 Now, we look at the diagram. This diagram in front of you can show quickly the whole process of mitosis or the division. As you can see in the first diagram A, the cell is present in the interface. The nuclear membrane is complete and now this is the diagram showing the mitosis in animal cell. You can see a nucleus in between, you can see centrosomes, a pair of centrioles present on one side of the nucleus. The diagram B, next one, shows the early prophase. In this diagram, you can see that the chromosomes, they start appearing, they become condensed and we can observe them under a microscope. The spindle fibres are forming. After that, cells enter into the, next we can call it the late prophase. In late prophase, the spindle fibres are formed and the chromosomes start attaching themselves to the spindle fibres. After this, next stage comes the metaphase. In metaphase, cells, chromosomes arrange themselves on the spindle fibres. They are attached to spindle fibres in the, almost in the center. In the next phase, anaphase, the chromosomes starts moving towards the poles of the cell and they are as you can observe. The chromosomes, they are divided from the center and equal number of chromosomes are going on both sides. In the telophase, you can see that the chromosomes reached that center. They started to, started thinning again and the nucleon membrane starts forming. In the next phase, you can see that the cell is divided into two daughter cells. Now we look at these processes, all of these stages in detail. Metaphase results in two cells which are alike, just like each other, by almost every aspect. Mitosis is also called, it's a caryokinesis, you know that caryo is the word used for the nucleus. This is for division of the nucleus. When the mitosis of the caryokinesis completes, then comes the next phase called cytokinesis when cell itself is divided into two. The caryokinesis consists of four phases, prophase, metaphase, anaphase and a telophase. When these four phases complete, prophase, metaphase, anaphase and telophase, then the nucleus is completely divided and then the cell divides itself into two daughter cells. Now cytokinesis is different in animal and plant cells, we will talk about it later. We are talking about the actual mitosis, the caryokinesis, prophase, we are talking about the first phase, the prophase. In the interface, the chromosomes are not visible, we can see only the nucleus because the chromosomes are very thin at that stage. In prophase, chromosomes start condensing, due to the condensation they become appearing under the microscope, prophase. First of all we are talking about prophase. In the interface, chromosomes are very thin and they are not visible under the microscope. But as the prophase starts, the chromosomes start condensing, start thickening, due to this condensation they become visible under the microscope. As we know that cell has passed through a process of DNA synthesis already, so each chromosome at this phase is duplicated, is double and have two parts which are alike called the sister chromatids. If you look at the diagram above, you can see that one chromosome is duplicated and it is looking like there are two. These are actually the replicated or the duplicated chromosomes. Now each chromosome has a central point where we call both of these parts the sister chromatids. They have a central point, the central point here, where both of these sister chromatids are joined together. Then this part is also occupied by a protein called kinetochore. Kinetochore is attached, is actually attached these sister chromatids to each other and later on in the later prophase, when the spindle fibres are formed, kinetochore attaches these sister chromatids to the spindle fibres. In next part, in the prophase, the chromosomes they are condensed, they consist of sister chromatids attached to each other. The centrioles they start moving towards the poles of the cell and they form the spindle fibres, long long fibres which are present for the attachment of chromosomes and their movement. At the end of the polymers, at the end of the prophase, the chromosomes attach themselves with the help of their kinetochores to the spindle fibres. At the end when this is complete, the nuclear membrane starts dissolving and now the nuclear membrane is not present, so the chromatin material is exposed in the nucleoplasm only and they are not surrounded by a membrane, the nuclear membrane disappears. In plant cells, the centrioles are not present and the spindle fibres, they are formed with the help of the components of spindle fibres, the microtubules present inside the cytoplasm which are produced by the endoplasmic reticulum and the colgibodies. Then comes the next phase called metaphase. In metaphase, chromosomes arrange themselves on the equator. As we know that in the prophase, chromosomes they were attached to the spindle fibres with the help of their kinetochores. Now they arrange themselves in almost centre of the cell, we call it equator. So in metaphase, cells arrange themselves in the centre. After metaphase, the next stage comes is called anaphase. In anaphase, the spindle fibres start pulling chromosomes towards the poles. When they apply the pulling forces on the chromosomes, the sister chromatids divide from their kinetochores and they are separated. They divide actually from the centre mirror from which they are, they were attached to each other and the sister chromatids, they are separated and out of each chromosome, one sister chromatid move towards one pole and the other sister chromatid move towards the other pole. This stage is called anaphase. Then these chromosomes keep moving towards the poles in the anaphase and this stage is important and critical because equal number of chromosomes actually in this at this time the sister chromatids should reach each pole to retain the natural chromosome number. If some sister chromatids they do not divide, then the result will be faulty cells and they may be, they may die, they cannot survive. So the anaphase is this phase in which the spindle fibres start pulling the chromosomes towards the poles. Chromosomes are divided at the centre mirror and each sister chromatid move towards one pole. Then comes the next phase called telophase. In telophase the sister chromatids reaches at the pole. At this stage they start decondensing and they start we can say thinning again coming back to their normal position in which they were present before the profile. At this stage we can say the nuclear material, the chromatin material, the chromosomes they start decondensing. So at the end of this stage the nuclear membrane start reforming. When this stage reaches the mitosis or we can say the nuclear division the karyokinesis is complete and then the cell enters into the the next phase called cytokinesis that is division of the whole cell. Now division of the whole cell is different in the animal and the plant cells. We have a look on certain pictures taken from onion cells for the in their prophase, in their metaphase, anaphase and telophase. Let us have a look on these pictures first and then we will talk about the cytokinesis. Here in the diagram you can see in the circle on the top prophase. This is the real picture taken from the microscope. You can see the chromatin material is condensing. On the right down you can see a metaphase the chromosomes are arranged on the equator. In the next picture you can see beautifully placed anaphase in which the chromosomes are moving towards the poles and they just look like two umbrellas facing each other. In this diagram again in the circle you can see a telophase, a telophase in which the chromosomes have reached their destination to the poles and they start decondensing but yet cell is not divided. After this stereokinesis, nucleo division is complete. Now cell have to divide into cells. Now the cytokinesis or division of the cell is different in the animal and the plant cell. We talk about the plant cell first. In the plant cells as you can see in the diagram above in the center of the cell a plate or a line is formed. This plate is formed of some materials which are produced by the Golgi bodies of the cell. These materials start collecting inside the center when the nucleo division is complete and then this cell plate start moving towards or we can say start growing towards the sides of the cells. And ultimately it joins with the cell membrane and divides the cell into two. Now this cell plate have components of cell membrane in the cell wall so that it can make the cell membrane to separate the cells and then the cell wall as well. After that the cell divides into two different cells. Pytokinesis an animal cell is different. As you can see in a picture above when the nucleo division is complete in the animal cell a cleavage furrow is formed. We can say an invagination is formed in the center of the cell and this invagination continue to grow towards inside. As we know that in plants the cell plate was formed in the center and then it moves towards the external sides but in the animal cells a furrow or an invagination is formed in the center from the exterior and then it is moving towards or growing towards the interior of the cell and then it divides the cell into two. This process of cytokinesis in the animal cells is supported by the cytoskeletal elements the actin filaments and microtubules and other cytoskeletal elements help in this cleavage furrow formation they actually contract and stretch the cell membrane the plasma membrane towards inside and ultimately this invagination from all the sides join each other and divide the cell into two daughter cells. Now the division of cell is complete and the both cells are now called daughter cells these cells have equal number of chromosomes and almost equal quantity of the cytoplasm and organelles and all the other things.