Carbohydrates - MCAT

Glyceraldehyde

simplest aldose

Complex sugars

Cn(h2o)m

simple sugars

Cn(h2o)n

dihydroxyacetone

simplest ketone

D-fructose

D-glucose

D-galactose

D-mannose

D vs L (anomers)

D - first OH groupi s on the right

L - first OH group is on the left

enantiomers

differ at anomeric carbon!!!

Calculating steroisomers with same backbone

2^n (n=number of chiral carbons)

enantiomers of glucose

Diasteromer

same fam, same number of carbons, same ald/ke, but not identical

epimer

differs in configuration at only one carbon

four stereoisomers of an aldotetrose

with their corresponding L mirror images

hemiacetals/ketals

Tollens reagent

cyclic glucose

anomeric carbon

alpha-anomer

beta-enomer

mutarotation

spontaneous change of conformation

aldonic acids

oxidized aldoses into carboxylic acids

sucrose

glucose-a-1,2-fructose

lactose

galactose-b-1,4-glucose

maltose

glucose-a-1,4-glucose

cellulose

polymer of 1,4 linked beta-d-glucose

startch

polymers of alpha-d-glucose

example: amylose

amylopectin also has branches of a-1,6 bonds

iodine tests for the presence of start

benedicts reagent

detects reducing sugars, red precipitate forms

glucose oxidase

reduces glucose and only glucose

dilute nitric acid

reduces aldehyde and primary alcohol (c-6) to carboxylic acids in reducing sugars