The video starts: You see red blood cells carried away very fast by a strong blood flow. Leukocytes (white blood cells) roll slowly on endothelial cells. (0:1 to 0:12) The surfaces of two cells are shown adhering at contact points between adhesion molecules (The adhesion molecules are a sugar called P-selectin). (0:13 to 0:25) (0:50- 1:20) We see the cell membrane (aka plasma membrane) composed of its lipid bilayer. The “bobbing balls” are the hydrophilic heads of the lipids in the bilayer. (1:21-1:27) You see a “chemokine”(a chemical messenger) in this case a protein-sugar molecular called proteoglycan. Depending on their composition the proteoglycans have different functions. The main function is for the cells to communicate with the outside environment of cells. 1:27- 1:35 Chemicals are binding to leukocytes which causes a series of cell signaling events to occur. The binding of these chemicals to the cell membranes stimulates leukocytes and triggers an intracellular cascade of signaling reactions. 1:43-1:47 In addition to lipids, the cell membrane has many kinds of proteins in its structure. There are some proteins embedded in the lipid bilayer. These are called membrane-bound proteins. The membrane-bound proteincomplexes are critical for the transmission of signals across the plasma membrane. 1:58 – 2:40 You get a good view of the cytoskeleton, which is comprised of networks of filamentous proteins (one of which is spectrin) that are responsible for the special organization of components of the cytoplasm of cells. 2:20 -3:17 Actin filaments, another protein component of the cytoskeleton- being assembled and disassembled (by a severing protein) 3:40 Microtubule Assembly and disassembly- Microtubules, another component of the cytoskeleton, is made up of the protein, tubulin. 3:41- 4:03 Wait, what? What is that thing dragging a “the big blue package” along that “little conveyor belt”? Kinesin is the “dragger”. Kinesin is a motor protein. Its job is to move proteins to where they are needed in a cell. The “package” is a vesicle, most likely filled with proteins that were packaged by the Golgi apparatus. 4:05- 4:15 Membrane-bound organelles like mitochondria are loosely trapped by the cytoskeleton. Mitochondria change shape continuously and their orientation is partly dictated by their interaction with microtubules. 4:16- 4:26 The centrosome is responsible for anchoring parts of the cytoskeleton for stability. You can see the two centrioles (the hollow cylinders) that are part of the centrosome. Each centrosome has two centrioles. Centrosomes are located near the nucleus, which we can see in the background. 4:27 -5:03 Now you are at the nucleus. Pores in the nuclear envelope (the membrane of the nucleus) allow the import of particles containing messenger RNA (mRNA) and proteins into the cytosol. Here, free ribosomes translate the mRNA molecules into proteins. Some of these proteins will reside in the cytosol while others will associate with specialized proteins and be imported into mitochondria or other organelles. What’s going on here? Messenger RNA (the string like structure, with a protein attached to it), having just left the nucleus with the DNA code, is being associated with a ribosome (made of 2 sub units) so that some protein-making can take place in the cytoplasm. (4:45) 5:05 – 5:32 Now we are at the surface of a mitochondrion. On its surface are translocators which are pores for proteins to enter the mitochondria. The proteins are most likely enzymes needed in the process of cellular respiration. 5:33: Here you are at the ER, with another motor protein trudging along in the foreground with its package (vesicle). A nascent protein (a protein that has not yet taken its final 3D shape) enters a pore in the ER, and you see another motor protein trudging along with a package in the foreground. 6:22: We are back at the plasma membrane. We see some proteins leaving the cell by exocytosis. 6:40 Here we see the chemical messengers (brown molecules) again (chemokines), binding to receptors (purple) on the cell membrane. 6:45- 7.04: The membrane embedded G-Protein, and other proteins are activated due to the inflammation in the area. This activation by all of these proteins causes the activation and clustering of integrins inside lipid rafts. 7.05: Neighboring endothelial cells with their I-CAM proteins “notice” all of this activation and signaling and subsequent events cause the leukocytes to stop rolling on the endothelial cells of the blood vessel.(7:27) 7:28-end: These strong interactions and additional signaling events, cause a profound reorganization of the cytoskeleton of the leukocyte, and gives it an “edge” This leading edge of the leukocyte inserts itself between the endothelial cells of the blood vessel, and we see the leukocyte leaving the blood vessel to go to the site of inflammation to go do its job!
Use what's below to answer the questions.
The video starts: You see red blood cells carried away very fast by a strong blood flow. Leukocytes (white blood cells) roll slowly on endothelial cells. (0:1 to 0:12)
The surfaces of two cells are shown adhering at contact points between adhesion molecules (The adhesion molecules are a sugar called P-selectin). (0:13 to 0:25)
(0:50- 1:20) We see the cell membrane (aka plasma membrane) composed of its lipid bilayer. The “bobbing balls” are the hydrophilic heads of the lipids in the bilayer.
(1:21-1:27) You see a “chemokine”(a chemical messenger) in this case a protein-sugar molecular called proteoglycan. Depending on their composition the proteoglycans have different functions. The main function is for the cells to communicate with the outside environment of cells.
1:27- 1:35 Chemicals are binding to leukocytes which causes a series of cell signaling events to occur. The binding of these chemicals to the cell membranes stimulates leukocytes and triggers an intracellular cascade of signaling reactions.
1:43-1:47
In addition to lipids, the cell membrane has many kinds of proteins in its structure. There are some proteins embedded in the lipid bilayer. These are called membrane-bound proteins. The membrane-bound proteincomplexes are critical for the transmission of signals across the plasma membrane.
1:58 – 2:40
You get a good view of the cytoskeleton, which is comprised of networks of filamentous proteins (one of which is spectrin) that are responsible for the special organization of components of the cytoplasm of cells.
2:20 -3:17 Actin filaments, another protein component of the cytoskeleton- being assembled and disassembled (by a severing protein)
3:40 Microtubule Assembly and disassembly- Microtubules, another component of the cytoskeleton, is made up of the protein, tubulin.
3:41- 4:03 Wait, what? What is that thing dragging a “the big blue package” along that “little conveyor belt”? Kinesin is the “dragger”. Kinesin is a motor protein. Its job is to move proteins to where they are needed in a cell. The “package” is a vesicle, most likely filled with proteins that were packaged by the Golgi apparatus.
4:05- 4:15 Membrane-bound organelles like mitochondria are loosely trapped by the cytoskeleton. Mitochondria change shape continuously and their orientation is partly dictated by their interaction with microtubules.
4:16- 4:26 The centrosome is responsible for anchoring parts of the cytoskeleton for stability. You can see the two centrioles (the hollow cylinders) that are part of the centrosome. Each centrosome has two centrioles. Centrosomes are located near the nucleus, which we can see in the background.
4:27 -5:03 Now you are at the nucleus. Pores in the nuclear envelope (the membrane of the nucleus) allow the import of particles containing messenger RNA (mRNA) and proteins into the cytosol. Here, free ribosomes translate the mRNA molecules into proteins. Some of these proteins will reside in the cytosol while others will associate with specialized proteins and be imported into mitochondria or other organelles.
What’s going on here? Messenger RNA (the string like structure, with a protein attached to it), having just left the nucleus with the DNA code, is being associated with a ribosome (made of 2 sub units) so that some protein-making can take place in the cytoplasm. (4:45)
5:05 – 5:32 Now we are at the surface of a mitochondrion. On its surface are translocators which are pores for proteins to enter the mitochondria. The proteins are most likely enzymes needed in the process of
5:33: Here you are at the ER, with another motor protein trudging along in the foreground with its package (vesicle). A nascent protein (a protein that has not yet taken its final 3D shape) enters a pore in the ER, and you see another motor protein trudging along with a package in the foreground.
6:22: We are back at the plasma membrane. We see some proteins leaving the cell by exocytosis.
6:40 Here we see the chemical messengers (brown molecules) again (chemokines), binding to receptors (purple) on the cell membrane.
6:45- 7.04: The membrane embedded G-Protein, and other proteins are activated due to the inflammation in the area. This activation by all of these proteins causes the activation and clustering of integrins inside lipid rafts.
7.05: Neighboring endothelial cells with their I-CAM proteins “notice” all of this activation and signaling and subsequent events cause the leukocytes to stop rolling on the endothelial cells of the blood vessel.(7:27)
7:28-end: These strong interactions and additional signaling events, cause a profound reorganization of the cytoskeleton of the leukocyte, and gives it an “edge” This leading edge of the leukocyte inserts itself between the endothelial cells of the blood vessel, and we see the leukocyte leaving the blood vessel to go to the site of inflammation to go do its job!
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