1.2 Carbohydrates and monosaccharides Flashcards
What is the basic unit of a sugar called
Saccharide
What is a single monomer of sugar called
A monosaccharide
What is a pair of monosaccharides called after a condensation reaction, joining them
A disaccharide
What can more than 2 monosaccharides form after a condensation reaction, joining them
Polysaccharides
What are some properties of monosaccharides
They are sweet tasting, soluble substances, have the general formula (CH2O)n where n can be any number from 3-7
What are 3 examples of monosaccharides
Glucose, fructose, galactose
What does Glucose + Glucose make
Maltose
What does glucose + fructose make
Sucrose
What does glucose + galactose make
Lactose
What are the two isomers of glucose
α - glucose
β - glucose
What is the name for the test for testing for reducing sugars
Benedict’s test
What sugars are reducing sugars
All monosaccharides and maltose
What is a reducing sugar
A sugar that can donate electrons to another chemical
What is Benedict’s reagent
An alkaline solution of copper(II) sulfate.
Give three examples of Hexoses
Glucose, fructose, galactose
Give two examples of pentoses
Ribose
Deoxyribose
What is the formula of a disaccharide
C12H22O11
what is the test for a reducing sugar
add the food sample in a liquid or aqueous form to an equal volume of Benedict’s reagent. Heat the mixture gently in a boiling water bath for 5 mins. If a reducing sugar is present an orange-brown colour is formed.
what is the test for a non-reducing sugar
add the food sample to dilute hydrochloric acid. Heat the mixture gently in a boiling water bath for 5 mins. The HCL will hydrolyse any disaccharides. Slowly add some sodium hydrogencarbonate (NaHCO3) in order to neutralise the acid. Test with PH paper to check that the solution is alkaline. retest the solution by adding the food sample in a liquid or aqueous form to an equal volume of Benedict’s reagent. Heat the mixture gently in a boiling water bath for 5 mins. If a reducing sugar is present an orange-brown colour is formed.
what is the test for starch
place the sample in a test tube or add two drops of the sample to a spotting tile. add two drops of iodine solution and shake or stir. a positive test will go blue-black.
