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138 Cards in this Set
- Front
- Back
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the protein sub units that make up microtubles are ______________ and ___________. |
a and b tubulin |
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the protein sub units that make up intermediate filaments are ____________, ___________, and ____________. |
keratin, vimentin, desmin |
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the protein sub unit that makes up the micro filament is ____________. |
g- actin |
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do microtubules have polarity? |
yes |
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do intermediate filaments have polarity? |
no |
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do microfiliaments have polarity? |
yes |
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the motor proteins found in microtubules are _____, and _______. |
kinesin, dynein |
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are there motor proteins found in intermediate filaments? |
no, there aren't any |
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microtubles are distributed in prokaryotes, eukaryotes, or animal cells? |
eukaryotes |
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intermediate filaments are distributed in prokaryotes, eukaryotes, or animal cells? |
animal cells |
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microfilaments are distributed in eurkaryotes, animals cells, or prokaryotes? |
eukaryotes |
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what do microtubles function to do? |
provide support and motility |
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what do intermediate filaments function to do? |
provide support |
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what do microfilaments function to do? |
provide motility and contractility |
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the structure of __________ contains a hollow tube with a wall consisting of 13 photofilaments. |
microtubules |
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____________ are structures that are two intertwined chains of F actin. |
microfilaments |
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______________ are structures that contains eight protofilaments joined together from end to end with staggered overlaps. |
intermediate filaments |
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___________ are built with tubulin proteins as dimers. right down the middle of the protein is a seam of alpha and beta tubulin proteins |
microtubles |
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can tubulin be added on both postive and negative ends of mictrobule? |
yes |
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as time progresses with the addition of tubulin sub units on microtubules what is the step wise process? |
individual dimers---------> oligomers-----------> protofilaments------> growing microtubule |
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what two motor proteins 'walk' along microtubules carrying organelles as carge, and require ATP hydrolysis. |
Dynein and kinesin |
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what is the motor movement of dynein and kinesin on a microtubule? |
the motor proteins walk in opposite directions. |
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microtubules and their motor proteins move ______________ inside the cell, and stabilize the ___________. |
organelles, and Golgi complex |
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what do MTOC's (microtubule organizing centers) do? |
act as anchors for spindle fibers called kinetochores, and act as anchors for microtubules for cilia and flagella. |
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______ and __________ are structures that require micrtubules, MTOC's, and motor proteins. |
cilia, Flagella |
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__________ are not polarized, do not have motor proteins, and are very stable. it is very cell type specific like epithelial cells, fibroblasts, and muscle cells. |
intermediate filaments |
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_____________ are the smallest cytoskeletal unit. _________ assembles to form f actin, the polarized version of this cytoskeletal unit. |
microfilaments g actin |
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____________ are the fan shaped structure formed by migrating non muscle cells. ____________ is assembled inside the cell within this structure. |
lamellipodia actin |
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________ are finger like projections that cells use to "feel out" their environment. actin cytoskeleton is also assembled within this structure. |
filopodia |
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____________ are the lines of actin inside a cell that generate tension for contraction. |
stress fibers |
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cytoskeletal interaction with the environment requires__________ and ___________. |
focal adhesions integrins |
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many cells spend all their lives in contact with _________ cells. |
neighboring |
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the organization of cells into tissues allows multiceullular organisms to adopt what? |
complex strucutres |
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there are two types of tissues found in animals. what are they? |
Epithelium connective tissue |
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______ tissues contain sheets of cells that are polarized, and have discrete functional domains at opposite ends of the cells. |
epithelium |
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__________ tissues are more loosely organized, in which cells are attached to each other, a rigid scaffold, or both. |
connective |
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what are the three types of extra cellular matrix tissue (ECM)? |
Bone cartilage connective tissue |
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______ consists mainly of a rigid extracellular matrix that contains a small number of interspersed cells. |
bone |
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__________ is a tissue constructed mostly of matrix materials that is more flexible than bones |
cartilage |
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_________ tissue surrounding glands as well as blood vessels, is relatively gelatinous and contains interspersed fibroblast cells. |
connective |
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ECM consists of the same three classes of molecules. what are they? |
Structural proteins like collagen or elastins that provide strength and flexibility protein polysaccharide complexes like proteoglycans adhesive glycoproteins like fibronectins or lamins that allow cells to attach to matrix. |
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what is the extracellular structure of a plant? what about an animal? |
plant: the cell wall animal: extracellular matrix |
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what is the structural fiber of an animal cells? what about a plant cell? |
animal: collagens and elastins plant: cellulose |
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what are the components of hydrated matrix of an animal cell? what about a plant cell? |
animal cell: proteoglycans plant cell: hemicelluloses, extensins |
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what adhesive molecules are found in animals cells? what about plants? |
animal cells: fibronectins, laminins plant cells: pectins |
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_________ are responsible for the strength of the extracellular matrix. they are also the most abundant component in the ECM that form fibers witht high tensile strenth |
collagens |
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____________ is secreted by several types of cells in connective tissues including fibroblasts. |
collagen |
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all collagens occur as a rigid _______ of interwined polypeptides.
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triple helix
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__________ have an unusual amino acid composition that is very high in glycine and the rare amino acids hydroxlysine and hydroxyproline.
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collagens
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the _________ spacing in collagens are important informing a helix
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glycine
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collagen fibers are visible in the ECM under what?
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scanning EM (electron microscope)
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collagen fibers are enormously strong and are composed of numerous ________. these components are made up of three a-chains twisted into a helix.
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fibrils
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___________ is a precursor that forms many types of tissue specific collagens.
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procollagen
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in what part of the cell do three a-chains assemble to form a triple helix called procollagen?
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in the lumen of the ER
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one procollagen is secreted out of the cell, what happens next?
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it gets spit by procollagen peptidase, to remove both ends of the molecule.
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what happens to the resulting collagen molecules that get split off from from procollagen fibers by procallagen peptidase enyzmes?
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the collagen molecules spontaneously associate into fibrils and then into fibers.
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what type of bond (involes hydroxylsine and hydroxyproline) reinforces the stability of collagen fibrils?
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hydrogen bonds
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what do the hydrogen bonds form within and between collagen molecules?
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crosslinks
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_______ impart elasticity and flexibility to the extraceullar matrix.
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elstastins
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the extracellular matrix gets its elasticity by elastic fibers primarily composed of what?
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elstastins
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what elastic fiber is rich in glycine and proline, and the molecules are cross-linked by bonds between lysine residues?
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elastins
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what two fibers are embedding in a matrix of proteoglycans?
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collagen elastin |
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________ and _________ are enmeshed in a gel like network of proteoglycans, glycoproteins, and glycosaminoglycans.
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collagen elastin fibers |
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___________ also known as GAGs, are large carbohydrates with repeating disaccharide units.
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glycosaminoglycans
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in _______ the disaccharide repeating unit has one amino sugar, either n acetylglucosamine, or n acetylgalactosamine.
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glycosaminoglycans
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in glycosainoglycans, the other surgar is usallly a _____ acid like glactose or glucoronate.
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sugar
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what forms when glycosaminoglycans from the ECM covalently bond to proteins?
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proteoglycans
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proteoglycans have a number of GAG chains attached along the length of a _______ protein.
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core
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________ are usually integral compenents of the plama membrane with their core polypeptides embedded in the membrane.
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proteoglycans
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in many tissues, proteoglycans are present as __________ molecules.
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individual
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most _________ in the extracellular matrix exist only as components of proteoglycans.
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GAGs
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________ occurs both as a backbone of cartilage proteoglycans and as a free molecule.
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hyaluronate
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free _________ lubricates joints and facilitates cell migration.
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hyaluronate
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____________ glycoproteins are reinforced direct links between the extracellular matrix and the plasma mebrane
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adhesive
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adhesive glycoproteins have multiple domains to bind molecules in the ___________ and receptors on ____________.
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ECM membrane |
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what are the two most common types of adhesive glycoproteins to the ECM?
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laminins fibronectins |
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RNA transcribed from ______ gene is processed to produce many different mRNAs and thus many different variants of the adhesive glycoprotein.
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fibronectin
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what molecule has two large subunits linked near the C terminals by two disulfide bonds?
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fibronectin molecule
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the subunits of fibronectin are folded into a series of __________ domains.
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rodlike
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several domains of _________ subunits bind one or more ECM macromolecules. ex) of macromolecules: collagen, heparin, and fibrin. |
fibronectin
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_________ acts as a bridging molecule between cells and the ECM.
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fibronectin
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when __________ cells are grown on fibronectin, they adhere to it.
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migratory
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what component suggests it may guide embryonic cell migration due the enrichment of this component in the pathway?
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fibronectin
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what is the soluble form of fibronectin called that is found in the blood?
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plasma fibronectin
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how does fibronectin promote blood clots?
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because it has domains for binding fibrin (the blood clotting proteins). it can attach blood platelets to fibrin as the clot forms.
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_______ bind cells to the basal lamina. they are mainly found in the basal lamina.
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laminins
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laminins underlies epithelial cells, separating them from __________ tissues.
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connective
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what are the properties of the basal lamina?
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has a permeability barrier structural support all forms of basal lamina contain type lV collagen, proteoglycans, laminins, and other glycoproteins secretion enzymes can catalyze changes to lamina. |
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what kind of enzyme requires metal ions as a cofactor to alter the basal lamina?
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matrix metalloproteinases (MMPs)
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____________ degrade the extracellular matrix locally, allowing cells to pass through which allows for leukocytes to invade injured tissues.
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MMPs (enzyme)
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laminin can combine to form many different types of laminin. what is the consists in laminin to make this possible?
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three long polypetides alpha beta and gamma.
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what type of bond holds together the polypetides in the shape of a cross in laminin?
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disulfide bonds
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_____________ are a large family of cell surface receptors that bind to fibronectins or laminins. they integrate the cytoskeleton with the extracellular matrix.
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integrins
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the extracellular parts of the alpha beta subunits of integrin form what?
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biding sites
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many integrins recognize the ______ sequences in the extracellular matrix glycoproteins they bind to.
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RGD
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what part of integrin interacts with cytosolic proteins that link integrins to cytoskeleton?
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integrin tails
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what kind of cells attach to ECM molecules via focal adhesions?
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migratory and non epithelial cells like fibroblasts
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_____________ are found in epithelial cells. they contain a6b4 integrin. the integrins are attached to keratin in this case.
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hemidesmosomes
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one plakin called plectin attaches what to what?
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attaches keratin filaments to integrins.
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________ and __________ are transmembrane proteins that serve as a bridge between keratin and laminin.
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BPAG2 BPAG1 |
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________ play important roles in regulating cell movement and attachment.
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inegrins
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________ also interact with intracellular signaling pathways.
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integrins
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signals such as growth factors that lead to MAP kinase activation can induce integrin clustering. this is" ___________ ______ _____"
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inside out signaling
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the linker proteins in hemidesmosomes form a dense __________, connecting the integrins to the cytoskeleton.
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plaque
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integrins can also act as receptors that activate intracellular signaling. this is "_______ _____ _____"
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outside in signaling
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for most cells to grow in culture, they must be attached to a ________. if they can't attach to an ECM layer then they stop dividing.
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substratum
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_____ _____ growth involves activations of intracellular pathways following integrin clustering.
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anchorage- dependent
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what are the three kinases recruited to focal adhesions?
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focal adhesion kinase (FAK) Kindlins integrin linked kinase (ILK) |
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_________ complex stabilizes attachments of muscle cells to the extracellular matrix.
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dystrophin
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________ is an attachment structure at the surface of striated muscle.
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costamere
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mutations in the dystrohphin locus cause the most common type of __________ ______, duchenne muscular dystrophy (DMD)
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muscular dystrophy
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___________ interacts with a complex that includes integral membrane protein dystroglycan and the sarcoglycan-sarcospan complexes.
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dystrophin
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dystrophin also interacts with cytosolic proteins such as __________ and ___________
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dystrobrevins syntrophins |
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the ________ is a carbohydrate enriched zone at the periphery of animal cells (around the plasma membrane). its role is cell adhesion/recognition, protections of the surface, and creation of permeability barriers.
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glycocalyx
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________ in plant cells serve as a permeability barrier and structural framework.
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cell walls
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cell walls allow plants to withstand high _______ ________ exerted by the uptake of water.
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turgor pressure
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the plant cell wall is a network of what three components?
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cellulose microfibrils polysaccharides glycoproteins |
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the glycoproteins found in plant cell wall are called _________. the two main polysaccharies found in the plant cell wall is ____________ and ______
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extensins pectins hemicelluloses |
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________ is a long ribbonlike structure that is stabilized by hydrogen bonds. it is the most abundant organic macromolecule on earth.
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cellulose
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____________ are heterogeneous, each with a long linear chain of a single sugar ( either glucose or xylose) with short side chains that also contain surgars.
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hemicelluloses
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___________ are branched polysaccharides with backbones; the side chains have the same monosaccharides found in hemicellulose.
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pectins
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__________ are very insoluble polymers of aromatic alcohols found mainly in woody tissues. these components are localized between cellulose fibrils.
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lignins
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the __________ cell wall is a relatively thin, flexible structure that is formed while cells are still growing. it is a loosely organized network of cellulose, hemicellulose, pectins, and glycoproteins.
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primary
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first structure laid down for the cell wall from the inside out is the ______ _______
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middle lamella
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while shoots or roots are growing, _________ help cell walls retain pliability.
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expansins
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once cells have stopped growing, they add a thicker more rigid set of layers to the cell wall called ___ ____ ____
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secondary cell wall
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what two components are the main substances of the secondary cell wall?
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cellulose lignins |
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__________ are cytoplasmic channels through opening in the cell wall, allowing cytoplasmic continuity between two adjacent cells.
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plasmodesmata
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the __________ is thought to provide the cytoplasmic continuity between adjacent cells, allowing molecules to pass freely from one cell to the next. (in plant cell)
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annulus
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______________ are integral membrane glycoproteins used for cell to cell interactions.
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selectins
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________ cells interact primarily with other cells |
epithelial |
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___________ _________ are connective tissue cells that interact primarily with the matrix. |
mesenchymal derivatives |
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epithelial cells have three kings of cell to cell connections. what are they? |
adhesive tight gap junctions |
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what cell to cell connection do mesenchymal cells have? |
only adhesive junction |
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_______ junctions seal off the lateral surfaces so no leaking occurs between cells. This makes the cell polarized. |
tight |
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______ junction joins an actin bundle in one cell to a similar bundle in a neighboring cell. |
adherens |
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_________ join the intermediate filaments in one cell to those in a neighbor. |
desmosome |
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__________ anchors intermediate filaments in a cell to the basal lamina. |
hemidesmosome |
