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0:09 If you had to think about the most exciting day you ever had in a science classroom, which
0:14 day would that be?
0:16 Looking back through the years---we have a few.
0:18 The time we participated in an earthworm dissection.
0:21 The time we took apart an owl pellet.
0:24 The osmosis eggs.
0:25 All of the fruit flies in genetic experiments.
0:27 Oh, I could go on, but I will never forget one day in my 9th grade science class.
0:33 My teacher brought in pond water.
0:35 And I put one drop of pond water on a microscope slide and saw the most amazing thing ever…I
0:42 saw, an amoeba.
0:44 A single celled amoeba on that microscope slide, and
0:47 I was forever stuck on science from that point on.
0:51 Because I could not believe this little cell was there, alive on this slide, still eating
0:56 because that’s what amoebas do a lot.
0:58 To imagine that every person is actually made of billions of cells---of course not amoeba
1:04 cells but animals cells--- billions of animal cells, is fascinating.
1:10 In fact, it really makes you reflect on some of the incredible statements of the modern
1:15 cell theory.
1:16 The modern cell theory includes the following: 1st that the cell is the smallest living unit
1:21 in all organisms.
1:23 2nd that all living things are made of cells.
1:27 One or more cells.
1:29 The amoeba I observed was a single-celled organism, so unicellular.
1:35 Humans are made of many cells, so multicellular.
1:37 And 3rd, all cells come from other, pre-existing cells.
1:44 Cells have their own little world inside them.
1:47 They carry genetic information!
1:48 They can divide!
1:50 Many have functions and processes that their organelles, structures inside them, can take
1:54 care of.
1:56 On our planet, we can divide cells into two major groups.
1:59 As a cell, you’re either a prokaryote or an eukaryote.
2:04 Bacteria and Arachae are prokaryotes.
2:07 Everything else---plants, animals, fungi, protists----are eukaryotes.
2:13 Both prokaryotes and eukaryotes have genetic material.
2:17 Both have cytoplasm.
2:19 Both have ribosomes, which are small organelles that make proteins.
2:23 Both have cell membranes which control what goes in and out of the cell.
2:27 But what makes them different is a big deal.
2:31 Prokaryote---pro rhymes with no---they have no nucleus which holds the genetic material
2:37 and controls the cell’s activities.
2:40 Prokaryotes have no membrane bound organelles.
2:43 Membrane bound organelles are fancy organelles like the nucleus and mitochondria and golgi
2:48 apparatus.
2:50 Eukaryotes---eu rhymes with do----they do have membrane bound organelles.
2:55 So now you may be wondering what do the organelles do---what are their functions?
3:00 Well you know our style---we love our science with a side of comics.
3:05 So we want to take you on a tour of the ride of your life---into the inside of a cell!
3:12 To start our trip, we’re first going to have to get through this cell membrane, also
3:16 called a plasma membrane.
3:18 It’s selectively permeable which means that it only lets certain select materials in and
3:22 out.
3:23 By doing so, it keeps things in the cell stable---also known as keeping homeostasis.
3:28 We have an entire video on just the membrane
3:32 itself---which is found in all cells, but for now, we’re just going to have to squeeze
3:37 through this protein in the membrane.
3:40 Inside the cell, we find ourselves in this jelly like material called cytoplasm.
3:45 It surrounds all of these internal cell structures, and you’ll find it inside both prokaryotes
3:49 and eukaryotes.
3:51 Now organelles that are just floating around in the cytoplasm can have more support than
3:55 you might think.
3:56 Cells contain a cytoskeleton which is a collection of fibers that will provide support for the
4:01 cell and its organelles.
4:03 The cytoskeleton can even play a major role in movement.
4:06 The cytoskeleton actually deserves its own video though because it is very complex---and
4:11 its organization varies depending on what kind of cell you’re looking at.
4:16 Moving through this cytoplasm, let’s start with ribosomes.
4:19 They are NOT membrane bound organelles and they are going to be in both prokaryotes and
4:24 eukaryotes.
4:25 And they make protein.
4:26 Which is really important because that’s what so much of genetic material---DNA codes
4:33 for---protein.
4:34 Ribosomes can be free in the cytoplasm.
4:37 They can be attached to another organelle too, which we’ll talk about a bit later.
4:41 We are now going to focus on eukaryote organelles, which means, organelles that will be membrane
4:49 bound.
4:50 So this takes our travel to the big boss, the nucleus.
4:54 In eukaryotes, it holds the genetic material.
4:58 Genetic material as in DNA for example.
5:00 All cells have DNA but if you’re an eukaryote, you have a nucleus to put it in.
5:07 The nucleus controls the cell activities.
5:10 Inside it, it has a nucleolus, which is where ribosomes can be produced.
5:16 Attached to the membrane of the nucleus, or nuclear membrane, you can find the endoplasmic
5:21 reticulum.
5:22 ER for short.
5:24 It does a lot of processing of molecules for the cell---like protein folding----and it
5:29 also is highly involved in actually transporting those molecules around.
5:34 Like a highway!
5:35 There is rough ER which has ribosomes attached to it, making it---as you can imagine---rough.
5:42 And them smooth ER which doesn’t have the ribosomes.
5:44 Rough ER specifically tends to be involved with protein producing and transporting, because
5:50 remember that ribosomes make protein.
5:53 Molecules that leave the ER can be sent away in vesicles that actually pinch off of the
6:00 ER themselves.
6:01 Smooth ER has many additional roles including detoxification, which is one reason why your
6:06 liver cells tend to have a lot of smooth ER.
6:10 Another additional role of smooth ER is that it can make some types of lipids.
6:15 Next the Golgi apparatus.
6:17 It’s the ultimate packaging center.
6:19 It can receive items from the transport vesicles that pinched off of the ER.
6:24 It has enzymes that can modify molecules it may receive and it sorts the materials it
6:29 receives as well.
6:30 It can determine where to send those molecules---including some that may eventually be sent to the membrane
6:35 so they can be secreted, which means, items that can sent out of the cell.
6:40 So with all that’s going on in here, you might start to wonder…what’s powering
6:44 this thing?
6:45 The mighty mitochondria.
6:48 Or mitochondrion, if just talking about 1.
6:52 Like a power plant!
6:53 This thing makes ATP energy in a process called cellular respiration.
6:58 It’s not a type of power plant that you would think of…it runs on glucose, which
7:04 is a sugar, and needs the presence of oxygen to efficiently make ATP energy.
7:10 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.
7:19 We have a…fork in the road here.
7:22 For example, plant cells not only have mitochondria, but they also can have these awesome organelles
7:28 called chloroplasts.
7:30 Chloroplasts actually make glucose by using light energy in a process known as photosynthesis.
7:37 They tend to have a green look to them because they have a pigment that captures light energy
7:42 and reflects green light.
7:44 Both plant and animal cells can have vacuoles---now vacuoles can have a lot of different functions
7:49 but many types act as storage of materials.
7:53 Plant cells can have one large vacuole called a central vacuole while animal cells can have
7:59 several smaller vacuoles.
8:01 Remember how we already said that all cells have membranes?
8:06 Plant cells additionally have a cell wall which is a layer that offers additional protection
8:11 and shape maintenance that animal cells do not.
8:14 Hmm now how to get out of this animal cell we’ve been in?
8:19 Well…we could get out like a protein would.
8:21 So if we were a protein, we would only be made because of instructions from DNA and
8:27 remember that in Eukaryotes, DNA is found in the nucleus.
8:31 We would be made by a ribosome.
8:35 The ribosomes could be attached to the Rough ER.
8:38 The Rough ER highway would provide a vesicle to send us to the Golgi apparatus where the
8:43 sorting can take place.
8:44 And…if we’re tagged for being secreted...we’re sent off thru a vesicle from the Golgi to
8:51 the membrane.
8:52 And…out we go!
8:53 Just keep in mind that in our quick tour, there are still so many more awesome organelles
9:00 found in different types of eukaryote cells to continue exploring so to the Google for
9:05 more!
9:06 Well that’s it for the Amoeba Sisters and we remind you to stay curious!
