1.21 - Carbohydrates 1- monosaccharides and disaccharides Flashcards
What is the role of carbohydrates?
They are important for storing energy and form the cell wall in plants and fungi
What is a monosaccharide?
A single unit molecule of sugar
What are the two forms of glucose?
Alpha and Beta
What is glucose used for?
It supplies energy to the cells
What is the general formula for monosaccharides?
(CH2O)n
What is different between Alpha and Beta glucose?
The OH group on the left is below for Alpha whereas it is below for Beta
How are the carbons numbered in a monosaccharide?
Starting from the left and going clockwise
What is a disaccharide?
A molecule made form two monosaccharides
What type of bond join monosaccharides?
Glycosidic bonds
What type of reaction forms glycosidic bonds?
Condensation
How are glycosidic bonds named?
From the numbers of the carbon atoms it is between
What is a reducing sugar?
A sugar that can donate electrons to another chemical
What test is used for reducing sugars?
Benedict’s test
Describe the Benedict’s test
- Add Benedict’s reagent to the sample and heat for 5 minutes in a water bath
- A positive test shows colour changes from blue, to green, to yellow, to orange, and finally to brick red
- The higher the concentration of reducing sugars present will cause a change further through the chain of varying colours
What is more accurate than looking at the colour change during a Benedict’s test?
Weighing the precipitate that is formed after the test
