Introduction to Cells: The Grand Cell Tour — Transcript

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1. 0:09If you had to think about the most exciting day you ever had in a science classroom, which
2. 0:14day would that be?
3. 0:16Looking back through the years---we have a few.
4. 0:18The time we participated in an earthworm dissection.
5. 0:21The time we took apart an owl pellet.
6. 0:24The osmosis eggs.
7. 0:25All of the fruit flies in genetic experiments.
8. 0:27Oh, I could go on, but I will never forget one day in my 9th grade science class.
9. 0:33My teacher brought in pond water.
10. 0:35And I put one drop of pond water on a microscope slide and saw the most amazing thing ever…I
11. 0:42saw, an amoeba.
12. 0:44A single celled amoeba on that microscope slide, and
13. 0:47I was forever stuck on science from that point on.
14. 0:51Because I could not believe this little cell was there, alive on this slide, still eating
15. 0:56because that’s what amoebas do a lot.
16. 0:58To imagine that every person is actually made of billions of cells---of course not amoeba
17. 1:04cells but animals cells--- billions of animal cells, is fascinating.
18. 1:10In fact, it really makes you reflect on some of the incredible statements of the modern
19. 1:15cell theory.
20. 1:16The modern cell theory includes the following: 1st that the cell is the smallest living unit
21. 1:21in all organisms.
22. 1:232nd that all living things are made of cells.
23. 1:27One or more cells.
24. 1:29The amoeba I observed was a single-celled organism, so unicellular.
25. 1:35Humans are made of many cells, so multicellular.
26. 1:37And 3rd, all cells come from other, pre-existing cells.
27. 1:44Cells have their own little world inside them.
28. 1:47They carry genetic information!
29. 1:48They can divide!
30. 1:50Many have functions and processes that their organelles, structures inside them, can take
31. 1:54care of.
32. 1:56On our planet, we can divide cells into two major groups.
33. 1:59As a cell, you’re either a prokaryote or an eukaryote.
34. 2:04Bacteria and Arachae are prokaryotes.
35. 2:07Everything else---plants, animals, fungi, protists----are eukaryotes.
36. 2:13Both prokaryotes and eukaryotes have genetic material.
37. 2:17Both have cytoplasm.
38. 2:19Both have ribosomes, which are small organelles that make proteins.
39. 2:23Both have cell membranes which control what goes in and out of the cell.
40. 2:27But what makes them different is a big deal.
41. 2:31Prokaryote---pro rhymes with no---they have no nucleus which holds the genetic material
42. 2:37and controls the cell’s activities.
43. 2:40Prokaryotes have no membrane bound organelles.
44. 2:43Membrane bound organelles are fancy organelles like the nucleus and mitochondria and golgi
45. 2:48apparatus.
46. 2:50Eukaryotes---eu rhymes with do----they do have membrane bound organelles.
47. 2:55So now you may be wondering what do the organelles do---what are their functions?
48. 3:00Well you know our style---we love our science with a side of comics.
49. 3:05So we want to take you on a tour of the ride of your life---into the inside of a cell!
50. 3:12To start our trip, we’re first going to have to get through this cell membrane, also
51. 3:16called a plasma membrane.
52. 3:18It’s selectively permeable which means that it only lets certain select materials in and
53. 3:22out.
54. 3:23By doing so, it keeps things in the cell stable---also known as keeping homeostasis.
55. 3:28We have an entire video on just the membrane
56. 3:32itself---which is found in all cells, but for now, we’re just going to have to squeeze
57. 3:37through this protein in the membrane.
58. 3:40Inside the cell, we find ourselves in this jelly like material called cytoplasm.
59. 3:45It surrounds all of these internal cell structures, and you’ll find it inside both prokaryotes
60. 3:49and eukaryotes.
61. 3:51Now organelles that are just floating around in the cytoplasm can have more support than
62. 3:55you might think.
63. 3:56Cells contain a cytoskeleton which is a collection of fibers that will provide support for the
64. 4:01cell and its organelles.
65. 4:03The cytoskeleton can even play a major role in movement.
66. 4:06The cytoskeleton actually deserves its own video though because it is very complex---and
67. 4:11its organization varies depending on what kind of cell you’re looking at.
68. 4:16Moving through this cytoplasm, let’s start with ribosomes.
69. 4:19They are NOT membrane bound organelles and they are going to be in both prokaryotes and
70. 4:24eukaryotes.
71. 4:25And they make protein.
72. 4:26Which is really important because that’s what so much of genetic material---DNA codes
73. 4:33for---protein.
74. 4:34Ribosomes can be free in the cytoplasm.
75. 4:37They can be attached to another organelle too, which we’ll talk about a bit later.
76. 4:41We are now going to focus on eukaryote organelles, which means, organelles that will be membrane
77. 4:49bound.
78. 4:50So this takes our travel to the big boss, the nucleus.
79. 4:54In eukaryotes, it holds the genetic material.
80. 4:58Genetic material as in DNA for example.
81. 5:00All cells have DNA but if you’re an eukaryote, you have a nucleus to put it in.
82. 5:07The nucleus controls the cell activities.
83. 5:10Inside it, it has a nucleolus, which is where ribosomes can be produced.
84. 5:16Attached to the membrane of the nucleus, or nuclear membrane, you can find the endoplasmic
85. 5:21reticulum.
86. 5:22ER for short.
87. 5:24It does a lot of processing of molecules for the cell---like protein folding----and it
88. 5:29also is highly involved in actually transporting those molecules around.
89. 5:34Like a highway!
90. 5:35There is rough ER which has ribosomes attached to it, making it---as you can imagine---rough.
91. 5:42And them smooth ER which doesn’t have the ribosomes.
92. 5:44Rough ER specifically tends to be involved with protein producing and transporting, because
93. 5:50remember that ribosomes make protein.
94. 5:53Molecules that leave the ER can be sent away in vesicles that actually pinch off of the
95. 6:00ER themselves.
96. 6:01Smooth ER has many additional roles including detoxification, which is one reason why your
97. 6:06liver cells tend to have a lot of smooth ER.
98. 6:10Another additional role of smooth ER is that it can make some types of lipids.
99. 6:15Next the Golgi apparatus.
100. 6:17It’s the ultimate packaging center.
101. 6:19It can receive items from the transport vesicles that pinched off of the ER.
102. 6:24It has enzymes that can modify molecules it may receive and it sorts the materials it
103. 6:29receives as well.
104. 6:30It can determine where to send those molecules---including some that may eventually be sent to the membrane
105. 6:35so they can be secreted, which means, items that can sent out of the cell.
106. 6:40So with all that’s going on in here, you might start to wonder…what’s powering
107. 6:44this thing?
108. 6:45The mighty mitochondria.
109. 6:48Or mitochondrion, if just talking about 1.
110. 6:52Like a power plant!
111. 6:53This thing makes ATP energy in a process called cellular respiration.
112. 6:58It’s not a type of power plant that you would think of…it runs on glucose, which
113. 7:04is a sugar, and needs the presence of oxygen to efficiently make ATP energy.
114. 7:10Now at this point, we need to mention that eukaryotes are not a one size fits all. Animal cells can have differences from plant cells.
115. 7:19We have a…fork in the road here.
116. 7:22For example, plant cells not only have mitochondria, but they also can have these awesome organelles
117. 7:28called chloroplasts.
118. 7:30Chloroplasts actually make glucose by using light energy in a process known as photosynthesis.
119. 7:37They tend to have a green look to them because they have a pigment that captures light energy
120. 7:42and reflects green light.
121. 7:44Both plant and animal cells can have vacuoles---now vacuoles can have a lot of different functions
122. 7:49but many types act as storage of materials.
123. 7:53Plant cells can have one large vacuole called a central vacuole while animal cells can have
124. 7:59several smaller vacuoles.
125. 8:01Remember how we already said that all cells have membranes?
126. 8:06Plant cells additionally have a cell wall which is a layer that offers additional protection
127. 8:11and shape maintenance that animal cells do not.
128. 8:14Hmm now how to get out of this animal cell we’ve been in?
129. 8:19Well…we could get out like a protein would.
130. 8:21So if we were a protein, we would only be made because of instructions from DNA and
131. 8:27remember that in Eukaryotes, DNA is found in the nucleus.
132. 8:31We would be made by a ribosome.
133. 8:35The ribosomes could be attached to the Rough ER.
134. 8:38The Rough ER highway would provide a vesicle to send us to the Golgi apparatus where the
135. 8:43sorting can take place.
136. 8:44And…if we’re tagged for being secreted...we’re sent off thru a vesicle from the Golgi to
137. 8:51the membrane.
138. 8:52And…out we go!
139. 8:53Just keep in mind that in our quick tour, there are still so many more awesome organelles
140. 9:00found in different types of eukaryote cells to continue exploring so to the Google for
141. 9:05more!
142. 9:06Well that’s it for the Amoeba Sisters and we remind you to stay curious!