WEBVTT 00:00:00.000 --> 00:00:03.800 (MUSIC) 00:00:03.800 --> 00:00:09.160 (MUSIC) 00:00:09.540 --> 00:00:14.660 If you had to think about the most exciting day you ever had in a science classroom, which 00:00:14.660 --> 00:00:16.619 day would that be? 00:00:16.619 --> 00:00:18.820 Now, looking back through the years---we have a few. 00:00:18.820 --> 00:00:21.960 The time we participated in an earthworm dissection. 00:00:21.960 --> 00:00:24.330 The time we took apart an owl pellet. 00:00:24.330 --> 00:00:25.890 The osmosis eggs. 00:00:25.890 --> 00:00:27.900 All of the fruit flies in genetic experiments. 00:00:27.900 --> 00:00:33.050 Oh, I could go on, but I will never forget one day in my 9th grade science class. 00:00:33.050 --> 00:00:35.269 My teacher brought in pond water. 00:00:35.269 --> 00:00:42.129 And I put one drop of pond water on a microscope slide and saw the most amazing thing ever…I 00:00:42.129 --> 00:00:44.850 saw, an amoeba. 00:00:44.850 --> 00:00:47.420 A single celled amoeba on that microscope slide, and 00:00:47.420 --> 00:00:51.030 I was forever stuck on science from that point on. 00:00:51.030 --> 00:00:56.460 Because I could not believe this little cell was there, alive on this slide, still eating 00:00:56.460 --> 00:00:58.559 because that’s what amoebas do a lot. 00:00:58.559 --> 00:01:04.819 To imagine that every person is actually made of billions of cells---of course not amoeba 00:01:04.819 --> 00:01:10.250 cells but animals cells--- billions of animal cells, that's fascinating. 00:01:10.250 --> 00:01:15.229 In fact, it really makes you reflect on some of the incredible statements of the modern 00:01:15.229 --> 00:01:16.700 cell theory. 00:01:16.700 --> 00:01:21.770 The modern cell theory includes the following: First that the cell is the smallest living unit 00:01:21.770 --> 00:01:23.570 in all organisms. 00:01:23.570 --> 00:01:27.369 Second that all living things are made of cells. 00:01:27.369 --> 00:01:29.469 One or more cells. 00:01:29.469 --> 00:01:35.240 The amoeba I observed was a single-celled organism, so unicellular. 00:01:35.240 --> 00:01:37.960 Humans are made of many cells, so multicellular. 00:01:37.960 --> 00:01:44.319 And third, all cells come from other pre-existing cells. 00:01:44.319 --> 00:01:47.149 Cells have their own little world inside them. 00:01:47.149 --> 00:01:48.579 They carry genetic information! 00:01:48.579 --> 00:01:50.460 They can divide! 00:01:50.460 --> 00:01:54.979 Many have functions and processes that their organelles, structures inside them, can take 00:01:54.979 --> 00:01:56.249 care of. 00:01:56.249 --> 00:01:59.770 On our planet, we can divide cells into two major groups. 00:01:59.770 --> 00:02:04.600 As a cell, you’re either a prokaryote or an eukaryote. 00:02:04.600 --> 00:02:07.400 Bacteria and arachae are prokaryotes. 00:02:07.400 --> 00:02:13.230 But everything else---plants, animals, fungi, protists----are eukaryotes. 00:02:13.230 --> 00:02:17.270 Both prokaryotes and eukaryotes have genetic material. 00:02:17.270 --> 00:02:19.340 Both have cytoplasm. 00:02:19.340 --> 00:02:23.680 Both have ribosomes, which are small organelles that make proteins. 00:02:23.680 --> 00:02:27.720 Both have cell membranes which control what goes in and out of the cell. 00:02:27.720 --> 00:02:31.670 But what makes them different is a big deal. 00:02:31.670 --> 00:02:37.550 Prokaryote---the "pro" rhymes with "no"---they have no nucleus which holds the genetic material 00:02:37.550 --> 00:02:40.220 and controls the cell’s activities. 00:02:40.220 --> 00:02:43.770 Prokaryotes have no membrane-bound organelles. 00:02:43.770 --> 00:02:48.890 Membrane-bound organelles are fancy organelles like the nucleus and mitochondria and Golgi 00:02:48.890 --> 00:02:50.580 apparatus. 00:02:50.580 --> 00:02:55.950 Eukaryotes---the "eu" rhymes with "Do"----they do have membrane bound organelles. 00:02:55.950 --> 00:03:00.790 So, now you may be wondering what do the organelles do---what are their functions? 00:03:00.790 --> 00:03:05.760 Well you know our style---we love our science with a side of comics. 00:03:05.760 --> 00:03:12.430 So, we want to take you on a tour of the ride of your life---into the inside of a cell! 00:03:12.430 --> 00:03:16.670 To start our trip, we’re first going to have to get through this cell membrane, also 00:03:16.670 --> 00:03:18.420 called a plasma membrane. 00:03:18.420 --> 00:03:22.950 It’s selectively permeable which means that it only lets certain select materials in and 00:03:22.950 --> 00:03:23.950 out. 00:03:23.950 --> 00:03:28.880 By doing so, it keeps things in the cell stable---also known as keeping homeostasis. 00:03:28.880 --> 00:03:32.190 We have an entire video on just the membrane 00:03:32.190 --> 00:03:37.290 itself---which is found in all cells, but for now, we’re just going to have to squeeze 00:03:37.290 --> 00:03:40.360 through this protein in the membrane. 00:03:40.360 --> 00:03:45.050 Now, inside the cell, we find ourselves in this jelly-like material called cytoplasm. 00:03:45.050 --> 00:03:49.830 It surrounds all of these internal cell structures, and you’ll find it inside both prokaryotes 00:03:49.830 --> 00:03:51.760 and eukaryotes. 00:03:51.760 --> 00:03:55.400 Now organelles that are floating around in the cytoplasm can have more support than 00:03:55.400 --> 00:03:56.800 you might think. 00:03:56.800 --> 00:04:01.710 Cells contain a cytoskeleton which is a collection of fibers that can provide support for the 00:04:01.710 --> 00:04:03.080 cell and its organelles. 00:04:03.080 --> 00:04:06.540 The cytoskeleton can even play a major role in cell movement. 00:04:06.540 --> 00:04:11.610 The cytoskeleton actually deserves its own video because it is very complex---and 00:04:11.610 --> 00:04:16.220 its organization can vary depending on what kind of cell you’re looking at. 00:04:16.220 --> 00:04:19.459 Moving through this cytoplasm, let’s start with ribosomes. 00:04:19.459 --> 00:04:24.660 They are NOT membrane-bound organelles and they are going to be in both prokaryotes and 00:04:24.660 --> 00:04:25.660 eukaryotes. 00:04:25.660 --> 00:04:26.930 They make protein, 00:04:26.930 --> 00:04:33.159 which is really important because that’s what so much of genetic material---DNA codes 00:04:33.159 --> 00:04:34.319 for---protein. 00:04:34.319 --> 00:04:37.300 Ribosomes can be free in the cytoplasm, 00:04:37.300 --> 00:04:41.409 but they can be attached to another organelle too, which we’ll talk about a bit later. 00:04:41.409 --> 00:04:48.340 We are now going to focus on organelles, the membrane bound. So, we are going to be focussing on organelles that you would find in an 00:04:48.340 --> 00:04:50.340 eukaryote cell. 00:04:50.340 --> 00:04:54.930 This takes our travel to the big boss, the nucleus. 00:04:54.930 --> 00:04:58.200 Now in eukaryotes, it holds the genetic material. 00:04:58.200 --> 00:05:00.550 Genetic material as in DNA for example. 00:05:00.550 --> 00:05:07.770 Both prokaryotes and eukaryotes have DNA but if you’re an eukaryote, you have a nucleus to put it in. 00:05:07.770 --> 00:05:10.759 The nucleus controls the cell's activities and 00:05:10.759 --> 00:05:16.439 inside it, it has a nucleolus, which is where ribosomes can be produced. 00:05:16.439 --> 00:05:21.939 Attached to the membrane of the nucleus or nuclear membrane, you can find the endoplasmic 00:05:21.939 --> 00:05:22.939 reticulum. 00:05:22.939 --> 00:05:24.960 ER for short. 00:05:24.960 --> 00:05:29.889 It does a lot of processing of molecules for the cell---like protein folding----and it 00:05:29.889 --> 00:05:34.340 also is highly involved in actually transporting those molecules around. 00:05:34.340 --> 00:05:35.340 Like a highway! 00:05:35.340 --> 00:05:42.009 There is rough ER which has ribosomes attached to it, making it---as you can imagine---rough. 00:05:42.009 --> 00:05:44.719 And them smooth ER which doesn’t have the ribosomes. 00:05:44.719 --> 00:05:50.871 Rough ER specifically tends to be involved with protein producing and transporting, because 00:05:50.871 --> 00:05:53.919 remember that ribosomes make protein. 00:05:53.919 --> 00:06:00.169 Molecules that leave the ER can be sent away in vesicles that actually pinch off of the 00:06:00.169 --> 00:06:01.169 ER themselves. 00:06:01.169 --> 00:06:06.719 Now, smooth ER has many additional roles including detoxification, which is one reason why your 00:06:06.719 --> 00:06:10.240 liver cells tend to have a lot of smooth ER. 00:06:10.240 --> 00:06:15.050 Another additional role of smooth ER is that it can make some types of lipids. 00:06:15.050 --> 00:06:17.050 Next, the Golgi apparatus. 00:06:17.050 --> 00:06:19.909 It’s the ultimate packaging center. 00:06:19.909 --> 00:06:24.509 It can receive items from the transport vesicles that pinched off the ER. 00:06:24.509 --> 00:06:29.430 It has enzymes that can modify molecules it may receive and it sorts the materials it 00:06:29.430 --> 00:06:30.760 receives as well. 00:06:30.760 --> 00:06:35.789 It can determine where to send those molecules---including some that may eventually be sent to the membrane 00:06:35.789 --> 00:06:40.630 so they can be secreted, which means, items that can sent out of the cell. 00:06:40.630 --> 00:06:44.449 So, with all that’s going on in here, you might start to wonder…what’s powering 00:06:44.449 --> 00:06:45.690 this thing? 00:06:45.690 --> 00:06:48.020 The mighty mitochondria 00:06:48.020 --> 00:06:52.099 or mitochondrion, if just talking about one. 00:06:52.099 --> 00:06:53.270 They are like power plants! 00:06:53.270 --> 00:06:58.400 The mitochondria make ATP energy in a process called cellular respiration. 00:06:58.400 --> 00:07:04.169 It’s not a type of power plant that you might think of…it runs on glucose, which 00:07:04.169 --> 00:07:10.669 is a sugar, and needs the presence of oxygen to efficiently make ATP energy. 00:07:10.669 --> 00:07:19.599 Now at this point, we need to mention that eukaryotes are not a one-size-fits-all. Animal cells can have differences from plant cells. 00:07:19.599 --> 00:07:22.800 We have a…fork in the road here. 00:07:22.800 --> 00:07:28.550 For example, plant cells not only have mitochondria, but they also can have these awesome organelles 00:07:28.550 --> 00:07:30.620 called chloroplasts. 00:07:30.620 --> 00:07:37.210 Chloroplasts actually make glucose by using light energy in a process known as photosynthesis. 00:07:37.210 --> 00:07:42.520 They tend to have a green look to them because they have a pigment that captures light energy 00:07:42.520 --> 00:07:44.990 and reflects green light. 00:07:44.990 --> 00:07:49.599 Now, both plant and animal cells can have vacuoles---now vacuoles can have a lot of different functions 00:07:49.599 --> 00:07:53.509 but many types act as storage of materials. 00:07:53.509 --> 00:07:59.460 Plant cells can have one large vacuole called a central vacuole while animal cells can have 00:07:59.460 --> 00:08:01.410 several smaller vacuoles. 00:08:01.410 --> 00:08:06.050 Remember how we already said that all cells have membranes? They do. 00:08:06.050 --> 00:08:11.189 But plant cells additionally have a cell wall which is a layer that offers additional protection 00:08:11.189 --> 00:08:14.310 and shape maintenance that animal cells do not. 00:08:14.310 --> 00:08:19.409 Hmm now how do we get out of this animal cell that we’ve been in? 00:08:19.409 --> 00:08:21.740 Well, we could get out like a protein would. 00:08:21.740 --> 00:08:27.460 So, if we were a protein, we would only be made because of instructions from DNA and 00:08:27.460 --> 00:08:31.639 remember that in eukaryotes, DNA is found in the nucleus. 00:08:31.639 --> 00:08:35.659 We would be made by a ribosome. 00:08:35.659 --> 00:08:38.219 The ribosomes could be attached to the rough ER. 00:08:38.219 --> 00:08:43.679 And the rough ER highway would provide a vesicle to send us to the Golgi apparatus where 00:08:43.679 --> 00:08:44.839 sorting can take place. 00:08:44.839 --> 00:08:51.810 And…if we’re tagged for being secreted...we’re sent off through a vesicle from the Golgi to 00:08:51.810 --> 00:08:52.810 the membrane. 00:08:52.810 --> 00:08:53.830 And…out we go! 00:08:53.830 --> 00:09:00.029 Just keep in mind that in our quick tour, there are still so many more awesome organelles 00:09:00.029 --> 00:09:05.860 found in lots of different types of eukaryote cells to continue exploring, so to the Google for 00:09:05.860 --> 00:09:06.860 more! 00:09:06.860 --> 00:09:11.300 Well that’s it for the Amoeba Sisters and we remind you to stay curious!