 Here, everybody, Dr. O here. Let's take a little deeper dive into mitosis. We're going to start by looking at the different phases of the entire cell life cycle. So let's start with G0. If a cell is in a resting state and not actively dividing, either because it stopped dividing temporarily or permanently, it's going to be in what's called GO. G1 phase stands for GAP1 phase. This will be the first growth phase in a new cell life cycle. So during G1, this is going to be during interphase when the cell is growing and carrying out its own functions. So G1 might be a very long time, might be forever if a cell is not going to divide, or it might be for a short period of time for cells that divide very quickly. So the biggest variability between one or two or three different types of cells will be how long this G1 phase is. So G1 is GAP1 phase. You see this first bit of growth. But then if a cell is going to divide, it's going to go into S phase. With S phase stands for synthesis phase. This is going to be where the cell replicates its DNA. If one cell with 46 chromosomes is going to divide and form two cells with 46 chromosomes, it has to duplicate its chromosomes at some point. That's what's going to happen here during the S phase. Then we go into G2, or the second GAP phase. This is going to be where the cell continues to prepare for mitosis. And the M phase there is mitosis, prophase, metaphase, anaphase, telophase will happen there, then cytokinesis. Now we have two cells and they will enter the next phase and continue on the cell cycle, which is why it's called that. All right, now let's go and look at the phases of mitosis. I've already mentioned that during interphase, this is before mitosis, it's about 90% of the typical cells' life cycle. The cell is just doing its job. It's not dividing, but it's preparing to divide by doing things I just mentioned, replicating DNA, replicating organelles. But now we're in the M phase, the mitotic phase, and we're going to start with prophase. So prophase is going to be the key thing that happens here is going to be the nuclear envelope breaks down, disintegrates, disappears. So the nucleus disappears so that your cell can get at the DNA and manipulate it. So notice there the first point, chromosomes condense and become visible. Unless a cell's dividing, its chromosomes are not formed. The DNA is going to be chromatin, just real thin DNA spread throughout the nucleus. It clumps together to form chromosomes during mitosis. So that's what the chromosomes have become visible now. Now notice those centrosomes are getting involved. The centriole is the organelle of cell division and the centriole plus these microtubule filaments are going to form this centrosome and they're going to manipulate and grab DNA and move it around. And they're also going to push the other direction to help spread your cell out. All right, so during prophase, the chromosomes have formed to become visible and the nucleus has disappeared. That's going to be the key things. Then we move into prometaphase, which is going to involve, like I said, the central here is the organelles needed for cell division. The centrosome is that the pair of centrioles plus these microtubules. And notice how they're grabbing and manipulating the chromosomes. So prometaphase is this phase period between prophase and metaphase. Key thing happening here is that these centrioles, these centrosomes are getting very, very active. So they're forming this mitotic spindle and they're getting ready to grab that DNA and move it to the center. So that's going to be prometaphase. Metaphase, the key thing that happens here is these chromosomes are all grabbed and they're lined up at the equator or the metaphase played to the cell. So now our nucleus is long gone, our DNA is now being lined up in these chromosomes at the equator of the cell, which prepares us for anaphase. During anaphase, the centrioles and these microtubules are going to pull and they're going to pull this pile of DNA into two smaller piles. So that's going to be the key thing that happens there during anaphase. The chromosomes are all pulled apart as these microtubules contract and shorten. Then we have telaphase, some say telaphase. This is going to be, so notice that our chromosomes have been pulled apart into two piles and they're going to start to just become chromatins. So our chromosomes are going to disappear. The two new nuclei are going to form. So now we're still only one cell, but it's going to have two visible nuclei in it. I always think of the egg with two yolks. So the cell contents, including the nucleus, have divided, but the cell hasn't. And that's going to be as telaphase is finishing up. Cytokinesis is going to take over. And cytokinesis is when we get what's called a cleavage furrow. This band of contractile tissue that's actually made of the microfilament actin, which is the thin filament in regular muscle contractions, is going to contract. And as it contracts, it's going to split that cell into two. Here's how I think of it. You take a balloon that's not full and you twist it and twist it and twist it until two small balloons pop up. It seals those ends. That's kind of what I always think about with cytokinesis. So the cell's going to be pinched in half and now we have two cells. At the end of this time, one of these cells will be a stem cell that can go ahead and do this again and make another cell. That second cell is going to go do its job and replace the old cell that needed to be replaced. And then these cells are going to be in interphase again. And then when they're ready to divide, they'll go back through this whole process again. So that is interphase mitosis, which is prophase, metaphase, anaphase, and telaphase, or telaphase, and then cytokinesis. And that's how our body cells divide. We'll cover meiosis in a separate video. I hope this helps. Have a wonderful day. Be blessed.