In this video, we're going to begin our introduction to cytokinesis. And so recall from our previous lesson videos that the m phase of the cell cycle consists of both mitosis and cytokinesis. Now already in our previous lesson videos we've covered the 5 phases of mitosis. And recall that mitosis ends up dividing the nucleus and at the end of mitosis, you still technically have a single cell with 2 nuclei. And so this means that mitosis needs to be followed up by another process called cytokinesis. And cytokinesis is technically the process that's going to produce 2 identical daughter cells separating the two nuclei. And so cytokinesis can be defined as the division of the cytoplasm, essentially separating the cells, separating 1 cell into 2 cells. And so it turns out that animal and plant cell cytokinesis actually differ in their mechanism. And so moving forward, we're going to talk about animal cytokinesis, and plant cytokinesis in their own separate videos. So I'll see you all in our next video to talk about animal cell cytokinesis.
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concept
Animal Cell Cytokinesis
Video duration:
2m
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Video transcript
In this video, we're going to introduce animal cell cytokinesis. And so in animal cells, cytokinesis is characterized by the formation of what's known as a cleavage furrow. And so a cleavage furrow is really just a small indentation of actin filaments mainly and some myosin filaments as well at the center of a dividing cell. And so this cleavage furrow ultimately is going to result in the pinching of the cytoplasm and the separation of the 2 cells. And so if we take a look at our image down below over here on the left hand side notice we're showing you a cell right after mitosis, and recall that mitosis technically ends with a single cell that has 2 nuclei. And so notice that we still have a single cell here, this is a cell that, is still a single cell because the cytoplasm is still connected here, And notice that there are 2 nuclei here. And so, what you'll notice is that mitosis technically does not end with 2 cells. And so mitosis needs to be followed up by the process of cytokinesis and cytokinesis is what's going to separate the cytoplasm, essentially separating this single cell to form 2 cells. And so during animal cell cytokinesis, a structure referred to as the cleavage furrow is going to form. And really the cleavage furrow is just this indentation, that you can see that forms and the indentation is forming from the result of these contractile actin microfilaments and myosin filaments that form in the middle, or in the center of the dividing cell. And so ultimately this cleavage furrow is going to continue to pinch off the cytoplasm until the cytoplasm has been divided and the 2 cells have their own cytoplasm and their own nucleus. And so these here would represent the daughter cells that result. And so technically, telophase which is the final phase of mitosis and cytokinesis are going to occur simultaneously which is why mitosis is technically is so highly linked to creating, 2 daughter cells. But technically it's the process of mitosis and cytokinesis that leads to the 2 daughter cells. And so this here concludes our introduction to animal cell cytokinesis and how it's characterized by the formation of the cleavage furrow And this is going to be different when we look at plant cell cytokinesis in our next video. So I'll see you all there.
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example
Cytokinesis Example 1
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1m
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Alright, so here we have an example problem that's asking why is cytokinesis an important part of cell division? And after reading through each of these four answer options down below, there are a few that we can eliminate right off the bat. And so taking a look at option d down below, it says that cytokinesis is responsible for the growth and production of new organelles and other cytoplasmic contents. But of course we know that this is not the role of cytokinesis, this option, option d, is more so the role of interphase. But interphase and cytokinesis are not the same thing. So we can go ahead and cross off answer option d. Answer option c says that cytokinesis is responsible for the linking of 2 sister chromatids, but of course that's not going to be the case, at all. That's not what we've discussed in our previous lesson videos. And And so now we're between answer option a and answer option b. And notice answer option a says that cytokinesis is responsible for the proper separation of genetic information. But technically it's mitosis that is separating the genetic information which is the DNA and separating the 2, the single nucleus to form 2 nuclei. And so really it's my ptosis that is responsible for the proper separation of the genetic information. And so mitosis is slightly different from cytokinesis, and so option A is more so linked to mitosis not cytokinesis. And so of course this only leaves answer option b here as the correct answer. And so cytokinesis is an important part of cell division because it is responsible for the proper separation of the cytoplasmic contents and that's really how cytokinesis is defined as division of the cytoplasm. And so answer option b here is gonna be correct answer for this example problem and that concludes this example so I'll see you all in our next video.
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Problem
Problem
In animal cell cytokinesis, a cleavage furrow is ________.
A
A ring of vesicles forming a cell wall.
B
The equatorial line which chromosomes align along during mitosis.
C
A groove in the plasma membrane between daughter nuclei.
D
The space that is created between two chromatids during anaphase.
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concept
Plant Cell Cytokinesis
Video duration:
3m
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Video transcript
In this video, we're going to introduce plant cell cytokinesis. And so plant cell cytokinesis is going to be different than animal cell cytokinesis because in plant cell cytokinesis, there is no cleavage furrow. And so what we need to recall from our previous lesson videos is that unlike animal cells, plant cells are actually surrounded by a cell wall. And so notice that in our image down below, the cell wall is color coordinated to this dark green color. And so what's important to note is that again in plant cell cytokinesis, there is no cleavage furrow that forms. Instead, vesicles from the Golgi apparatus are going to carry materials to generate what's known as a cell plate, and the cell plate is ultimately gonna be responsible for helping to separate each of the daughter cells. And so instead of a cleavage furrow forming, like what happens in animal cells, in plant cells a cell plate will form instead of the cleavage furrow. And so the cell plate you can really just think of as the precursor structure to a fully developed cell wall. And so the cell plate forms first and ultimately the cell plate ends up developing into a fully mature cell wall. And so if we take a look at our image down below, notice over here on the far left hand side, we are showing you a plant cell here that has a cell wall. And notice that this plant cell is undergoing mitosis, and so you can see here that it's undergoing anaphase where the sister chromatids are being pulled apart from one another. And notice that right here in the middle of the cell instead of a cleavage furrow forming, we have Golgi vesicles or vesicles from the Golgi apparatus starting to accumulate and form here in the middle of the cell. And again, recall that these vesicles from the Golgi apparatus are carrying the materials to generate a cell plate. So ultimately, what we're gonna see is that these Golgi vesicles are going to form a cell plate. And so notice that as mitosis continues here, there is a structure here forming in the middle of the cell referred to as the cell plate. And ultimately, this cell plate is going to continue to develop over time to form a fully mature cell wall, which is what we're labeling over here. And so once the fully mature cell wall has been formed, then the plant cell has successfully undergone a full complete cell division. And so again, the biggest takeaway here is that in animal cells, it's the cleavage furrow that forms, but in plant cells, it's the cell plate that forms and ends up developing into a cell wall. And so this here concludes our introduction to plant cell cytokinesis and we'll be able to get some practice applying these concepts as we move forward in our course. So I'll see you all in our next video.
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Problem
Problem
Which of the following are primarily responsible for cytokinesis in plant cells?
A
Kinetochores.
B
Golgi-derived vesicles.
C
Actin and myosin.
D
Metaphase plate.
E
Centrosomes.
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Problem
Problem
FtsZ is a bacterial cytoskeletal protein that forms a contractile ring involved in binary fission. Its function is analogous to ________.
A
the cleavage furrow of eukaryotic animal cells.
B
the cell plate of eukaryotic plant cells.
C
the mitotic spindle of eukaryotic cells.
D
the microtubule-organizing center of eukaryotic cells.