Carbohydrates Flashcards
functions of carbs>
forms what when binded to proteins and lipids?
energy source and energy storage
structural component of cell walls and exoskeletons
informational molecules in cell-cell signaling –The “Sugar Code”
can bind to:
proteins: forms glycoproteins and proteoglycans
lipids: glycolipids
empirical formula of monosaccharrides?
(CH2O)n
3=
How to know D or L?
review slide
look at OH group when aldehyde is on top (and pointing away)
right = detro
left = levo
*not same as R/S
general number of stereoisomers?
# stereoisomers = 2^n (where n = # of chiral carbons)
what is an epimer?
2 sugars that differ only in configuration of one chiral atom
general number of epimers for monosaccharides?
of epimers = (# of chiral C) - 1
diff between hemi acetal and hemiketal?
refer to diagram
hemiacetal: aldehyde = alcohol
what is a mutarotation?
conversions between alpha and beta anomers
what is the anomeric C?
“reducing end” = important property of sugars
C linked to the oxygen on right of ing
names of cyclic forms of monosaccharides?
5 C ring = furan ring
6 C ring = pyran ring
what is fehling’s reaction?
used to determine glucose levels in blood or urine. oxidizing monosaccharides to give carboxylic acid
not accurate. should measure hydrogen peroxide instead
linkage in disaccharide
glycosidic linkage
types of polysaccharides?
- homopolysacc: energy storage and structural
- can be unbranched and branched - heteropolysacc: cellular and structural
- can be two or more monomers
- can be branched or unbranched
describe starch as storage polysaccharide
main storage homopolysaccharides in plants
starch is a mixture of 2 homopolysaccharides
- amylose (unbranched)
- amylopectin (branched)
links in amylose and amylopectin and glycogen??
amylose: alpha 1-4
amylopectin: alpha 1-4, but branches are alpha 1-6 (branch is every 24-30 glucose residues)
glycogen: alpha 1-4, but branches are alpha 1-6 (branch is every 8-12 residues)
structure of cellulose?
- fibrous, water insoluble polymer
- in plant cell walls
- most abundant polysacc in nature
glucose monomers form beta 1-4 links
-H bonds form adjacent monomers. chairs are 180 to one another = max H bonds
roles of mono and oligosacc once added onto proteins?
- Cell-cell interactions, through special receptor proteins (e.g. Lectins)
- Stabilize proteins against degradation, hence most surface proteins
- Mechanisms in proper folding of protein, eg. Glycophorin
- Protein targeting signals for intracellular proteins
2 types of heteropolysaccharide linked additions?
N-Linked oligosaccharides
O-Linked oligosaccharides
what lipids are modified with oligosaccharides?
sphingolipids and phospholipids
