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97 Cards in this Set
- Front
- Back
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What is the most common monosacaccharide?
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hexoses
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What distinguishes an aldoses?
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C==O...on end
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What is distinguishing feature of a ketose?
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C==O...in middle
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What is second in importance to hexoses?
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pentoses
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Explain trioses, tetroses, pentoses, and hexoses?
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distinguishes the number of carbons in an aldose or ketose monosaccharide
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Where are pentoses found?
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in nucleic acids
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How do you figure out the possible number of stereoisomers of a monosaccharide as a function of it's chiral centers?
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2^n (n = # chiral centers)
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By convention, the stereisomers of monosaccharides are classified as D or L based on the configuration of what?
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The chiral carbon farthest from the carbonyl group, with reference to D/L glyceraldehyde
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In nature almost all monosaccharides are what isomers?
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D (though there are some L sugars)
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What group is D-glyceraldehyde in?
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3 carbon D-Adlose
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What groups is Dihydroxyacetone in?
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3 carbon D-Ketose
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Which group is D-ribose in?
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5 carbon D-Aldose
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Which group is D-glucose in?
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6 Carbon D-Aldose
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Which group is D-Fructose in?
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6 carbon D-Ketose
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Which group is D-mannose in?
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6 carbon D-aldose
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Which group is D-Galactose in?
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6 Carbon D-Aldose
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Glyceraldehyde is a what?
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aldose, triose
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Ribose is a what?
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aldose, pentose
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Glucose, Mannose, and Galactose are what?
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aldoses, hexoses
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Dihydroxyacetone is a what?
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ketose, triose
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Fructose is a what?
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ketose, hexose
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Rib
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ribose
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Glc
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glucose
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Man
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mannose
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Gal
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galactose
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Fru
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fructose
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What are epimers?
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sugars that differ only in their configuration at one chiral center (when compared to glucose, not when compared to eachother) They are epimers at the #C of wherever the difference may occur.
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Glucose configuration?
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CHO
! H-C-OH ! HO-C-H ! H-C-OH ! H-C-OH ! CH2OH ...but he says he will never ask structure |
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What do sugars spontaneously do in solution?
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cyclize to form hemiacetals of hemiketals...hemiacetals have one H group off of C while hemiketals do not (only 2 R groups) see chpt 7 slide 22 for clarification
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Pyranose vs Furanose?
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pyranose = 6 member ring
furanose = 5 member ring, less stable |
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What is an anomer?
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monosaccharides differing only in their configuration at the hemiacetal/hemiketal carbon (so they occur in pairs)
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What are the two formations of anomers?
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alpha and beta...alpha has hydroxy group on bottom and beta has the hydroxyl group on top
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What is mutorotation?
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interconversion of anomers (in aqueous solution) (at equilibrium, there may also be some linear molecules)
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What is a Haworth perspective?
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formulas that show the stereochemistry of the ring forms of monosaccharides (2 conformations)...includes pyranoses and furanoses
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The 2 conformations of 6 member rings? Which one is favored?
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chair and boat...boat is favored
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What is N-acetyl-beta-D-glucosamine?
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one of the many derivatives of hexose
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What makes most monosaccharides reducing sugars?
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the carbonyl group can be oxidized
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When a disaccharide is formed...what needs to occur for the it to be considered a reducing sugar?
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the anomeric carbon of at least one of the monomers remains free...anomeric is the hemiacetal group...so just look for the hemiacetal group (looks like they need to connect 1 to 4)
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When a disaccharide is formed...what needs to occur for it to be considered a nonreducing sugar?
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if both of the anomeric carbons are part of the O-glycosidic bond (looks like they are nonreducting if they are not connecting 1 to 4)
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Maltose monomers and activity?
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Glc-Glc (reducing)
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Lactose monomers and activity?
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Gal-Glc (reducing)
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Sucrose monomers and activity?
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Fru-Glc (non-reducing)
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Trehalose monomers and acivity?
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Glc-Glc (non-reducing)
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Shorthand and activity for maltose?
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Glc(a1-->4)Glc...reducing
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Shorthand and activity for lactose?
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Gal(B1-->4)Glc...reducing
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Shorthand and activity for Sucrose?
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Fru(B2<-->1a)Glc or
Glc(a1<--2B)Fru...non-reducing |
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Shorthand and activity for Trehalose?
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Glc(a1<-->1a)Glc
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Polysaccharides are also known as what?
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glycans
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What are the differences between homo and heteropolysaccharides?
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homo are all the same units (ex. all glucose)...Hetero are 2 or more different substituents (often alternate)
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4 types of polysaccharides?
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1. storage homopolysaccharides
2. structural homopolysacch- 3. Structural heteropolysacc- 4. Glyconjugates (information carriers) (Carbohydrate and other molecule..like protein, lipid, etc) |
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What are storage homopolysacch.s?
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food molecules stored in cell
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What are structural polysacch.s?
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stay in cell as framework
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What kind of polymer (polysaccharide) are amylose and amylopectin?
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starch
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Amylose is what type of polysaccharide?
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homo
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Amylopectin is what type of polysaccharide?
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homo
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For starch in plants anomeric carbon is in what conformation?
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the alpha conformation
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Describe structure of amylose and linkage?
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unbranched glucose polymer...(a1-->4 linkage)
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Describe structure and linkage of amylopectin?
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a1-->4 linkage, branched (every 24-30 residues) using a1-->6 linkage
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Glycogen is found where?
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animals
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Describe structure and linkage of glycogen?
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a1-->4 linkage branched every 8-12 residues using a1-->6 linkage
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Glycogen, starch (amylose and amylopectin) are what types of glycans?
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storage
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Chitin and cellulose are what type of glycans?
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structural
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What is the most abundant polysaccharide in nature? Where is it found?
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cellulose...in plants' cell walls
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Cellulose is an unbranched polymer of what? Which configuration is the anomeric carbon in?
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glucose monomers...the beta
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What is the result of cellulose's anomeric carbon being in the beta configuration?
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these polylmers are strong, straight chains
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Cellulose are straight chains wht is amylose and why?
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tightly coiled, compact helices...because it is in the alpha configuration
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Most animals have what to digest amylose? What can they not digest? What are the exceptions?
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most have alpha-amylase...cannot digest cellulose....important exceptions are cows and other ruminants
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What is the 2nd most abundant polysaccharide?
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chitin
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Where is chitin found?
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principal component of exoskeletons of lobster, insects, etc.)
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Chitin structure?
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unbranched polymer of N-acetylglucosamine
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Storage polysaccharides have the anomeric carbon in what configuration?
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alpha
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Structural homopolysacchs. have the anomeric carbon in what configuration?
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beta
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Cellulose is made of what monomers?
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glucose
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The advantages of storing sugars as polymers rather than monomers?
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1. polysacchs. are insoluble and do not contribute to osmotic pressure
...so we store less polysacchs.....without glycogen glc conc. would increase and lead to cell explosion...so more advantageous to store as glycogen |
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What is the advantage of branching in polysaccharides?
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makes energy more accessible...quicker degradation by enzymes that attack only non-reducing sugars...
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5 main structural features of peptidoglycans?
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(strucutral heteropolymer..."peptides,carbs")
1. Alternating monosaccharide (repeating disaccharides) 2. Peptide-cross-linked linear polysaccharides 3. Hydrolyzed by lysozome (in tears) - prevents bacterial infections in eyes 4. Penicillin and related antibiotics prevent synthesis of cross-links (so you can still make polysaccharide chains) 5. Peptide links between disaccharides so polysaccharides in one direction and peptides in the other |
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4 structural features of glycosaminoglycans?
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1. repeating disaccharides
2. with an amino side group 3. no cross-links-different then peptidoglycans 4. components of gel-like extracellular matrix-not parts of cell walls like peptidoglycans these are between cells |
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4 examples of glycosaminoglycans?
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1. hyaluronate
2. chondroitin sulfate 3. keratan sulfate 4. heparin |
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Hyaluronate function?
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viscous LUBRICANTs in synovial fluids (joints)...vitreous humor
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Chondroitin function?
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confers tensile STRENGTH on cartilage, tendons, ligaments, aorta walls
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Keratan sulfate function?
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in the cornea, cartilage, bone, horn-like structures...like chondroitin this is involved with strength
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heparin function?
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natural anticoagulant
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The key structural features of glycoconjugates and 3 examples?
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All are information carriers (markers on cells)...All consist of Oligosaccharides +
1. proteoglycans 2. glycoproteins 3. glycolipids |
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Key structural feature of proteoglycan?
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1 or more glycosaminoglycan chains bound to a core protein
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Strucural and functional aspects of proteoglycans?
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1. found on cell surface or in extracellular matrix...major component of connective tissue
2. the glycosaminoglycan portion is often the main site of biological activity |
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Components of glycoproteins?
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protein + carbohydrate...so protein + 1 or more oligosaccharides
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The difference between teh carbohdrate components in glycoproteins vs. proteoglycans?
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the oligosaccharides found in glycoproteins are smaller and more structurally diverse than proteoglycans
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Where are glycoproteins found?
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On the cell surface or secreted into extracellular matrix
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Examples of glycoproteins?
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Immunoglobulins, various hormones (FSH, LH, TSH)
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The glycolipids (glycolipids and lipopolysaccharides) have what instead of protein/peptide?
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lipid
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Structure and function of glycolipid?
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1. lipids covalently bond to oligosacchs.
2. on the outer surface of the plasma membranes 3. Often binding sites for proteins (eg. blood group determinants) |
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Glycolipids are information what?
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carriers
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Glycolipids determine what?
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blood type
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Lipopolysaccharides structure and function?
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1. dominant surface feature of gram-negative bacteria (e.coli, salmonella)
2. prime targets of antibodies |
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Where are blood group determinants found?
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on surface of cell
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What is a Lectin?
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not a carb...it is a protein that binds to carbs...proteins that specifically and strongly bind carbohydrates...found in all organisms
-Serve a wide variety of CELL-CELL RECOGNITION AND ADHESION PROCESSES |
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One type of Lectin?
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selectins
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