1A.2 - Sugars Flashcards
What elements do all carbohydrates contain?
C, H and O.
Define ‘monosaccharides’.
The monomers from which larger carbohydrates are made.
Give 3 examples of monosaccharides.
Glucose, fructose and galactose.
What type of sugar is glucose?
A hexose sugar.
Define ‘hexose sugar’.
A monosaccharide with 6 carbon atoms in each molecule.
State the two isomers of glucose.
Alpha glucose and beta glucose.
Define ‘isomer’.
Molecules with the same molecular formula, yet their atoms are connected in a different way.
Which way round are the H and OH on alpha glucose?
H
OH
Which way round are the H and OH on beta glucose?
OH
H
What do 2 monosaccharides form when they join together? What type of reaction occurs to do this?
A disaccharide.
A condensation reaction.
What type of bond forms between 2 monosaccharides when a water molecule is released?
Glycosidic.
How is maltose formed?
By condensation of 2 glucose molecules.
How is sucrose formed?
By condensation of a glucose molecule and a fructose molecule.
How is lactose formed?
By condensation of a glucose molecule and a galactose molecule.
glucose + glucose –>
maltose
glucose + fructose –>
sucrose
glucose + galactose –>
lactose
Describe the Benedict’s test for reducing sugars.
1) Heat the sample with the Benedict’s reagent.
2) If the sample stays blue, then there is no reducing sugar present.
3) If the sample forms a brick red precipitate, then there is a reducing sugar present (and there will be solid particles suspended in the solution).
What are all monosaccharides?
Reducing sugars.
Give two examples of reducing sugars that are disaccharides.
Maltose and lactose.
If the concentration of a reducing sugar is higher then what will be happen in respect of the colour change?
It’ll go further.
