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What are the four basic glycoconjugates?
Proteoglycan, glycoprotein, lipopolysaccharide, and glycolipid.
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Define proteoglycan:
- Proteoglycan: Sugars + protein, sugars dominant.
- Have glycosaminoglycans attached.
- Function as a component of the extracelluar matrix.
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Define glycoprotein: how are the carbohydrates attached to the protein? (hint: two linkages)
- Glycoprotein: Sugars + protein, protein dominant. found on outside of cell, part of cell to cell interaction. Found on outside of cell due to being only a large polar molecule.
- O-linked or N-linked.
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Understand the differences between the N-linked and the O-linked sugars.
- O-linked: amino acids involved are Ser or Thr
- N-linked: amino acid involed is Asn
- O and N are the molecules that link on the reducing end of the sugars.
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define lipopolysaccharides:
- Lipopolysaccharides: Sugars + lipids, sugars dominant.
- Function as a component of the outer membrane of gram-negative cells, target of antibodies.
- Membrane lipid with carbohydrate as hydrophobic head group.
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define glycolipids:
- Glycolipids: Sugars +lipids, lipids dominant.
- Function to provide energy and serve as markers for cellular recognition.
- Membrane lipid with carbohydrate as hydrophobic head group.
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Define glycoconjugate:
Glycoconjugate: Non-sugar compound with covalently attached sugars. Types of glycoconjugates include proteoglycan, glycoprotein, lipopolysaccharide, and glycolipids.
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What are the components of glycosaminoglycans? what sulfur-containing functional geoup is common in GAG?
Glycosaminoglycans: they are composed of repeating disaccharide units. The sulfur-containing functional group that is common in them is the sulfuryl group, esterified sulfate groups. The GAGs differ in glycosidic bonds and number of sulfuryl groups.
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What are the components of peptidoglycans?
Peptidoglycan: part of bacterial cell wall. Composed of alternating N-acetylglucosamine and N-acetylmuramic acid in (B1à4) linkage.
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What is a proteoglycan aggregate and what is its function?
Proteoglycan aggregates: enormous supramolecular assemblies of many core proteins all bound to a single molecule of hyaluronan. Glycoconjugate, supermolecular complexes. Core protein (aggrecan) + chondroitin sulfate + kerratan sulfate. Its function is to have binding sites for multiple extracellular matrix proteins -> matrix proteins bind to integrins -> cell migration, cell-cell adhesion, and/or signaling.
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Understand lectins: what they bind to, what kinds of materials the come from and how they function
Lectins: proteins that bind sugars with high specificity and affinity and ‘read’ the sugar code. Involved in cell recognition, cell adhesion, and signaling. Used as tools for labeling and carbohydrate detection.
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Describe the complexity associated with the analysis of carbohydrates: what are they used for?
- >20 different monosaccharides connected via various types of glycosidic bonds à billions of different oligosaccharides possible. Oligosaccharide sequences can be used as unique molecular recognition tags (biological bar code).
- Used as tools for labeling and carbohydrate detection.
- Involved in cell recognition, cell adhesion, and signaling.
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