Carbohydrates Flashcards
What are carbohydrates made of ?
Carbon , Hydrogen and Oxygen
What is the main purpose of carbohydrates in plants and animals ?
Store energy
What are monosaccharides ?
Simple sugars that cannot be broken down into other sugars.
A single sugar unti
Sweet and soluble
Give examples of monosaccharides
Glucose
Fructose
Galactose
What are disaccharides?
Two monosaccharides bonded together.
Give examples of disaccharides and what 2 monosaccharides they are made up of.
Maltose ( 2x glucose)
Sucrose ( Fructose and glucose)
Lactose ( Glucose and Galatose)
What are polysaccharides?
Chain of many monosaccharides bonded together.
Give examples of polysaccharides
Cellulose , starch and glycogen
What is the general formula of monosaccharides?
(CH2O)n
How many carbons does glucose have and therefore what type of sugar is it ?
6 therefore is is a Hexose.
How many carbons does Ribose have and therefore what type of sugar is it ?
5 - Pentose
Write down what type of sugar a molecule is depending on it quantity of carbons.
Mono -1 Di -2 Tri -3 Tetra -4 Pent-5 Hex-6 Poly- Many
Which way are the carbons numbered ?
Clockwise
What’s an isomer ?
The hydroxyl group is below the carbon 1 in alpha glucose and above carbon 1 in beta glucose.
Deadcjbe how maltose ( a disaccharide) can be formed ?
Two alpha glucose molecules (C1 and C4) meet.
Oh hydroxyl group from 1 glucose and H from the other glucose react.
Water is expelled as this is a condensation reaction.
It is called a a-1,4 glycosidic bond
What is the final bond in maltose called ?
a-1,4 glycosidic bond
How can a disaccharide become a monosaccharide again ?
Reversed bonding by hydrolysis
What is Benedictus test and describe how this was done.
The test for a reducing sugar.
2cmcubed of a food sample into a test tube and grind if not in liquid form.
Add equal volume of Benedictus solution and place in boiling water bath for 5 minutes.
An orange or brown colour indicates a presence of reducing sugar.
What happens if the colour does not change after Benedictus test and how is this tested ?
If the solution remains blue then sugar is not present.
Add another 2cm cubes of a food sample and hydrochloride acid into a test tube and place in boiling water bath for 5 minutes. The acid will hydrolyse any disaccharide present into monosaccharides.
Retest the solution using the Benedictus method.
If non- reducing sugar was present in the original sample you will not see an orange or brown colour. This is because reducing sugars were produced from the hydrolysis of the non-reducing sugar.
Which monomers make up starch ?
Alpha-glucose
Which monomers make up cellulose ?
Beta- glucose
Why is sucrose classifies as a carbohydrate ?
Carbon and hydrogen are in a 2:1 ration which is the same as water.
Explain why sucrose will prodcuee a positive result with Benedictus test only after it has been boiled with dilute acid.
Once the glycosidic bond has been hydrolysed, reducing sugars in the form of glucose and fructose monosaccharides will be formed.
Explain how proteins are suited to their roles as receptor molecules. Thanks
Many different types of proteins have different primary structures due to their different sequence of amino acids. This gives a tertiary structure and allows the formation of a receptor binding site in which the substrate can fit.
Explain why glucose and maltose both taste sweet but starch does not.
Glucose and maltose are soluble but starch is insoluble.
Describe a chemical test to identify starch.
Add iodine solution.
If it turns black or deep blue, starch is present.