Shared Flashcard Set

Details

Sugar Catabolism and Biosynthesis
EXAM 2
48
Medical
Post-Graduate
08/30/2010

Additional Medical Flashcards

 


 

Cards

Term
what are the three molecules that interconvert between each other?
Definition
glucose6p-->fructose6p-->mannose6p
Term
what is an essential feature of the glycoprotein structure?
Definition
covalent linkage
Term
what is the structure of N-linked glycoproteins?
Definition
two N-acetylglucosamines (GlcNac) and three mannoses.
Term
what is the function of phosphoglucose isomerase?
Definition
converts glucose to fructose
Term
what is the function of phosphomannose mutase?
Definition
converts mannose 6 phosphate to fructose 6p
Term
what is aldose-ketose isomerization?
Definition
moves double within same molecule w/o net change in the oxidation state of the molecule.
Term
what is type 1 CDG associated with?
Definition
deficiency in phosphomannose mutase 2
Term
what is type 1b CDG characterized by?
Definition
phosphomannose isomerase deficiency
Term
what does the basic defect of CDGS appear to be
Definition
synthesis of processing of N-linked oligosaccharides
Term
this is used as a sensitive indicator to identify CDG
Definition
glycosylation state of serum transferrin
Term
what is an indicated by transferrin
Definition
altered electrophoretic mobility of unusual isoforms
Term
what is present in O-linked glycoproteins
Definition
fucose, sialic acid, and N-acetyl galactosamine
Term
GDP mannose is converted to GDP fucose releasing what
Definition
NADH
Term
decarboxylation of of UDP-glucuronic acid yields what (UDP Glu->UDP Glucuronic->?)
Definition
UDP-xylose
Term
what is UDP xylose necessary?
Definition
synthesis of proteoglycans
Term
this leads to formation of amino sugars and sialic acids
Definition
transamidation of sugars
Term
the A allele encodes what?
Definition
N-acetylgalactosamine
Term
B allele encodes for
Definition
galactosyltransferase
Term
the O allele encodes for
Definition
an inactive protein
Term
symptoms of hereditary fructose intolerance
Definition
hypoglycemia, hyposphosphatemia, hypermangnesemia
Term
In hereditary fructose intolerance, what is interconverted?
Definition
fructose 6p and glucose 6p interconvert
Term
deficiency in aldolase B leads to?
Definition
low ATP and phosphate depletion
Term
dietary fructose is converted to fructose 1p by what enzyme
Definition
fructokinase
Term
how is fructose intolerance treated?
Definition
complete elimination of all sources sugar
Term
essential fructosuria is a deficiency in
Definition
fructokinase
Term
consumption of fructose from an individual with aldolase B deficiency results in
Definition
accumulation of fructose 1-phosphate and depletion of ATP
Term
when glucose concentration in the lens is high, this enzyme converts some of it to sorbitol
Definition
aldose reductase
Term
sorbitol can be converted to fructose by what
Definition
polyol dehydrogenase
Term
accumulation of sorbitol in the eye leads to increased osmolarity of the lens. what does this cause
Definition
aggregation and denaturation of the crystallins
Term
what is a catract?
Definition
changes in the structural organization of crystallins w/increased light scattering
Term
when aldolase reductase is greater than the activity of polyol dehydrogenase, what does that cause
Definition
accumulation of sorbitol leading to catarcts
Term
when aldolase reductase is greater than the activity of polyol dehydrogenase, what does that cause
Definition
accumulation of sorbitol leading to catarcts
Term
interconversion of glucose and galactose requires formation of
Definition
UDP linked sugar
Term
deficiency in this enzyme causes a relatively mild form of galactosemia
Definition
galactokinase
Term
how does excess galactose play a role in central nervous system damage?
Definition
galactose is reduced to galactitol causing accumulation in the lens.
Term
deficiency of this enzyme causes severe galactosemia
Definition
uridyltransferase
Term
this enzyme deficiency can cause both forms of galactosemia
Definition
UDP glucose 4 epimerase
Term
what forms glucuronic acid
Definition
oxidation of UDP glucose
Term
what is the major difference between UDP glucose and UDP glucuronic
Definition
HOCH2-->COOH
Term
what is the central step in bilirubin exretion?
Definition
conjugation w/glucuronic acid by UDP-glucuronyltransferase
Term
congenital familial non hemolytic jaundice results from a deficiency of
Definition
UDP gluronyltransferase
Term
can humans convert glucuronic acid to ascorbic acid?
Definition
NO
Term
what is essential for sorting of the enzymes to lysosomes
Definition
addition of a phosphate group to mannose in position 6
Term
what is mucolipidosis II (I cell) disease characterized by?
Definition
deficiency in N-acetylglucosamine phosphotransferase
Term
what happens to fibroblasts in I cell disease
Definition
dense inclusion bodies-lack of lysosome function
Term
what is mucolipidosis III due to?
Definition
reduced GlcNac phosphotransferase
Term
what is the function of phosphomannose isomerase
Definition
fructose 6p to mannose
Term
what does the Hgene code for in the ABO blood group systems?
Definition
fucosyltransferase
Supporting users have an ad free experience!