1.2 Carbohydrates Flashcards
What is a monosaccharide?
An individual sugar monomer from which carbohydrates are made (reducing).
Name 3 monosaccharides.
- Galactose
- Glucose
- Fructose
What is a disaccharide?
A sugar formed from two monosaccharides
joined by a glycosidic bond
in a condensation
reaction.
Maltose?
α-glucose + α-glucose (reducing)
Lactose?
α-glucose + galactose (reducing)
Sucrose?
α-glucose + fructose (non-reducing)
Which type of covalent bond is found in carbohydrates?
Glycosidic Bond.
Name the two isomers of glucose.
α-glucose and β-glucose.
Where is the OH on C1 in α-glucose?
Below the ring.
Where is the OH on C1 in β-glucose?
Above the ring.
What method can be used to separate a mixture of monosaccharides and identify the individual components?
Chromatography.
Test for reducing sugars.
- Add Benedict’s Reagent to a sample solution in a test tube.
- Heat the test tube in water bath for 5 minutes.
+ve result: coloured precipitate will form as copper (II) sulfate is reduced to copper (I) oxide which is insoluble in water (blue to green, yellow, orange, brick-red)
Test for non-reducing sugars.
- Add dilute hydrochloric acid to the sample and heat in a water bath that has been brought to boil
- Neutralise the solution with sodium hydrogen-carbonate (use litmus paper to check that it has been neutralised)
- Add Benedict’s Reagent to a sample solution in a test tube.
- Heat the test tube in water bath for 5 minutes.
+ve result: coloured precipitate will form as copper (II) sulfate is reduced to copper (I) oxide which is insoluble in water (blue to orange, brick-red)
What is a polysaccharide?
Polysaccharides are polymers formed by many monosaccharides joined by glycosidic bonds in a condensation reaction to form chains.
Name 3 polysaccharides.
- Cellulose
- Starch
- Glycogen