Carbohydrates 1 Flashcards
Carbohydrates Outline
Polyhydroxy aldehydes and ketones. Also called sugars. Synthesised in nature by photosynthesis. Simple and complex
Simple Sugars Outline
Monosaccharides, carbohydrates that can’t be converted to more simple sugars by hydrolysis. Eg glucose
Complex sugars outline
Simple sugars held together by glycosidic bonds. Can be hydrolysed to simpler sugars. Eg sucrose and cellulose
Glyceraldehyde Outline
Simplest aldose. 1 chiral center = 2 possible enantiomers (D-glyceraldehyde = R, L-glyceraldehyde = S)
Where does carbonyl C (1 containing functional group) go on Fischer projection
At top
Sugar Nomenclature
configuration (D/L)-carbonyl group(aldo/keto)-number of Cs(..hex/sept..)-ose
How to Distinguish Between D and L sugars
If OH on C furthest from carbonyl C os on right = D (dextorotory) . If OH on C furthest from carbonyl C is on left = L (levorotory). This is due to all stereo centers having opposite configurations
Realtionship between chiral centers and stereoisomers
2^n = possible stereoisomers. n = no of chiral centers
Anomeric Form Def
Configuration of carbohydrate ring. Alpha and Beta
Alpha Configuration Outline
OH on C furthest away from carbonyl group ,OH points down
Beta Configuration Outline
OH on C furthest away from carbonyl group. OH points up
Carbohydrate Epimers Def
OH is found on different locations in molecule
2 different carbohydrate sugars
Pyranose (chair like) and Haworth (ring). Pyranose is most common
Ketose sugars structures
Can form 6 and 5 membered ring structures
Function of hemiacteyl and hemiketyl
Intermediate in cyclisation of sugars. Open ring
Hemiacetyl/ Hemiketyl formtion
aldehyde/ketone + alcohol
