sugars Flashcards
what is sugar a general term for?
monosaccharides and disaccharides
what are the simplest sugars?
monosaccharides
what elements do all carbohydrates contain?
C, H AND O
what type of sugar is glucose?
hexose- has six carbon atoms per molecule
what are the two types of glucose? ( isomers)
alpha glucose and beta glucose
what are isomers?
molecules with the same molecular formula as each other, but with the atoms connected in a different way
What is a disaccharide?
two monomers joined together in a condensation reaction.
what type of bond is formed between two monosaccharides in a condensation reaction?
glycosidic bond
name three disaccharides and the monosaccharides they are mad from?
Glucose + Glucose= Maltose
Glucose + Fructose = Sucrose
Glucose + Galactose = lactose
Whats the test for sugars? ( reducing or non reducing)
The Benedicts test
what does the Benedicts test actually test for?
whether a sugar is a reducing or non reducing sugar
what does reducing sugars include ?
all monosaccharides and some disaccharides
explain the Benedicts reagent test?
- add benedicts reagent( blue) to the sugar sample
- heat these in a water bath
- if a colored precipitate forms then a reducing sugar is present
- the further the colour the higher the concentration of reducing sugar( green - yellow- orange- brick red)
What is an accurate way to compare the amounts of reducing sugars in different samples?
filter the solutions and weigh the precipitate or use a colorimeter to measure absorbency of remaining benedicts reagent.
what do u do if the reducing sugars test is negative?
- Heat new sample with dilute hydrochloric acid
- neutralize sample by adding sodium hydrogen-carbonate-
- heat sample with benedicts reagent
- if it still stays blue there is no non reducing sugars present
- if colored precipitate forms a non reducing sugar is present
