BGM1002/L10 Carbohydrates I Flashcards
Give 3 functions of carbohydrates.
Storage/energy transport
Cell-cell communication/adhesion
Host-pathogen/symbiont interactions
Structural components
In DNA and RNA
What elements do carbohydrates consist of?
C, H, O
Some contain S and/or N
What is the empirical formula of carbohydrates?
(CH2O)n
How many hydroxyl groups do carbohydrates contain?
2+
What other names are given to carbohydrates?
Sugars
Saccharides
Glycans
What are the two simplest carbohydrates and how many carbons do they contain?
Glyceraldehyde
Dihydroxyacetone
3 carbons
How many stereoisomers does glyceraldehyde have?
2 (1 asymmetric carbon)
How many different groups are chirally active carbons attached to?
4
Which has more asymmetric carbons: aldoses, or ketoses?
Aldoses (+1)
Which carbon is referred to as C1 in a) aldoses and b) ketoses?
a) aldehyde
b) carbonyl
How many carbons do most sugar rings have?
4-5
What is a pyranose sugar?
A 6-membered ring (as it appears similar to pyran)
What configuration do sugar rings usually take?
Non-planar ‘chair’ configuration
What two orientations can substituents on ring C atoms hold?
Axial or equitorial
What is the difference between alpha and beta rings?
Alpha - C1 and C5 have same stereochemistry
Beta - C1 and C5 have different stereochemistry
What is the difference between D and L stereoisomers?
L has left-handedness
D has right-handedness
What isomer form do most sugars take?
D-form
Define epimers.
When asymmetric carbon 2, 3 or 4 is in a different configuration to glucose, resulting in a different sugar
Define oligosaccharide.
A sugar of 2-10 monosaccharides
Define polysaccharide.
A sugar of 10+ monosaccharides
What bond forms between monosaccharides?
Covalent glycosidic bond
What groups do glycosidic bonds form between?
Hemiacetal and hydroxyl or non-sugar hydroxyl
-NH
-SH
What is an alpha configured glycosidic bond?
C1,4 bond in alpha molecules
