Carbohydrates Flashcards
What are carbohydrates?
Carbohydrates are polymers made from monosaccharides
What are examples of monosaccharides?
Glucose, fructose and galactose
What bond is formed between monosaccharides and disaccharides?
Glycosidic bonds
What are the isomers of glucose and state their structure?
•Alpha and beta glucose
• Alpha has an hydroxyl group facing downwards
• Beta has an hydroxyl group facing upwards
Characteristics of Monosaccharides
Sweet-tasting, Crystal form, white
Structure of glucose and fructose?
Glucose is a hexose while fructose is a pentose
What are the main elements in carbohydrates
Carbon, hydrogen and oxygen
What is the reverse reaction of condensation in the body?
Digestion
What are Disaccharides?
Disaccharides are formed from the condensation of two monosaccharides
List examples of Disaccharides?
Sucrose, maltose and lactose
Which of the disaccharides is a reducing sugar?
Sucrose
List the formulas of disaccharides
Maltose = glucose + glucose
Sucrose = glucose + fructose
Lactose = glucose + galactose
Describe the reducing sugars test
• Add Benedict’s reagent to food sample
• Put in a water bath that has been brought to boil
• Wait for 5 minutes
• Wait till color changes from blue to brick-red
Describe the non-reducing sugars test
• Following the negative reducing sugars test
•Add an acid (HCL) to hydrolysis the bonds
• Add an alkali (NAOH) to neutralize the acid
• Add Benedict’s reagent and heat in a water bath that has been brought to boil
• Wait for 5 minutes
• Reaction is positive if it turns from blue to brick-red
What is the function of a colorimeter
To measure the absorption
How is the colorimeter set to perform its function?
It’s set to different wavelengths due to different size of particles.
Which solution is reduced and which is oxidized
Benedict’s reagent is reduced and sugar solution is oxidized
Define Polysaccharides
They are formed by the condensation of many glucose units
Examples of polysaccharides
Starch, glycogen and cellulose
What is the structure of cellulose
• Made up of many hydrogen bonds
• Forms MICROFIBRILS
•1,4 glycosidic bonds
• amylose
• Long and unbranched
• Made from beta glucose
What is the function of cellulose?
• Provides strength and rigidity
• Structural support
• Found in cell wall
What is the structure of starch
• 1,4 and 1,6 glycosidic bonds
• amylose and amylopectin
• long unbranched and branched
• Made from alpha glucose
What is the function of starch
• Coiled or helical to compact more glucose
• Insoluble so it does not affect water potential
• Found in plants as storage of glucose
What is the structure of glycogen
• 1,4 and 1,6 glycosidic bonds
• long unbranched and highly branched
• Made up of alpha glucose
•Amylose and amylopectin
