Prokaryotic & Eukaryotic Cells - Online Tutor, Practice Problems & Exam Prep

Prokaryotic cells, including bacteria and archaea, lack a nucleus and membrane-bound organelles, featuring circular DNA located in a nucleoid. They are typically unicellular and smaller, dividing through binary fission. In contrast, eukaryotic cells possess a nucleus, linear DNA, and various organelles, allowing for greater complexity. Eukaryotic cells can be unicellular or multicellular and divide via mitosis and cytokinesis. Both cell types share essential biomolecules and a cell membrane, highlighting their fundamental similarities despite significant structural differences.

Prokaryotic & Eukaryotic Cells

In this video, we're going to talk about prokaryotic and eukaryotic cells. Prokaryotic and eukaryotic are actually the broadest and the most distinct groupings of all life. And the reason for this is because prokaryotic cells actually include 2 different domains of life. It includes both domain bacteria, and it also includes domain Archaea as well. And so, both bacteria and archaea are considered prokaryotic. Now prokaryotic cells specifically do not have an organelle called a nucleus, and so prokaryotic cells do not have a nucleus. Whereas, eukaryotic cells, on the other hand, these are cells that do have a nucleus along with other membrane-bound organelles as well. And so what you'll notice is in prokaryotic and eukaryotic, comparing the two words, they both have this karyo root, and the karyo root is actually referring to the kernel, and it's referring to the kernel of the cell, which is the nucleus. And so karyo is referring to the nucleus, and both, the karyo root is found in both of these words. So both of them are referring to the nucleus. And really what's different are the roots here pro and you as we, kind of highlighted up above. Pro and you is what makes these two words different from each other. So we focus on these roots so we can better understand the meaning of prokaryotic and eukaryotic. And so pro is a root that means before. And so if you put it together, you get pro or before the kernel or the nucleus, so before the nucleus. Before the nucleus is pretty much referring to not having the nucleus because it's before the nucleus. And the u prefix actually means good. And so, putting this together with karyo, you get good nucleus, and that means that it does have a good nucleus or just the nucleus. And so hopefully that can help you distinguish between prokaryotic and eukaryotic a little bit better.

So down below, we're going to take a look at this table here of prokaryotic and eukaryotic cells. So, notice that the table has these column headers that are the domains of life, the cell type, the nucleus, organelles, cell size, and cellularity. And so, of course, for the domains of life, we know that there are 3 domains of life. There are, domain bacteria, domain archaea, and domain eukarya. Now both bacteria and archaea are, collectively, going to be the same cell type of prokaryotic. And this is because, in terms of the nucleus, both bacteria and archaea, they do not have a nucleus, which means that the nucleus is absent. Now on the other hand, of course, Eukarya is going to be eukaryotic cells, and eukaryotic cells specifically do have a nucleus. So here we can say that the nucleus is present. Now in terms of other membrane-bound organelles, prokaryotic cells, including bacteria and archaea, they do not have membrane-bound organelles, so they will be both, absent here. But, of course, in eukaryotic cells, organelles are going to be present. And moving forward in our course, we'll talk about a lot of these different types of organelles found in eukaryotic cells. Now once again, in terms of cell size, it's really important to note that prokaryotic cells are significantly smaller than eukaryotic cells, which are significantly larger. And so you can see here that, prokaryotic cells, they can range in size, of course, but, they're going to be about 1µm here in diameter. Whereas, eukaryotic cells, which can also range in their sizes, are going to be much larger on average. So here we have 100µm. So you can see, that eukaryotic cells can be, up to a 100 times larger than, prokaryotic cells in some cases. Now in terms of cellularity, it's important to note that prokaryotic cells, including bacteria and archaea, are actually unicellular, meaning that they're only made up of 1 single cell since uni means 1 or singular. Whereas, of course, eukaryotic cells, they can either be unicellular or single-celled or they can be multicellular. And so the multicellular organisms that you're aware of are all going to be eukaryotic, and this is, of course, where humans fall. Humans are multicellular. And so this here, concludes our introduction to prokaryotic and eukaryotic cells, and we'll be able to continue to talk more and more about the differences between the two as we move forward in our course. So I'll see you all in our next video.

Which domains of life are classified as prokaryotes?

• A. Bacteria & Eukarya.
• B. Archaea & Fungi.
• C. Bacteria & Archaea.
• D. Bacteria & Protista.

Features of Bacterial Cells

In this video, we're going to talk about some features of bacterial cells, which we know are prokaryotic cells that do not have a nucleus. Now bacteria are actually the most abundant and the most diverse organisms on Earth, and that's because bacteria are the most ancient organisms on Earth. They're the ones that have been around the longest. Now, bacterial DNA is specifically circular in its shape, and again, because bacteria are prokaryotic and they do not have a nucleus, the circular DNA is going to be found in a region that's called the nucleoid. And so the nucleoid is just the name of the specific region where the bacteria's circular DNA can be found. Now bacteria, like all cells, have structures that are called ribosomes, ribosomes. And ribosomes, we'll get to talk more about these later in our course, but, really, what you need to know is that ribosomes are found in every single cell. And ribosomes are specifically used for building proteins. Now once again, all cells have ribosomes including bacteria, but bacteria, specifically have really, really small ribosomes that we call 70s ribosomes. And the s here is something that we're not going to worry about in our course. It's just a unit, that's referring to the size here of the ribosome, and the 70 here is just, the number that goes along with the unit. Now bacteria, they have really small ribosomes, and when bacteria divide or multiply into more cells, they divide by a process that's known as binary fission. And so binary fission is a simple process in, with respect to how eukaryotic cells divide, which is a much more complex process. So let's take a look at our image down below so that we can clear some of these things up. So notice that we're showing you the bacterial cell here, and notice that the DNA that we see, right here, this, blue circle, represents the circular DNA that bacteria have. And the circular DNA is found in the region called the nucleoid. And so once again, the nucleoid is just the region where the circular DNA can be found within bacteria. Now also notice that throughout the cell, we have all of these orange dots and these orange dots represent ribosomes. So notice that we're zooming in here to one of these orange dots And, ribosomes, again, we'll talk more about them later in our course, but basically they are specific for building proteins, and so all cells have ribosomes. But once again, bacteria, they have really really small ribosomes that we call 70s ribosomes. And so this here is representing a 70s ribosome, a small ribosome that, bacteria cells have. And so this here concludes our introduction to the features of bacterial cells, and we'll be able to compare this to features of eukaryotic cells as we move forward in our course. So I'll see you all in our next video.

In bacteria, DNA will be found in _______________.

• A. A membrane-enclosed nucleus.
• B. Mitochondria.
• C. The nucleoid.
• D. Ribosomes.

Features of Eukaryotic Cells

So now that we've talked about some features of prokaryotic cells in our last lesson video, in this video we're going to talk about some features of Eukaryotic Cells. Now, Eukaryotic Cells, unlike prokaryotic cells, actually contain several membrane-bound organelles, including a nucleus. Eukaryotic cells have a nucleus, unlike prokaryotic cells that do not have a nucleus. Eukaryotic DNA is actually linear in its shape, unlike prokaryotic DNA, which is circular in shape. Eukaryotic DNA is found inside of the nucleus it contains. Whereas prokaryotic cells do not have a nucleus, so their DNA is not found inside of a nucleus. Instead, recall that prokaryotic cells, their DNA is found inside of the nucleoid. So, don't confuse the nucleus with the nucleoid.

Also, recall from our last lesson video that all cells have structures called ribosomes that make proteins. We'll talk more about ribosomes later in our course, but we know all cells have ribosomes. Recall from our last lesson, prokaryotic cells have really small 70S ribosomes. But eukaryotic cells, or eukaryotes, have large ribosomes that we call 80S ribosomes, and they are larger.

Eukaryotic cells, instead of dividing by binary fission like prokaryotic cells, divide by a process called mitosis and cytokinesis. We'll talk more about mitosis and cytokinesis later in our course. Eukaryotic cells divide by this more complicated process. If we take a look at our image of a eukaryotic cell, notice the many membrane-bound organelles inside the eukaryotic cells; there's a lot more going on inside a eukaryotic cell than a prokaryotic cell. Eukaryotic cells are much larger and can fit many more organelles.

Notice that eukaryotic cells have a nucleus, represented by the circle you see here. Inside the nucleus, you'll find the cell's DNA, which is linear. And these little blue circles throughout represent ribosomes. Zooming into one of these blue circles, it represents a eukaryotic ribosome, which is quite large, and is known as an 80S ribosome. The 'S' is an abbreviation for 'Svedberg unit,' a term we are not really discussing in this course.

This introduction to some of the features of eukaryotic cells concludes our lesson for now. As we move forward in our course, we'll be able to discuss more about these cells. I'll see you all in our next video.

Which organelle packages the genetic/hereditary material in eukaryotes but not in prokaryotic cells?

• A. Nucleus.
• B. Mitochondria.
• C. Chloroplasts.
• D. Nucleolus.

Recap: Prokaryotic vs. Eukaryotic Cells

In this video, we're going to do a recap of prokaryotic versus eukaryotic cells. And so notice down below we have this chart, and the chart is broken up into 3 different sections. We've got the left section over here, which is all about prokaryotic cells. Then we have the right section over here in green, which is all about eukaryotic cells. And then in the middle here, we have features of both prokaryotic and eukaryotic cells. And so what you'll notice through the numbering that we have over here and over there is that prokaryotic and eukaryotic cells really have 8 key differences, and so we're going to go through the differences first and then we'll wrap up talking about the similarities. So the first and major key difference between prokaryotic and eukaryotic cells is that prokaryotic cells, once again, have no nucleus, whereas eukaryotic cells do have a nucleus. Now also their size is really different, so prokaryotic cells tend to be much smaller, only somewhere between 1 to 10 micrometers, whereas eukaryotic cells, on the other hand, are much larger, and they can be between 10 to 100 micrometers on average, and so that's significantly larger. This means that prokaryotic cells, because they're smaller, are going to be less complex, whereas eukaryotic cells that are larger, are going to be more complex. Now, prokaryotic cells are only going to be unicellular, made up of only one single cell. Whereas, eukaryotic cells, on the other hand, can either be unicellular or they can be multicellular as well. So all multicellular organisms are going to be eukaryotic. Now in terms of the DNA, prokaryotic cells have circular DNA in shape, whereas eukaryotic cells, on the other hand, have DNA that is linear in its shape. Now prokaryotic cells have absolutely no membrane-bound organelles, whereas eukaryotic cells do have membrane-bound organelles. Now in terms of the type of cell division, prokaryotic cells divide by a process called binary fission, which is much simpler than the process that eukaryotic cells divide by, and that is going to be mitosis and cytokinesis. And so, we'll talk more about mitosis and cytokinesis later in our course in a different video. And then last but not least, prokaryotic cells have very small ribosomes that we call 70S ribosomes, where the 70 here implies the size here, that they're smaller. Whereas, eukaryotic cells, they have larger 80S ribosomes, so the 80 here is larger than 70, and that's why eukaryotic cells have larger ribosomes. Now those are the 8 key differences between prokaryotic and eukaryotic cells, but once again, they do have some similarities that we have here in the middle. And so both prokaryotic and eukaryotic cells are going to have a cell membrane. All cells have a cell membrane, and we'll get to talk more about the cell membrane in a different part of our course. Now, also, both prokaryotic and eukaryotic cells contain the major biomolecules that we talked about in some of our previous lesson videos, including carbohydrates, proteins, nucleic acids, and lipids. So both prokaryotic and eukaryotic cells take advantage of these major biomolecules here. And so this here really concludes our recap of prokaryotic and eukaryotic cells, and we'll be able to apply the concepts that we've learned here as we move forward through our course. So I'll see you all in our next video.

Which of the following is/are a primary difference(s) between all prokaryotes and eukaryotic cells?

• A. Prokaryotes have DNA that floats freely in the cytoplasm.
• B. Prokaryotes are significantly smaller than eukaryotic cells.
• C. Prokaryotes do not have ribosomes like eukaryotic cells.
• D. a and b.
• E. a, b, and c

Which of the following is not a common feature shared by all types of cells?

• A. Contains DNA as the genetic material.
• B. Contains a protective cell wall or cell membrane.
• C. Contains a fluid-like portion called the cytoplasm.
• D. Contains a nucleus that stores the genetic material.

You isolate a cell with the following characteristics: (1) no nucleus, (2) a cell wall, and the cell is (3) 2 μm in size. This cell could be a/an:

• A. Bacterium.
• B. Plant cell.
• C. Animal cell.
• D. Bacterial cell or a plant cell.
• E. Plant cell or an animal cell.

Here’s what students ask on this topic:

What are the main differences between prokaryotic and eukaryotic cells?

Prokaryotic cells, such as bacteria and archaea, lack a nucleus and membrane-bound organelles. Their DNA is circular and located in a region called the nucleoid. They are typically unicellular and smaller, ranging from 1 to 10 micrometers, and divide through binary fission. In contrast, eukaryotic cells have a nucleus, linear DNA, and various organelles, allowing for greater complexity. Eukaryotic cells can be unicellular or multicellular and are larger, ranging from 10 to 100 micrometers. They divide via mitosis and cytokinesis. Both cell types share essential biomolecules and a cell membrane, highlighting their fundamental biological functions.

How do prokaryotic cells divide?

Prokaryotic cells divide through a process called binary fission. In binary fission, the cell's circular DNA replicates, and the cell grows in size. The DNA copies move to opposite ends of the cell, and the cell membrane pinches inwards, eventually splitting the cell into two genetically identical daughter cells. This process is simpler and faster than the division process in eukaryotic cells, which involves mitosis and cytokinesis.

What are the key features of bacterial cells?

Bacterial cells, which are prokaryotic, lack a nucleus and have circular DNA located in a region called the nucleoid. They possess small ribosomes (70S) for protein synthesis. Bacteria are unicellular and divide by binary fission. They are the most abundant and diverse organisms on Earth, partly due to their ancient origins. Bacterial cells also have a cell membrane and may have additional structures like cell walls, flagella, and pili for movement and attachment.

What are the similarities between prokaryotic and eukaryotic cells?

Despite their differences, prokaryotic and eukaryotic cells share several similarities. Both cell types have a cell membrane that regulates the entry and exit of substances. They contain essential biomolecules such as carbohydrates, proteins, nucleic acids, and lipids. Additionally, both types of cells have ribosomes for protein synthesis, although prokaryotic ribosomes are smaller (70S) compared to eukaryotic ribosomes (80S). These shared features highlight their fundamental biological functions and evolutionary connections.

How do eukaryotic cells divide?

Eukaryotic cells divide through a more complex process involving mitosis and cytokinesis. During mitosis, the cell's linear DNA is replicated and evenly distributed into two daughter nuclei. This process includes several stages: prophase, metaphase, anaphase, and telophase. Following mitosis, cytokinesis occurs, where the cell's cytoplasm divides, resulting in two genetically identical daughter cells. This division process allows for growth, development, and tissue repair in multicellular organisms.