BCM11 Flashcards
(33 cards)
what are carbohydrates?
carbon compounds with multiple hydroxyl groups
what is the formula for carbohydrates?
Cn(H2O)n
what are the 2 types of monosacharides?
aldoses and ketoses
how many enantiomers does glyceraldehyde have?
has a single chiral centre so 2
what is the iupac name for glyceraldehyde?
2,3-dihydroxypropropanal
what is an aldose?
simple monosaccharide with one aldehyde group
what is an example of an aldose?
glucose
draw glucose in straight chain
-
what determines whether a monosaccharide is in d or l form?
absolute configuration of last chiral carbon fruthest from aldehyde or keto group
if its on the righ = d frorm
left = L
what are diasteromers?
same atoms not mirror images
what are epimers?
pairs of sugars differing in configuration of a single carbon
eg. differ only in c2
how do you calculate number of steroisomers?
2^n-2
n= no of carbons in aldose
n= no of chiral centres
how do you calculate number of enantiomer pairs?
2n^-1
n= number of chiral centres
what happens in aldose hexose if you swap conformation on c5?
get L configuration of sugar
= different name
D glucose -> L idose
what happens to monsaccharides in solution?
they form cyclic ring structures
what two molecules does D glucose form in solution?
alpha - D- glucopyroanose
beta - D - glucopyranose
what are the alpha and beta forms known as in relation to each other?
anomers
what is the alpha beta ratio?
1:2
in a glucose solution what % will be in open chain form?
what does alpha d glucopyranose look like?
Hydrogen pointed upwards on first carbon (carbon which was aldehyde)
what does beta d glucopyranose look like?
hydrogen pointing down on first carbon
how does d manose differ from d glucose?
c2 carbon epimer
how does d galactose differ from d glucose?
c4 epimer
how does pyranose ring form? mechanism
nucleophillic attack of the lone pair of the oxygen attatched to the c5 carbon on the c1 carbon