Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
25 Cards in this Set
- Front
- Back
|
Leukocyte adhesion deficiency II (LAD II)
|
-rare autosomal recessive syndrome associated with Bombay (hh) blood type
-patients have frequent infections b/c of defect in fucosylation --> white cells don't go where supposed to effectivey -cell to cell contact mediated by sugar --> necessary for blood cells to slow down & dock -MUTUAL INTERACTION B/W ENDOTHELIAL CELLS & WHITE BLOOD CELLS, both have receptors |
|
|
The characteristic bond through the anomeric carbon is called what?
|
Glycosidic linkage
|
|
|
How are mannose, glucose & galactose related?
|
stereoisomers of each other
|
|
|
Maltose Structure
|
two glucose in alpha 1-->4 linkage
|
|
|
Lactose Structure
|
galactose & glucose in beta 1-->4 linkage
|
|
|
Sucrose Structure
|
fructose & glucose
|
|
|
What is starch & what are the two forms & composition?
|
-storage form of carb in plant
-both homopolymers of glucose 1) Amylose: unbranced chain with alpha 1-->4 linkages 2) amylopectin: alpha 1-->4 linkages w/ alpha 1-->6 branches every 12 residues |
|
|
What is glycogen & what is the composition?
|
-carbohydrate storage in animals
-homopolymer of glucose -alpha 1-->4 linkages w/ alpha 1-->6 branches every 8-12 residues |
|
|
What is the structural composition of cellulose?
|
-homopolymer of glucose
-unbranched with beta 1-->4 linkages |
|
|
What are GAGs? Where are they found? What does their synthesis involve? What do they normally contain? What is an example of a GAG?
|
-long unbranched polysaccharides of repeating, anionic (neg. charged), disaccharides
-found in connective tissues -synthesis involves activated sugar (UDP) -normally contain sulfate -ex. Hyaluronic acid |
|
|
What is the name of a GAG chain covalently linked to a protein?
|
proteoglycan
|
|
|
Example of how proteins react chemically with carbohydrates?
|
-Glycated Hemoglobin (HbA1C) provides a "history" of glucose levels
|
|
|
Where do glycosylated proteins end up?
|
-glycosylation is for secreted proteins or domains facing extracellularly (or into lumen of ER)
-EXCEPTION OF O-GlcNac |
|
|
Which residues do O-linked glycosylations link to? Where are they glycosylated? What enzyme adds the first sugars? What adds the rest?
|
-Serine or Threonine
-glycosylated in Golgi -first sugar: N-acetylgalactosaminyl-transferase -rest of sugars: glycotransferases --> SPECIFIC ENZYME FOR EACH STOP OF SYNTHESIS -ONE AT A TIME PROCESS & add it directly to protein |
|
|
What residue do N-linked glycosylations link to? How are they added? Where does it happen?
|
-Asparagine
-Added first to dolichol phosphate (lipid carrier molecule) --> then transferred in tact to protein -generally done co-translationally in the ER |
|
|
What does tunicamycin do?
|
-selectively inhibits adddition of N-aacetylglucosamine-phosphate to dolichol phosphate
|
|
|
What happens to the glycosylations while the protein travels down from ER --> golgi? How do lysosomes break down glycosylations?
|
-they constantly are getting contents modified
-there are diseases associated with defective modifying enzymes -lysosomes use endo & exoglycosidases |
|
|
What do proteoglycans usually consist of?
|
-a core protein O-linked to a GAG
|
|
|
What are some examples of proteoglycans (3 of them)? Where can they be found?
|
-chondroitin sulfate
-heparin sulfate (the one that binds antithrombin to thrombin) -keratan sulfate -can be found in basement membrane, in knee cartilage acting as shock absorber |
|
|
What are glycoproteins recognized by?
|
lectins
|
|
|
What are 5 important aspects of protein glycosylation recognition?
|
1) assist protein folding in ER
2) intracellular proteins sorting/transport 3) first line of defense in immunity 4) determine half-life of serum proteins 5) direct cellular trafficking in vascular system |
|
|
Why are blood type O individuals more prone to Ulcers?
|
-because H. Pylori binds specific structures that look like blood type O sugars
|
|
|
Blood type is determined by what?
|
-glycosylation at end of carb chains of glycoproteins or glycolipids
|
|
|
How did the bird flu kill so many people?
|
mutated to recognized 2-->6 linkage rather than 2-->3 linkage so could infect humans
|
|
|
What glycosylation sends proteins to the lysosome?
|
M6P
|
