LECT 2 Flashcards
Commonly referred to as sugars and starches
CARBOHYDRATES
The word was given to this group of compounds because the molecular formula of simple carbohydrates could be written as
Cn(H2O)n making them hydrates of carbon
They are the storehouses of chemical energy
CARBOHYDRATES
CARBOHYDRATES are synthesized in green plants and algae through
photosynthesis
CARBOHYDRATES It can be classified into three groups:
- Monosaccharides
- Disaccharides
- Polysaccharides
The simplest carbohydrates
MONOSACCHARIDES
Generally have three to six carbon atoms in a chain, with a carbonyl group at either the terminal carbon, numbered C1 or C2
In most carbohydrates, each of the remaining carbon atoms has a hydroxyl
group
MONOSACCHARIDES
Monosaccharides with a carbonyl group at C1 are aldehydes called
aldoses.
Monosaccharides with a carbonyl group at C2 are ketones called
ketoses.
Glyceraldehyde is the
simplest aldose
Dihydroxyacetone is the simplest
ketose
Glyceraldehyde and dihydroxyacetone both have molecular formula OF
C3H6O3 so they are constitutional isomers
___ have the same molecular formula but a different arrangement of atoms
Constitutional isomers
___ is the most prevalent aldose
Glucose
MONOSACCHARIDES Is characterized by the number of carbons in its chain
A triose has three carbons
A tetrose has four carbons
A pentose has five carbons
A hexose has six carbons
1 2 3 4 5 6 7 8 9 10
MONO DI TRI TETRA PENTA HEXA HEPTA OCTA NONA DECA
FISCHER PROJECTION FORMULAS
FISCHER HAD NO WAY OF KNOWING WHAT THE CONFIGURATIONS (-) (+) GLUCERALDEHYDE WERE SO HE GUESSED.
The negative enantiomer was guessed to have configuration on the left (which we will now call as S) and was designated
L for latin (laevo)
The positive enantiomer was guessed to have configuration on the right (which we will now call as R) and was designated
D for latin (dextro)
A D monosaccharide has the OH group on the chirality center farthest from the carbonyl on the
right (like D-glyceraldehyde)
A L monosaccharide has the OH group on the chirality center farthest from the carbonyl on the
left (like L-glyceraldehyde)
The configuration of the chirality center farthest from the carbonyl group determines whether
a monosaccharide is D or L