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BioChem: Carbohydrates

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What are carbohydrates (6 traits)?
-simple sugars
-polysaccharides
-stereoisomers
-surprisingly unreactive glucose
-reducing sugars
-polysaccharides
What is the formula for polyhydroxy aldehydes and ketones?
[C(H2O)]n
*n is greater than or equal to 3
What is the chemical formula for an aldose?
Draw it.
C3H6O3
What are monosaccharides?
-simple sugars that are water soluble
What are disaccharides?
-two monosaccharides linked by a glycosidic bond
-water insoluble
What are Oligosaccharides?
-contain up to 60 monosaccharides
What are polysaccharides?
-contain many monosaccharides
What are 4 different groups of saccharides?
-mono
-di
-oligo
-poly
What are geometrical isomers?
-differ in form by cis or trans.
-same empirical formula
-same molecules on each carbon (molecules)
Draw fumaric acid vs maleic acid
(cis and trans)
What is stereoisomerism?
-same empirical formula
-different orientation in space
How do Fisher projections work?
-draw all 4 bonds and label wedges for sticking out and slashed/dotted wedge lines for behind paper
-simplify by assuming vertical bonds behind and horizontal outwards
What are enantiomers?
-mirror image stereoisomers of one another but are non-superimposable.
What are diastereomers?
-stereoisomers that are NOT mirror image isomers
What are epimers?
-sugar diastereomers that differ in the orientation of one hydroxyl group
What molecule is used as the model for aldoses and ketoses?
-glyceraldehyde
What are some common aldohexoses?
-D(+)glucose
-D(+)Mannose
-D(+)Galactose
What is a common Ketohexose?
D(-)Fructose
What is the difference between aldehydes and glucose?
-aldehydes commonly auto-oxidize, whereas glucose doesn't
List three things that contribute to why glucose is so unreactive?
-they don't auto-oxidize
-do not form Schiff bases easily
-get two forms of glucose on crystallization (these forms can inter-convert in solution)
What is Schiff's base? And what is its formation?
-H2N--R''
How do you form a hemiacetal?
-aldehyde and alcohol
How do you get sugars from internal hemiacetals? Answer using a diagram with D glucose.
.
Draw Pyran and Furan.
Draw their sugars.
.
Draw sucrose and it's components.
.
Draw Lactose and its constituents.
.
What is a reducing sugar named in class? What does it reduce to?
-Beta-D-Glucopyranose
-D-Gluconic acid
What is the main "ingredient" in chitin?
-N-acetylglucosamine
Draw Chitin.
.

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