Chapter 7 Carbohydrates Flashcards Preview

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Flashcards in Chapter 7 Carbohydrates Deck (17):
1

# 1 Why are monosaccharides appropriately named carbohydrates?

Cn(H2O)n

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# 2) Why are monosaccharides soluble in water but not in non-polar solvents?

Soluble in water, because of the presence of multiple hydroxyl groups.

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#3) What are the naming conventions for monosaccharides?

aldoses vs. ketoses. and length

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#4) The word "Chiral" is derived from the greek word meaning "hand." How does this relate to the structure of carbohydrates?

Carbohydrates, excluding dihydroxyaetone, are chiral. each molecule has 2^n stereoisomers. Where n = the number of carbons - 2

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# 5) How many D-isomers would an aldopentose have? How many total isomers?

2^3

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#6) Is galactose and epimer of mannose

No

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# 7) In an aqueous solution of D-glucose, why will there always be a very small amount of the linear form of the monosaccharide?

The ring form is more stable and is formed readily

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Cyclization and stereo-isomerism

when a saccharide cyclizes, there is a new chiral center that is generated

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Anomers

isomeric forms of a monosaccharide that differ only in their configuration about the hemiacetal or hemiketal carbon

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pyranoses

6 membered rings

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furanose

hemiketal 5 membered ring

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# 10) Why is phosphorylation of sugars beneficial to a cell?

1) Traps sugars inside of the cell 2) activates sugars for chemical processing 3) Sugar phosphates are relatively stable

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A sugar can only be oxidized in its...

linear form. In a polysaccharide, the anomeric carbons not involved in the glycosidic bond are non reducing.

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Q # 15 What are the structural and functional differences between homopolysaccharides and heteropolysaccharides?

Homo- one anomeric species; hetero - more than one anomeric species

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Starch

contains long unbranched chains of D-glucose connected by (alpha 1->4) linkages;

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Amylopectin

contains long branched chains of D-glucose; connected by (alpha 1->4) linkages; branch points are every 24 to 30 residues with (alpha 1->6) linkages

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Glycogen

main storage polysaccharide in animals; ( alpha 1->4) linkages with (alpha 1->6) branched linkages on every 8-12 residues; each glycogen molecule has n+1 reducing ends;

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