Carbohydrates Flashcards
(11 cards)
What is glucose?
A monomer of carbohydrate, simple sugar.
Has two isomers: Alpha and Beta Glucose
Disaccharide Reactions (3)
Glucose + Glucose = Maltose + Water
Glucose + Fructose = Sucrose + Water
Glucose + Galactose = Lactose + Water
What is Starch
Storage carbohydrate in plants
Long branched chains of α-glucose held together by glycosidic bonds
Properties of Starch (3)
- large insoluble molecule (osmotically inactive)
- Helical shape- More compact
- Branched - Glucose easily released for respiration
What is glycogen?
heavily branched polymer of α-glucose held together by glycosidic bonds
Stored heavily in liver and muscle tissues
Properties of Glycogen (2)
It is insoluble = osmotically inactive
Heavily branched = hydrolysed more rapidly to release glucose quicker
What is cellulose?
Polysaccharide that reinforces plant-cell wall and is a polymer of β-glucose
Properties of Cellulose (3)
-Insoluble = osmotically inactive
-Long straight chain
-Hydrogen bonds between adjacent chains (large number of H-bonds are strong)
Describe the Benedict’s Test (Reducing Sugars)
- Small amount of sample put in a test tube with same volume of Benedict’s
- Heat solution in a 95C water bath
- Blue= Negative, Brick red = Positive
Test for Non-reducing sugars
- Heat with Benedict’s and confirm negative result
- Hydrolyse substance with a dilute acid and neutralise with an alkali.
- Heat with Benedict’s Brick red precipitate indicates non- reducing sugar was originally present
how to use known sugar concentrations to determine unknown sugar concentrations
- Perform the Benedict’s Test with known sugar concentrations
- Use colorimeter to measure the absorbance value of each known concentration
- Plot graph of known concentrations against absorbance value and draw a line of best fit
- Repeat test with unknowns and use absorbance value to interpolate the concentration.
