1.1 Carbohydrates Flashcards
What is a monomer?
Subunit that repeats to form a polymer.
What is a polymer?
Complex molecule formed with repeating units called monomers.
Describe a condensation reaction
Condensation is the reaction that forms large, biological molecules.
The reaction releases water and bonds the smaller components together into larger molecules.
Describe a hydrolysis reaction
Hydrolysis is the reaction that breaks down large, biological molecules.
The reaction requires water and splits larger molecules into their smaller components.
Hydrolysis of proteins makes…
Amino acids
Hydrolysis of polysaccharides makes…
Disaccharides and monosaccharides
Hydrolysis of lipids makes…
Fatty acids and glycerol / monoglycerides
Carbohydrates are made from which atoms?
Carbon, oxygen and hydrogen.
What is an isomer?
Same molecular formula but different atom arrangement.
What is the different between the isomers alpha and beta-glucose?
The OH (hydroxyl) groups are in a different orientation around C1.
What is maltose made of?
Glucose + glucose
What is sucrose made of?
Glucose + fructose
What is lactose made of?
Glucose + galactose
What is the bond between two monosaccharides?
Glycosidic bond
How to test for reducing sugars?
- Add Benedict’s reagent
- Heat
- If reducing sugar present, turn from blue to orange/red
How to test for non-reducing sugars?
Step 1: Boil in dilute HCl (to hydrolyse the non-reducing sugar).
Step 2: Neutralise the solution by adding sodium hydrogen carbonate.
Step 3: Add Benedict’s reagent and heat
The result will now be positive if a non-reducing sugar is present. Positive = change from blue to orange/red.
If the solution remains blue, then no sugar is present.
Function of starch
Starch is the main energy storage material in plants. Can be hydrolysed to release glucose.
How is starch structure suited to function?
- Insoluble so doesn’t affect water potential so water not drawn in by osmosis
- Large and insoluble so doesn’t diffuse out of cell
- Compact so a lot can be stored in a small space
- Has a branched form so has many ends that enzymes can simultaneously hydrolyse so quick release of glucose.
How to test for starch?
- Add iodine solution
- If starch is present, colour will change from orange to blue-black.
Function of glycogen
The main energy storage material in animals.
How is the structure of glycogen suited to its function?
- Insoluble so does not affect water potential or draw in water via osmosis.
- Large so doesn’t diffuse out of cells
- Compact so can be stored in a small space
- More highly branched than starch so has ends that can be acted on simultaneously by enzymes to release glucose quickly.
What is the function of cellulose and what is it made of?
Component of the plant cell wall and provides strength and rigidity. It is made of beta-glucose.
What is cellulose structure and how is it suited to its function?
- Made of beta-glucose forming long, straight, unbranched chains.
- Cellulose chains run parallel to each other and are cross linked by hydrogen bonds which provide strength.
- These molecules are grouped to form microfibrils which in turn are grouped to form fibrils which provide strength.
Structure of alpha and beta glucose
