Introduction to Cell Division: Study with Video Lessons, Practice Problems & Examples

Cell division is crucial for reproduction, growth, and tissue repair. It includes three main types: binary fission, mitosis, and meiosis. Binary fission occurs in prokaryotic cells, while mitosis and meiosis are eukaryotic processes. Mitosis produces diploid somatic cells, essential for growth, while meiosis generates haploid gametes, promoting genetic diversity. Understanding these processes is vital for grasping concepts like the life cycle, genetic variation, and cellular organization. Each daughter cell receives a copy of DNA, ensuring continuity in genetic information.

Introduction to Cell Division

In this video, we're going to begin our introduction to cell division. Now, cell division can be defined as the process of a single parent cell dividing or splitting into greater than or equal to 2 or more daughter cells. And so, this term "daughter cells," you'll hear your professor use it occasionally from time to time, and you'll see it throughout your textbooks as well. And so, this term "daughter cells" is really just referring to the cells that result from cell division or cell splitting. Now, moving forward in our course, we're going to talk about 3 main types of cell division, and we have these 3 main types numbered 1, 2, and 3 down below. And of course, the numbers in our text correspond with the numbers that you see down below throughout our image. And so, the first main type of cell division that we're going to introduce is called Binary Fission. And really the most important thing that you should know about binary fission is that this is a type of prokaryotic cell division. And so only prokaryotic cells like bacteria or archaea are going to divide by binary fission. But eukaryotic cells that do have a nucleus, they do not divide by binary fission. And so, let's take a look at our image down below over here on the left-hand side to clear some of this up. And so notice that we're showing you an image of binary fission. And once again, binary fission is a type of cell division that only occurs in prokaryotic cells like bacteria or archaea that do not have a nucleus. And so notice here we're showing you a single parent prokaryotic cell that does not have a nucleus, and notice that its DNA is just floating on the inside of the cell in the cytoplasm in a region called the nucleoid, which, that is review from our older lesson videos. But, the big point here of binary fission is that it starts with a prokaryotic cell, and notice that by the end of the process, there are 2 cells, 2 prokaryotic cells. And so these 2 cells are termed the daughter cells since these are the cells that result from the cell division. And notice that each daughter cell down below has a copy of the DNA which is in green, and that means that this original copy of the DNA is going to have to get replicated or duplicated at some point in this process, but we'll talk more about DNA replication later in our course. And again, the biggest takeaway for binary fission is that this is how prokaryotic cells divide. Now, the other two types of cell division that we're going to introduce, are types of eukaryotic cell division. And so we're going to look at them specifically as they apply to the human life cycle. And so the second type of cell division that we're going to talk about is mitosis, whereas the third type of cell division that we're going to talk about is meiosis. Now, I'll admit, at first glance, mitosis and meiosis, they sound really, really similar. And in fact, it turns out not only do they sound similar, but they also have a lot of similarities. But mitosis and meiosis are different processes. And so moving forward in our course, it's going to be very important for you guys to be able to distinguish between mitosis and meiosis. Now moving forward in our course, we're mainly going to try to break down mitosis first, but then after we're done breaking down mitosis, then we'll switch over to discuss meiosis. Now just to give you a little bit of background information about mitosis and meiosis, mitosis again is a eukaryotic cell division that is going to produce what are known as somatic cells. And somatic cells are really just body cells that do not get passed down to the next generation. And so somatic cells or body cells would include cells like our heart cells, our liver cells, and our skin cells. Now human somatic cells are what are known as diploid cells. And we'll talk more about diploid later in our course, but really what diploid means is that there are going to be 2 copies of every chromosome inside of these cells. And so diploid is going to be symbolized using a symbol called 2n. And so anytime you see n=2, you know that it represents a diploid cell. And again, you can think, the n here represents the number of copies of chromosomes, and of course, diploid cells have 2 copies of every chromosome. Now meiosis, on the other hand, the third type of cell division is also a eukaryotic cell division. But instead of producing somatic cells like mitosis does, meiosis produces what are known as gametes. And gametes are really just the fancy scientific name for sex cells such as the sperm in males and the eggs in females. Now human gametes, on the other hand, unlike human somatic cells, they are not diploid and so they don't have 2 copies of every chromosome. Instead, human gametes are what are known as haploid cells. And haploid kinda sounds like half, so they have half the number of chromosomes. So instead of having 2 copies of every chromosome, they're only going to have one copy of every chromosome. And again, if this, diploid and haploid concept was a little bit difficult for you to understand, we're going to talk more about it later in our course. So this is more so of a foreshadowing for you guys to get to understand these terms a little bit early. And so let's take a look at our image down below over here on the right-hand side to better distinguish mitosis and meiosis. And so what's important to note again is that this image is showing the human life cycle. So what you'll notice here at the top are 2 adults. Notice that there's a male, and there is a female. And the males produce what are known, produce gametes, that are called sperm cells. And so, this process is going to be meiosis. Meiosis is the process that is going to produce the sex cells, the gametes, such as the sperm and the egg. And the egg over here is, the sex cell, or the gamete of the female. Now notice that these gametes here are haploid. They have the n symbol here which represents haploid. So that means that they have half the number of chromosomes. They only have one copy of every chromosome, And that's because, during sexual reproduction, the sperm and the egg gametes are going to merge together in a process that's called fertilization. So you can see the sperm here merging with the egg. And they each have half the number of chromosomes. They each have one copy of every chromosome. So when they merge together, the resulting cell which is called a zygote ends up having 2 copies of every chromosome, so it becomes a diploid cell. And so the zygote here is a diploid cell, the very first cell of a human. And so this zygote ends up growing and growing and growing into many trillions and trillions of cells through the process called mitosis. And mitosis is what

Which of the following statements about cell division is correct?

• A. It is the process by which one parent cell divide into 2 daughter cells.
• B. It is an unnecessary process once an organism reaches maturity.
• C. It is the process by which two sex cells fuse.
• D. It occurs in 2 stages of mitosis then meiosis in all types of cells.

Which one of the following best defines binary fission?

• A. The process by which one cell splits into two cells.
• B. The process by which one cell splits into four cells.
• C. The process by which two cells combine to create a new cell.
• D. The process by which gametes are created.

Asexual vs. Sexual Reproduction

In this video, we're going to distinguish between asexual and sexual reproduction. All living organisms must reproduce or generate more living offspring via one of two types of reproduction that we have numbered below, number 1 and number 2. The numbers that you see here in the text correspond with the numbers that you see down below in the image.

Now, the first main type of reproduction is asexual reproduction. Asexual reproduction, of course, means that there's no sexual activity involved in the reproduction. And if you think about it, if there's no sexual activity involved, that means that there's only one single parent involved in asexual reproduction. And if there's only one single parent involved in asexual reproduction, that means that there's only one single source of the DNA from that one single parent. And if there's only one single source of the DNA, then that means that the offspring are all going to be genetically identical to one another because they are all going to be resulting from this single parent, with only one source of DNA.

On the other hand, the second type of reproduction is sexual reproduction. Sexual reproduction, as its name implies, means that sexual activity is involved. And, of course, sexual activity means that there are going to be two parents involved in this type of reproduction instead of just one parent. And if there are two parents involved, that means that there are two sources of the DNA. One source of the DNA would be the father. The other source of the DNA would be the mother. Typically, with sexual reproduction, the father and the mother do not have identical DNA. Their DNA is going to be different from one another. And so we have two different sources of DNA, and that's going to result in offspring that are genetically diverse from one another. They will not be genetically identical under most circumstances when it comes to sexual reproduction.

Now let's take a look at our image down below to further distinguish between asexual and sexual reproduction. Over here on the left-hand side, these two images for binary fission and mitosis are falling under the category of asexual reproduction because they do not involve any sexual activity. And again, that means that there's only one parent involved. And so notice that for both binary fission and mitosis, the very beginning starts with just one single parent cell. And at the end of the process, it results in two daughter cells for both. But because there's only one single parent cell involved in both binary fission and mitosis, they're both forms of asexual reproduction. And because there's only one single parent cell, there's only one source of DNA and the cells that result are going to be genetically identical to each other. For both, again, binary fission And, for the process of mitosis, two daughter cells that are resulting are going to be genetically identical.

This is not the case with this right side of the image over here, which is showing you sexual reproduction. And so sexual reproduction, of course, is going to involve two parents instead of one. So you can see the male parent over here and the female parent over here. And it's the process of meiosis, not to be confused with mitosis, that forms the gametes or the sex cells. And because meiosis forms the sex cells, meiosis is more closely linked to sexual reproduction since, again, it forms the sex cells, the sperm, and the egg. And of course, the sperm and the egg are going to fuse together to form the zygote, which ends up resulting in the individual, the offspring if you will.

What's important to note about sexual reproduction is that it's going to create genetically diverse offspring. We'll get to talk more and more about these ideas as we move forward in our course. But for now, this here concludes our introduction to the difference between asexual and sexual reproduction, and we'll be able to get some practice as we move forward.

So I'll see you all in our next video.

Asexual reproduction differs from sexual reproduction in that:

• A. Asexual reproduction produces genetically diverse offspring.
• B. Asexual reproduction occurs only in bacteria.
• C. Asexual reproduction produces offspring that are virtually identical.
• D. Asexual reproduction does not occur in animals.

Importance of Cell Division

So now that we've introduced the 3 main types of cell division, binary fission, mitosis, and meiosis, in this video we're going to talk about the importance of cell division. Cell division is an important process for reproduction, making more life, fetal development, or growth, allowing a single-celled zygote to grow into a baby and allowing the baby to grow into a fully mature adult through the process of cell division. Cell division is also an important process for tissue repair. If you get a cut or something similar, that tissue is going to die when you get the cut. The dead tissue needs to be replaced and the replacement cells come from the process of cell division. Below here on the left-hand side, we're showing you an image of asexual reproduction, basically showing you how a single cell can divide to create 2 cells, and you can see the cell here is in the process of dividing.

Some cells rely on cell division for reproduction purposes since many organisms are single-celled and the only way that they can create more life is through cell division. Fetus development is also a critical component of cell division. Allowing a single-celled zygote to grow into a fetus and allowing the fetus to grow and develop into a baby, then the baby to grow into a toddler and so on until the full adult is formed. This is very important, and cell division plays a big role in the process of fetal development. Here in this image, it's showing you a single-celled zygote and how it can divide to form 2 cells, and then each of those can divide to form 4 cells and so on until there are trillions of cells allowing for the fetus to develop.

Once again, cell division is very important for tissue repair and renewal. This is showing you an image of some cells that are dividing to help repair a specific tissue. Cell division is very important for reproduction, fetal development, and tissue repair, which are the main components that cell division is important for. But before a single cell divides to create 2 cells, each of those cells needs to have a copy of the DNA. That means that before any cell can divide, it must first replicate or duplicate or make an extra copy of the DNA so that each of the daughter cells that result can get their own copy of the DNA. The organization of the DNA is going to be a very important component for understanding cell division and how it works.

Moving forward in our course, we're going to start to talk about the organization of DNA inside of the cell. I'll see you all in our next video.

Here’s what students ask on this topic:

What are the main differences between mitosis and meiosis?

Mitosis and meiosis are both types of eukaryotic cell division, but they serve different purposes and have distinct processes. Mitosis results in two diploid somatic cells that are genetically identical to the parent cell, essential for growth, development, and tissue repair. It involves one division cycle. Meiosis, on the other hand, produces four haploid gametes (sperm or eggs) that are genetically diverse, promoting genetic variation in sexual reproduction. Meiosis involves two division cycles: meiosis I and meiosis II. The key differences lie in their outcomes (diploid vs. haploid cells) and their roles in the organism (growth vs. reproduction).

How does binary fission differ from mitosis?

Binary fission and mitosis are both processes of cell division, but they occur in different types of cells. Binary fission is a form of asexual reproduction in prokaryotic cells, such as bacteria and archaea, where a single cell divides into two genetically identical daughter cells. It involves the replication of the cell's DNA, which is then distributed into two new cells. Mitosis, on the other hand, occurs in eukaryotic cells and involves a more complex process of nuclear division followed by cytokinesis, resulting in two diploid somatic cells. Mitosis is crucial for growth, development, and tissue repair in multicellular organisms.

Why is cell division important for tissue repair?

Cell division is crucial for tissue repair because it allows the body to replace damaged or dead cells with new ones. When you get a cut or injury, the cells at the site of the damage die and need to be replaced to restore the tissue's function. Through the process of mitosis, new cells are generated to replace the lost or damaged cells, ensuring that the tissue can heal and regain its normal structure and function. This continuous process of cell division is essential for maintaining the integrity and health of tissues throughout an organism's life.

What role does meiosis play in genetic diversity?

Meiosis plays a critical role in genetic diversity by producing haploid gametes (sperm and eggs) that have unique combinations of genes. During meiosis, homologous chromosomes undergo recombination or crossing over, where segments of DNA are exchanged between paired chromosomes. This process creates new combinations of alleles, contributing to genetic variation. Additionally, the random assortment of chromosomes during meiosis I ensures that each gamete has a different set of chromosomes. When gametes from two parents fuse during fertilization, the resulting offspring have a unique genetic makeup, promoting diversity within a population.

How does the process of fertilization relate to cell division?

Fertilization is the process where a sperm cell from a male merges with an egg cell from a female, resulting in the formation of a zygote. This zygote is a diploid cell, containing two sets of chromosomes, one from each parent. Following fertilization, the zygote undergoes multiple rounds of mitosis, a type of cell division, to grow and develop into a multicellular organism. Mitosis ensures that each new cell has the same genetic information as the original zygote, allowing the organism to develop from a single cell into a complex structure with trillions of cells.