as do the organisms that are classified into fungi. On the bottom there right about in the seven o'clock position we can see the cell membrane. So that's the outermost layer of the cell itself. Then for plant cells we have the cell wall those are those two peeled back layers. Some plants have one cell wall, some plants have two. But either way, that layer immediately outside the cell membrane is called the cell wall. Again, it just provides extra structural support and protection for the individual cell. So there are these two basic cell types but then if we look on the inside I'm not going to go over all these today but we will as we go through this but as we go as we look at these you can see that both cells have basically the same types of organelles in them. They both have endoplasmic reticulum there right outside of the nucleus. They both have a nucleus. They both have a nucleolus in the nucleus and, of course, the DNA is in the nucleus for both types of cells. They have the cytoplasm. They have organelles called lysosomes. The Golgi apparatus is another organelle there, etc. But basically I just I wanted you to see the the commonalities that we have between the two different types of eukaryotic cells as well as the differences between the two.