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26 Cards in this Set
- Front
- Back
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How many monosaccarides are in a polysaccaride?
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10 or more
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What is the name for a carbohydrate with 2-10 monosaccarides?
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Oligosaccaride
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What holds oligosaccarides together?
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Glycosidic linkages
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What is described:
"Stereoisomers that are exact mirror images" |
Enantiomers
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What is described:
"Stereoisomers that are NOT exact mirror images" |
Diastereomers
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What is a special class of diastereomers (NOT mirror images) that differ in configuration at only one asymmetric center?
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Epimers
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What is a special feature of Enantiomers?
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Optically active
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Does alpha go up or down? Beta?
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Alpha down, beta up
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What is it called when you go between the alpha and the beta anomers? How do you do it?
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Called mutarotation. Requires the ring to be opened, the confirmation flipped, and then the ring closed.
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How do you recognize a glycosidic bond? Anything that has a glycosidic bond is called a ___________
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-O-C-O-C
-glycoside |
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How do you form a glycoside (energetically unfavorable)?
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Must use an activated monosaccaride donor substrate, such as GDP glucose.
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What enzyme is needed to form lactose in the mammary gland during lactation?
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Galactosyltransferase (a glycosyltransferase)
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What are the characteristics of sialic acid?
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-Large sugar
-Negatively charged |
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How do you form N-acetylglucosamine?
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-Start with F-6-P.
-Transamidation (taking amide group from glutamine) -Rearrangement to Glucosamine-6-P -Transfer an acetyl group on from AcCoA forming N-acetylglucosamine 6-P -Mutate to N-acetylglucosamine 1-P -Form the activated donor UDP-N-acetylglucosamine (also epimerases to UDP-N-acetylgalactosamine) -Connect it to a protein! |
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Is a glycosidic connection to asparagine N-linked or O-linked? to serine?
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Asparagine is N-linked!
Serine is O-linked! |
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What is the function of salivary mucin?
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-Protect stomach from its acids
-Slippery to line ducts |
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What is the difference between O-linked saccaride chain formation with serine and N-linked sacccaride chain formation
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O-linked adds one saccaride at a time, directly onto the protein. N-link transferrs the whole unit en bloc
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What is the function of a glycosidase? a glycosyltransferase?
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A glycosidase takes off sugars. A glycosyltransferase puts sugars on!
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Once the whole unit of sugars is transferred onto the protein (N-linked with asparagine), what happens if the protein was folded incorrectly?
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-If the protein was folded incorrectly, the glucose residues will stay on and the protein will be degraded.
-If the protein was folded correctly, then the glucose will come off and the protein will be allowed to go to its target. |
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How do lysosomal enzymes know to go to the lysosome?
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Mannose 6-P is the residue that gets the enzyme to the lysosome. The enzyme that starts this process is called phosphotransferase and it's defective in I-cell disease.
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What is I-cell disease?
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Phosphotransferase is the defective enzyme. Without it, lysosomal enzymes don't get to the lysosome. I-cell disease is a disorder in which mannose 6-P isn't formed and can't guide lysosomal enzymes to the lysosome. The end result is lysosomal enzymes in the extracellular medium and inclusions that can't be broken down.
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What is the important emzymes that makes the blood types?
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Glycosyltransferases. These enzymes are SO specific that they only transfer specific sugars. Blood types only differ by one sugar.
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What is the function of glycosidases?
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Glycosidases break down carbohydrate chains by hydrolysis. This is broken in Tay-Sachs and Sandhoff diseases.
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What are gangliosides?
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Gangliosides are carbohydrate chains that always contain sialic acid. Deficiencies in glycosidases cause build up of gangliosides, as in tay-Sachs and Sandhoff diseases.
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What is Tay-Sach's disease? Sandhoff disease?
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Deficiencies in glycosidases. Cause gangliosides to build up, particularly in neurons.
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How can a glycoside help to excrete xenobiotics or drugs from the body?
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UDP glucose (an activated monosaccaride donor) is converted to UDP-glucuronate. This is highly polar and charged so it's very water soluble. It is attached to a substance that the body wants to eliminate and is secreted in the urine. On the way, UDP is conserved.
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