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30 Cards in this Set
- Front
- Back
Complex carbs: def
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COVALENT complexes of sugars and proteins (proteoglycans and glycoproteins) or sugars and lipids (glycolipids)
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Glycosaminoglycans (GAGs): def
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Polymers of (-)disaccharide repeat units
ex. Heparin, hyaluronic acid |
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Proteoglycans: def
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Proteins with lots of GAG chains hooked on
Usually complex with long hyaluronic acid chain (a GAG itself) Almost all carbohydrate; not much protein |
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Glycoprotein
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Proteins with some oligosaccharide chains attached
Mostly proteins; not as much CH2O |
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Sulfation
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Makes OH groups on GAGs even more negative
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Proteoglycan structure
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Negative charges repel; "bottle-brush" molecular structure
Monomer = core protein plus lots of charged GAGs Associates with long hyaluronic acid chain = proteoglycan aggregates |
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Proteoglycan/GAG properties
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Slippery/slimy- high viscosity; lubricant for mucus, joints
Resilient- low compressibility "shock absorber"; food for synovial fluid in joins and vitreous humor of eye Around connective tissues, bone matrix, structural integrity |
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Heparin
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Anti-coagulant GAG
Stored in granules in mast cells that line arterial walls Released during injury; prevents runaway clotting? |
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Proteoglycan/GAG turnover
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Endocytosis, vesicle transport to lysosome
Un-degraded GAGs pile up in lysosomes-- debilitating skeletal/structural deformities |
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Glycoproteins: O-linked and N-linked
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N-terminal AA signal sequence directs to ER/Golgi where sugars added
O-linked: carbs hooked to -OH of Ser/Thr (blood group antigens) N-linked: carbs hooked onto NH2 of Asn (most glycoproteins; nature of carbs are molecular zip codes) |
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"High mannose" chains
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Mannose-P targets to lysosomes
Phosphotransferase enzyme and mannose-P receptor involved |
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"Complex" chains
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Targeted to cell surface or extracellular space
No mannose-P = outside cell |
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Functions of glycoproteins
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1. CH2O targets glycoproteins to lysosomes or PM (or secreted) - high mannose vs. complex GP
2. Determines half-life of circulating proteins 3. Cell surface recognition 4. Self vs. non-self recognition 5. Blood group antigens 6. Host-pathogen interactions 7. Extracellular matrix and mucins |
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Sphingolipids: def
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Lots in neurons and myelin
Long-chain amino alcohol (sphingosine) + FA + sugar head Sphingolipidoses: genetic defects in catabolism --> Mental retardation often present, early death |
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Sphingolipids: functions
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Structural components of NS membranes
Specialized membrane domains "lipid rafts" Lipid signaling molecules- 2nd messengers Ceramide (sphingolipid derivative) can initiate apoptosis |
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Inborn errors of sphingolipid metabolism
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Genetic mutations in enzymes or activator proteins
Lipid upstream accumulates --> pathology Depends on: Localization of accumulating lipid Prominence of lipid Turnover rate Physiological effects of accumulating lipid |
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Krabbe
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Cerebroside and psychosine build-up
Disruption of metabolic turnover destroys CNS myelin Psychosine is produced as a result of alternate (abnormal) catabolism; cerebroside is intermediate that builds-up |
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MLD
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Metachromatic leukodystrophy
Sulfatide build-up Disruption of metabolic turnover destroys CNS myelin |
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Gangliosides
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Sialic acid-containing glycolipids
Exclusively on cell surface, especially neurons Oligosaccharide head is receptor for glycosylated hormones Determinants of cell-cell recognition, and growth and differentiation Defective catabolism in Taye-Sachs disease |
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Tay-Sachs Disease
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Ganglioside build-up in neurons
Cherry red spot on retina is hallmark |
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Blood elements
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Sphingolipids antigens
A or B Dominant; antigen will be made if have one copy |
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Sphingomyelin
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Ceramide-P-Choline
Found in all cells Lots in myelin Defect in catabolism in Niemann-Pick A & B |
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Niemann-Pick A & B
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Build-up of sphingomyelin
Can't catabolize sphingomyelin |
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Degradation of GAGs
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Lysosomal enzymes (hydrolases) sequentially degrade GAGs
Defects in GAG degradation = mucopolysaccharidoses (un-degraded stuff piles up) |
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Hunter syndrome, Hurler syndrome
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Defective hydrolases that cleave GAG in lysosome
Mucopolysaccharidoses |
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Protein glycation
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Non-enzymatic condensation of aldehyde/ketone groups in sugars with amino groups in proteins
Get advanced glycation end-products (AGE) AGE leads to inflammation, atherosclerosis, diabetic pathology Depends on concentration of reactants |
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Ceramide
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Sphingosine + fatty acid
Base of sphingolipids |
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Cerebroside
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Gal-ceramide
Major myelin lipid |
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Sulfatide
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Sulfated cerebroside (sulfated gal-ceramide)
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I-cell disease
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Extracellular misrouting of acid hydrolases intended for lysosomes
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