Carbohydrates Flashcards
Which monomers make carbohydrates?
Monosaccharides
Name 3 monosaccharides:
Glucose, fructose and galactose
What bond is formed between 2 monosaccharides?
1,4 glycosidic bond
What is formed when a condensation reaction forms between 2 monosaccharides?
A disaccharide
What is maltose made from?
2 alpha-glucose molecules
What is sucrose made from?
An alpha-glucose molecule and a fructose molecule
What is lactose made from?
An alpha-glucose molecule and a galactose molecule
How are polysaccharides formed?
Joining together of multiple monosaccharides
What is the structure of glycogen?
Branched chain of alpha-glucose molecules, 1,4 and 1,6 glycosidic bonds.
What is the structure of starch?
Made from amylose and amylopectin.
What is the structure of amylose?
Chain of alpha-glucose molecules, 1,4 glycosidic bonds, coiled into spirals
What is the structure of amylopectin?
Branched chains of alpha-glucose molecules, 1,4 and 1,6 glycosidic bonds.
What is the structure of cellulose?
Straight chains of beta-glucose forming strong microfibrils, 1,4 glycosidic bonds
What is the function of starch and glycogen?
Energy stores
What is the function of cellulose?
Structural
How do you conduct the Benedict’s test for reducing sugars?
- Add Benedict’s reagent to a sample.
- Place in water bath to heat.
- If sample forms a green, yellow, orange, brick red precipitate a reducing sugar is present.
- If the sample stays blue a no reducing sugar is present.
How do you conduct the Benedict’s test for non-reducing sugars?
- Add Benedict’s reagent to a sample.
- Place in water bath to heat.
- If stays blue, no reducing sugar present.
- Heat a new sample with dilute HCl.
- Neutralise by adding sodium hydrogencarbonate.
- Heat sample with Benedict’s reagent.
- If sample forms green, yellow, orange, brick-red precipitate non-reducing sugar present.
- If it stays blue, no non-reducing sugar present.
Draw alpha-glucose:
alpha glucose
Draw beta-glucose:
beta glucose
How do you conduct the iodine test for starch?
- Add iodine dissolved in potassium iodide solution to test sample
- If starch is present sample changes from brown to a dark blue-black colour.
