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Current time:0:00Total duration:4:25

Introduction to cilia, flagella and pseudopodia

AP.BIO:
ENE‑1 (EU)
,
ENE‑1.B.1 (EK)

Video transcript

the goal of this video is to appreciate some of the structures that you see even in unicellular organisms so this right over here is a picture of the amoeba chaos caralyn NC and what you see here is a projection coming off from the main part of the cell and this is called a pseudo pod which is referring to it being a false foot the pod is coming from the same root word as podiatry which is referring to the foot and what I really want you to appreciate this is used by amoeba either to move around or could be even used to attack something that it wants to engulf and think about what it might take to be able to do this to be able to grow this type of a pseudo foot this type of a false foot you need all sorts of micro structures in here that will extend or contract as necessary and think about the machinery that you need to do that and so the key realization is sometimes we just imagine cells as these bags of fluid with a few things floating around but there are these incredibly complex structures and biologists even today don't fully understand how everything works and they're studying how these things actually come to be now another structure that you will often see on unicellular organisms that either help them move around or even help move other things around are cilia so this right over here is a picture of oxy Trika trifle ax which is a unicellular organism it's a eukaryote and you can clearly see these projections from its body here these hairlike structures remember this is a unicellular organism if we were to it's actually a fairly it's a decent-sized one that would be about something like that would be about 30 micrometers right over there or 30 million of a meter or 30 thousandths of a millimeter so small by our scale but it's actually pretty big on the scale of it being a cell and once again these cilia tend to move in unison to either allow the microorganism to move around or sometimes they're used to move other things around for example the cells that line your lungs will have cilia that are used to move things up or down to move some of the saliva or any particles that are in there now oxy trike a trifle axe is particularly interesting is a carry-out because it doesn't just have one nucleus it can have two nuclei and within the nucleus its DNA can be extremely fragmented most organisms have a reasonable number of chromosomes human beings have 23 pair and that's actually a fairly large number oxi troika trifle ax could have thousands of chromosomes and what's really interesting about ox attract a trifle ax is how it mates when it is under stress it will merge with another oxy trike a trifle ax and instead of producing another offspring they mingle their DNA together so by mating they change each other's genetic makeup which is fascinating and depending on your perspective highly romantic now another related idea is instead of having many cilia some unicellular organisms will just have one large thing that looks like a tail that they can whip around to move so this right over here is a commonly studied green algae it's called clamored de moniz and you can see very clearly here this flagellum this tail like structure and this is extremely thin we're seeing it under a very powerful microscope right over here but just to get a sense of scale a micrometer here would be about that so the width of this flagellum flagellum would be the singular if we were talking about many of these we would say flagella this is about 1/4 of a micrometer another way of thinking about it you could put 4,000 of these side-by-side and you would have the width of a millimeter so extremely extremely small but once again it really is amazing that these what seem like simple organisms to us are actually quite complex there's a whole study of how these flagella move around how the the cell can spin it around so it allows it to move if you were to actually decompose what's going on in this part of the cell it's actually quite complex it's biological machinery going on so once again these cells are not these just bags of just a few things floating around they're incredibly complex structures that we are still trying to understand
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