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34 Cards in this Set
- Front
- Back
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What are the constituents of the extracellular matrix?
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1. Collagen
2. Glycoprotein 3. Proteoglycan |
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What are the modular building blocks of connective tissue?
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1. Collagen
2. Glycoproteins 3. Proteoglycans |
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ECM is basically a composite material of what two element?
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1. Semi-rigid linear elements (e.g.-collagens)
2. Flexible, space-filling elements (e.g.-glycoproteins and proteoglycans) |
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What are the two "themes" in ECM?
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1. Interstitial Connective Tissue
2. Basement membrane |
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What is the composite of polyproteins found in basement membranes?
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1. Fibrillar proteins
2. Glycoproteins 3. Proteoglycans |
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What are the two layers that make up the basement membrane?
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1. Basal Lamina
2. Reticular Lamina |
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What are the two layers of basal lamina?
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Lamina Rara (top layer)
Lamina Densa (bottom layer) |
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What are the components of intertitial connective tissue?
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1. Fibrillar component
2. Glycoproteins 3. Proteoglycans |
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What is the general structure of collagen?
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Three polypeptide chains (alpha chains) which are wrapped around one another to form a LEFT handed triple helix.
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What is the seqeunce found in the polypeptide chain of collagen?
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Gly-X-Y (where X is usually a proline and Y is usually a hyrdoxyproline)
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What happens when proline is in the Y position of the Gly-X-Y triplet?
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Prolyl hydroxylase will come in and convert it to 4-hydroxyproline.
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What happens when lysine is in the Y position of the Gly-X-Y triplet?
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Lysyl hydroxylase will convert it to hydroxylysine
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How would you read α1[I]?
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Alpha chain, number 1, from the Type I collagen family.
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How would you read [α1(I)]1 [α2(II)]2?
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A Type I trimer of 2 alpha 1 chains, and 1 alpha 2 chain.
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What occurs on the α chains have translation?
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Immediate posttranslational modification.
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Give an example of posttranslational modification in collagen synthesis.
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Prolines become modified to hydroxyprolines (by prolyl hydroxylase) or lysines become modified to become hydroxylysines (by lysyl hydroxylase)
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Is there any further modifications seen after immediate posttranslational modification?
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Yes. Hydroxylysine residues are further modified via glycosylation.
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Describe`
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Answers
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What is this and describe its structure.
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This is a fibril forming collagen. In "native" fibrils, the collagen molecules have repeat structures of 1 "hole zone" and 1 "overlap" zone with 1/4 staggared conformation.
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The fibrous backbone of ECM is also known as?
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Collagen
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Describe the organization of interstitial ECM in comparison to basement membrane ECM.
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Similar in organization
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Glycosylation of alpha chains occurs when?
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When you have hydroxylysine
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Which end does the assembly of collagen begin?
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At the carboxy end. Then proceeds to the amine end in zipper like fashion.
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The information needed for processing and assembly of collagen is located where?
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Inherent in the collagen structure.
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Where does procesing occur for collagen?
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Outside of cell.
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Within collagen, what is the enzyme responsible for INTRA-molecular crosslinks and where do they crosslink?
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Lysl-oxidase.
Crosslinks at between hydroxylysines. |
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What type of modification is VERY important in collagen structure?
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Post-translational modification.
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Structure of FACIT collagens allow for what?
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Globular domains allow for stability.
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Type IV collagens are used for what structures?
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Basement membrane.
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Describe the structure of Type IV collagens.
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Globular domains dimerize head to head on the carboxy terminus. These dimers then form a tetramer in the 7s region at the amino terminus. Leads to big network.
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How do you decrease the melting temperature Point of collagen?
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Decrease the number of hydroxyproline
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What are the cofactors required in collagen post-translational modification.
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Ascorbic acid and Iron
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How is Osteogenesis Imperfecta associated with collagen formation?
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A mutation leads to a frameshift leading to the loss of a cysteine in the carboxy end (meaning assembly is tough) causing non-incorporation to a trimer.
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Give two examples of post-secretory modification in collagen synthesis.
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1. Cleavage of N and C terminus propeptides.
2. Covalent cross-linking |
