2.1.2 Biological Molecules – Joining Monosaccharides Flashcards
(13 cards)
What is the name for a molecule made of two monosaccharides joined together?
A disaccharide
What type of bond is formed between two monosaccharides?
A glycosidic bond
Give three examples of disaccharide
Maltose, lactose, sucrose
Which disaccharide is a non-reducing sugar?
Sucrose
Which disaccharide is made when two alpha glucose molecules are joined together?
Maltose
What two monosaccharides make up sucrose?
Glucose and fructose
Which disaccharide is made when glucose and galalctose molecules are joined together?
Lactose
Which reagent (chemical) is used in the non-reducing sugar test?
Benedicts
In the non-reducing sugar test, what steps must be done before adding the Benedicts?
Boil the non-reducing sugar in hydrochloric acid (HCl), cool the solution and then add sodium hydrogencarbonate.
What is the purpose of boiling the non-reducing sugar with hydrochloric acid?
To break the bonds and separate the sugar into monosaccharides
What is the purpose of adding the sodium hydrogencarbonate?
To neutralise the solution and allow the Benedicts to work at a suitable pH.
Whats observed if Benedicts added to non-reducing sugar without boiling in HCl and adding NaHCO3
- Nocolour change and remains blue Benedicts colour
What are features of disaccharide?
- made of 2 sugar molecules
- bonded by glycosidic bond
- formed by condensation reaction (remove h20)
- broken by hydrolysis ( add h2o)
- sweet tasting
- soluble in water
