What Is Mitosis? A Complete Guide to Mitotic Cell Division

If you’re studying biology, the concept of mitosis is pretty unavoidable. Mitosis is part of the cell cycle, and studying how cells work makes up a huge portion of any biology class. It’s safe to say you’re going to need some working knowledge of mitosis if you’re looking to breeze through any biology-related course or exam. 

Here’s what we’re going to cover in this article so you’re up to speed on the purpose of mitosis, how the process of mitosis works, and why mitosis is important to know about. We will:

• Answer the question, “What is the purpose of mitosis?” (definition and explanation of the importance of mitosis included)
• Description of the 4 phases of mitosis
• Review the similarities and differences between mitosis and meiosis
• Our top three tips for studying and memorizing the stages of mitosis, and
• Three resources for further learning about mitosis!

And, now, let our journey through the world of mitosis begin!

Mitosis Definition

The first thing we need to do is answer the question, “What is mitosis?” In cell biology, mitosis is a part of what is called the cell cycle. The cell cycle, sometimes called the cell-division cycle, is the series of events that occur in a cell that lead to duplication of that cell’s DNA and, ultimately, the creation of new cells. During mitosis, the cell division part of the cell cycle, a single parent cell’s replicated genetic material—called chromosomes—divides to produce two new, genetically-identical daughter cells.

In the cell cycle, the cell’s DNA is replicated in interphase, the phase that precedes mitosis. Mitosis alternates with interphase to make up the cell cycle in its entirety. In fact, a cell cannot begin mitosis until interphase is successfully completed. 

So we’ve explained that mitosis is the part of the cell cycle when cell division occurs, but let’s get a little more detailed than that. During mitosis, one cell divides one time, and the cell that’s being divided is always called the “parent cell.” When the process of dividing the parent cell is complete, the result is two “daughter cells.” These cells are called daughter cells because, during mitosis, the genetic material of the parent cell is passed on to each new daughter cell. 

But it’s important to note that, in the type of cells that undergo mitosis, the genetic material of the cell is contained within the cell’s nucleus. So, while mitosis is often referred to as “cell division,” mitosis is technically the division of a cell’s nucleus into two new, identical nuclei. 

What Types of Cells Undergo Mitosis? 

You may have heard about two types of cells: eukaryotic (animal) cells, and prokaryotic (plant) cells. Both types of cells undergo cell division, but only eukaryotic cells experience cell division through mitosis. In fact, all eukaryotic cells can engage in mitosis. 

Mitosis happens exclusively in eukaryotic cells because this type of cell has a nucleus. The nucleus of a cell contains its genetic matter, and this is what is passed to the new “daughter” cells in the process of mitosis, or cell division. In order to replicate the genetic material, mitosis has to occur in cells that have a nucleus. 

2 Reasons Why Cells Divide (and Why Cell Division Is so Important)

Answering the question, “Why do cells divide?” pretty much also answers the question, “Why is mitosis important?” The process of mitotic cell division in eukaryotic cells is important for two main reasons: because cell division creates new cells that keep eukaryotic organisms thriving, and because cell division passes a consistent genetic identity to a new generation of cells. 

First, the division part of the cell cycle—mitosis—is so important because the parent cell passes its genetic information to its offspring cells (sometimes called “daughter” cells) during this type of cell division. If cell division doesn’t occur, new cells can’t be created. And it’s important for new cells to be created in eukaryotic organisms because . . . cells get worn out and die! The dead cells need to be replaced with new cells so the organism can continue growing. 

Second, the process of mitosis is so important because parent and daughter cells in certain types of organisms must be identical in order for the organism to survive. When mitosis occurs successfully, two new cells with the same genetic composition and an identical chromosome set to the previous generation are created. If there’s an error during mitosis, harmful conditions can develop, like cancer or hemophilia. 

When Does Mitosis Occur in the Cell Cycle? 

Mitosis is really important, but it’s actually only one part of the cell cycle. A period called interphase precedes mitosis in the cell cycle, and interphase and mitosis alternate as the cell cycle occurs over and over. So, mitosis is the second or concluding part of the cell cycle, and mitosis cannot start until interphase has been successfully completed. 

During interphase, the cell grows and develops the proteins needed for cell division. In the middle of the interphase period, the cell duplicates its chromosomes. Once the chromosomes have been duplicated and all other conditions are ideal in the cell, the first phase of mitosis can begin!

The 4 Phases of Mitosis, Explained

We have a much longer article that covers the four phases of mitosis in more detail, but we do want to give you an overview of what the four phases of mitosis are and what happens during each phase here. If you’re looking for a deep dive into the four phases of mitosis, take a look at our article, “A Detailed Breakdown of the 4 Phases of Mitosis”!

Mitosis is a process that happens in phases that always occur in the same order and accomplish the same tasks (unless something goes wrong!). The four phases of mitosis are prophase (P), metaphase (M), anaphase (A), and telophase (T). Each of these phases helps achieve the purpose of mitosis by moving the process of cell division and reproduction along. Without the proper completion of each of the four phases, cell division wouldn’t happen the way it’s supposed to. 

We’ll quickly breakdown each phase of mitosis for you next!

Phase 1: Prophase and Prometaphase

During prophase, the first phase of mitosis, the chromatins inside the cell’s nucleus begin condensing into chromosomes. The protective membrane surrounding the cell’s nucleus, called the nuclear envelope or membrane, also begins to break down. 

As the chromosomes condense inside the nucleus and the nuclear membrane disintegrates, centrioles outside of the nucleus start moving toward opposite sides of the cell and form the mitotic spindle, which is made up of fibers called microtubules. The mitotic spindle stretches from one side of the cell to the other, suspended between those centrioles that moved away from each other. 

Phase 2: Metaphase

Metaphase is the second phase of mitosis. During metaphase, spindle fibers attach to the centromere of each pair of sister chromatids. The sister chromatids also move into the middle of the cell and line up along an invisible line, called the metaphase plate. These spindle fibers prepare the sister chromatids to separate properly in the next phase of mitosis. 

Phase 3: Anaphase

Anaphase is the third phase of mitosis, and this is when cell division really begins. During anaphase, the spindle fibers attached to the sister chromatids start shortening, which pulls the sister chromatids apart down the middle toward opposite sides of the cell. By the end of anaphase, each side of the cell has a complete, identical set of chromosomes. 

Phase 4: Telophase

Finally, we have telophase: the fourth and final phase of mitosis. In telophase, the separated chromosomes start to unfold and form chromatin. The spindle also disintegrates, and a new nuclear envelope forms around the two new sets of chromosomes. These two new sets of chromosomes make up two nuclei, which have received genetic information from their parent cell. 

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Mitosis Versus Meiosis: The Similarities and Differences

Mitosis, meiosis. You probably know that both of these processes have something to do with cells. But what’s the difference between the function of mitosis and the function of meiosis, and why do you need to know the difference? 

—To understand how mitosis and meiosis are related, the first thing you need to know is that mitosis isn’t the only type of cell division that can occur. Meiosis is also a form of cell division and reproduction! But while mitosis results in two identical daughter cells, meiosis results in four sex cells. That’s right—meiosis is the process of cell division and reproduction that occurs in organisms that reproduce sexually. 

Here are the key differences between mitosis and meiosis as processes of cell division and reproduction: 

That’s a lot of differences, right? But there are also several similarities between the processes of mitosis and meiosis. Here they are: 

• Both mitosis and meiosis begin with a diploid parent cell, or a parent cell with two sets of chromosomes

• Mitosis and meiosis go through the same phases, in the same order—prophase, metaphase, anaphase, and telophase—but the phases occur only once during mitosis and twice during meiosis

• Both mitosis and meiosis end with cytokinesis, the cytoplasmic division of a eukaryotic cell into two daughter cells

In general, you want to try to remember the two main differences between mitosis and meiosis: meiosis involves two cell divisions, while mitosis only involves one, and meiosis gives rise to the production of germ cells, while mitosis gives rise to the production of somatic cells. 

Now you should be able to come up with answers to the questions, “What is the purpose of mitosis?” and, “What is the purpose of meiosis?” all on your own! Next, we’ll tell you about our top three tips for studying and memorizing the details of mitosis. 

Our Top 3 Tips for Studying and Memorizing the Details of Mitosis

Now, learning cell biology is essentially a gargantuan effort to remember a lot of stuff about a lot of things, so maybe you’re wondering how you’re going to remember what the stages of mitosis are, the order of the phases, what happens in each phase . . . the list could probably go on! Fear not: we’ve come up with some strategies that can help you remember some of the most important details about mitosis. Check out our top three tips for studying and memorizing the key details about mitosis below. 

Mnemonic Devices

Mnemonic devices are techniques that people can use to help them remember something. If you need to remember the 4 stages of mitosis in order, try memorizing one of these mnemonic devices: 

Get it? The first letter of each word in the mnemonic devices above corresponds with the first letter of each of the phases of mitosis, plus interphase: 

Adding one of these easy-to-remember phrases to your study arsenal can make remembering the phases of mitosis much easier in a high-pressure situation!

Use the Letters In “Mitosis” and “Meiosis” to Remember the Difference 

If you thought those mnemonic devices were a cheesy way to remember key details about mitosis, just wait: we’ve also got a couple of ways to differentiate between mitosis and meiosis just by using the letters in the words mitosis and meiosis. Here’s an example: 

Mitosis has a “t” in it, so mitosis is going to result in two cells. Here’s a visual: 

The “T” in mitosis = two cells. Just remember that “t,” which should help you remember that mitosis results in two genetically identical daughter cells. 

Now for meiosis—and this one is easier. Ready? Meiosis doesn’t have a “T” in it, so it isn’t going to make two cells. “T” in mitosis = two cells. No “T” in meiosis = not two cells. 

A Different Kind of Mnemonic and A Hand Trick

Maybe you need a trick to remember what happens during each phase of mitosis in addition to remembering what order they go in. Here’s one more trick that takes the first letter of each phase of mitosis and associates it with a word starting with that same letter to describe what happens in the corresponding phase of mitosis: 

Prepare - middle - apart - tear. The idea with this one is to use one word that sort of sums up what happens in each phase of mitosis to trigger your memory about the other details of what happens in that phase. So, for example, if you can remember prophase = prepare, that should set you up to explain how prophase prepares the genetic material in the cell’s nucleus for division by condensing it tightly together. 

If a visual representation of what happens during each phase of mitosis is more helpful to you than another mnemonic device, try memorizing the quick hand trick demonstrated in this YouTube video! You could also combine the descriptive words from the mnemonic above with the hand trick for a double whammy. 

3 Resources for Further Learning About Mitosis

If you need some extra help answering the question, “What is mitosis?” on your own or want to build on your current mitosis definition, check out the three resources below that provide more information about mitosis!

Nature Journal

Maybe you’re feeling pretty ambitious and you want to dive into peer-reviewed, academic research articles on mitosis. One of the best places you can turn for that is Nature, an international science journal, and one of the most reputable in its field. 

If you need to do research on mitosis that’s going to be up to, say, a college professor’s expectations, any search you do in Nature’s archives will get you the kind of sources you need. 

The big drawback of most academic research journals is that the subscription fees are hefty. A one-year subscription to Nature for students is $119. Don’t lose heart, though. A lot of times, schools and universities buy subscriptions to reputable journals, so it’s likely you could access articles or issues on mitosis through your school library’s online databases. If you’re in doubt, just ask a research librarian!

Scitable by Nature Education

If a full-fledged, peer-reviewed scientific journal is a bit much for you at this point, Nature Education provides a tapered down resource for students looking for credible overviews of science-related topics, called Scitable. Scitable focuses specifically on key genetic concepts, so they definitely provide content that covers mitosis. 

When you search a concept on Scitable, the results pop up conveniently categorized based on type of content. So, if you search “mitosis” from the Scitable homepage, you’ll get results categorized as “articles,” “concept pages,” “definitions,” “images,” and “blog posts.” We recommend exploring Scitable on your own, but we’ve also linked to a few resources on mitosis that Scitable provides below: 

• Mitosis definition page
• Concept page explaining replication and distribution of DNA during mitosis
• Video showing a timelapse of mitosis occurring under a light microscope

If you’re looking for a variety of scientist-authored educational resources on mitosis in one place, Scitable is a great place to go. 

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The Amoeba Sisters’ YouTube Videos on Mitosis

If some jazzy music and creative visuals help you get focused to learn something new, try checking out the Amoeba Sisters’ set of YouTube videos on mitosis. Their content is lively, accessible, and relatable, which is always a welcome way to learn more about (or frantically review) science-y things!

The Amoeba Sisters have several videos that will help you answer the question, “What is mitosis?”, but we especially recommend “Mitosis: The Amazing Cell Process that Uses Division to Multiply!” and “Mitosis vs. Meiosis: Side by Side Comparison.” And they don’t just provide video content: if you look right under all of their videos on YouTube, you’ll find that they provide a link to a page with tons of handouts that you can use to study and review what you’ve learned from their videos about mitosis. If you’re still asking yourself, “What is mitosis?”, these videos and handouts can help you answer that question.

One more cool thing about their videos: they update them periodically to ensure their content stays up-to-date with scientific research and what’s being taught in formal education settings pertaining to mitosis, so you know you’re getting credible information.

What’s Next?

Are you still a little confused about what happens during mitosis? Or do you need a more in-depth resource to help you study? Here’s a step-by-step guide to mitosis that breaks every phrase down in detail. Once you read this article, you’ll be on the way to becoming a mitosis expert!

If you think biology is amazing, you might be a good candidate for taking AP Biology classes in high school. Here’s a guide to help you decide if an AP Bio class is right for you. (You can also take a sneak peek at the AP Biology syllabus to give you an inside look at what taking the class would be like!)

Maybe you’re already taking AP or IB Biology and are looking for more study resources. We’ve got you covered there, too. Here’s a complete AP Biology review and a comprehensive list of the best online IB Biology SL/HL study notes, too.