Zachara_glycobiology Flashcards
(47 cards)
what are three essential properties of glycans
They are hydrophilic, hydrated, and often negatively charged
name three glycoconjugates in vertebrates
glycoproteins, glycolipids, and proteoglycans
what are 9 most common monosaccharide building blocks
glucose, galactose, GalNAc, GlcNAc, mannose, fucose, xylose, sialic acid, GlcA, IdoA
two other names for carbohydrates
glycans, sugars
a non-carbohydrate moiety
aglycone, covalently linked to the glycone
humans use glycolipids built exclusively on…
sphingosine, aka glycophingolipids
glycosaminoglycans
long repeating charged disaccharides that when linked to proteins become proteoglycans
a glycosaminoglycan that is rarely found bound to proteins
hyaluronan
a protein covalently modified by 1+ carbs
glycoprotein
glycocalyx
dense, sugary coat of cells/tissues
3 key roles of surface glycoproteins
cell adhesion, self/non-self recognition, pathogen invasion
the carbon in sugars which undergoes nucleophilic attack to become circularized
carbon 1 , or the anomeric carbon
T/F. All common monosaccharides in vertebrates have the same chirality - dextrarotatory (D) configuration
True
3 common modifications of sugar hydroxyl groups
sulfate, phosphate, or acetyl groups
difference between glucose and galactose
one single position of a bond at carbon 4
name 4 features which contribute to polysaccharide diversity
linear vs branched structure, alpha or beta configuration of anomeric carbon, aglycone attachment, and linkage position of each monomer to the next sugar
where do monosaccharides come from (3)
diet, salvage from degraded glycans, or derived from other sugars
two classes of sugar transporters
facilitated diffusion (GLUT) and energy dependent
how are carbohydrates added to nucleotides
through high energy phosphate bond, generate ATP analog. typical conjugation partners are UDP-, GDP-, and CDP
where are glycoconjugates synthesized
ER and golgi, sugar nucleotides pulled in from the cytoplasm by transporters
class of enzymes which catalize glycoconjugation
glycosyltransferases
these two residues terminate most glycoprotein and glycolipid glycons
fucose and sialic acid
influenza surface proteins and their connection to glycans
hemagglutinin, initiates flu infection by binding to cell-surface sialic acids to keep newly made virus from sticking to it, neuraminidase removes sialic acids on soluble mucins that would prevent cell-surface binding of invading virus
how does a cell get rid of unwanted extracellular glycoproteins and proteoglycans (2)
either shed from cell surface, or internalized and degraded in the lysosome
