Carbohydrates-polysaccharides Flashcards
What are the three main polysaccharides mentioned?
Cellulose, starch, glycogen
These are polymers of glucose formed through condensation reactions.
What type of glucose forms glycogen and starch?
a-glucose
Glycogen and starch are formed by the condensation of a-glucose.
What type of glucose forms cellulose?
B-glucose
Cellulose is formed by the condensation of B-glucose.
List the properties of polysaccharides.
- Do not taste sweet
- Relatively insoluble in water
- Non-reducing
- Function as storage or structural molecules
Examples include starch and glycogen for storage, cellulose for structure.
What is the primary function of starch in plants?
Storage carbohydrate
Starch consists of long, branched chains of a-glucose molecules.
Describe the structure of starch.
- Long, branched chains of a-glucose
- Linked by glycosidic bonds
- Forms a helical shape
This structure allows for compact storage.
Why is starch ideally suited for storage?
- Large size prevents crossing cell membrane
- Insoluble and osmotically inactive
- Helical shape forms a compact store
- Branched structure allows easy glucose release
These features prevent cell damage and facilitate respiration.
How can starch be detected in a sample?
Iodine test
Adding 2-3 drops of iodine/potassium iodide solution produces a blue/black color if starch is present.
What color indicates the presence of starch in the iodine test?
Blue/black
If no starch is present, the iodine solution remains orange/yellow.
True or False: Polysaccharides taste sweet.
False
Polysaccharides do not taste sweet.
Fill in the blank: Polysaccharides are formed by the joining of glucose molecules during _______.
condensation reactions
This process leads to the formation of polymers.
What is the storage carbohydrate found in the cytoplasm of animal cells?
Glycogen
Glycogen is formed by the condensation of a-glucose.
In which tissues is glycogen stored in mammals?
Liver and muscles
Glycogen is stored in large amounts in these tissues.
Why is glycogen ideally suited to its function as a storage compound?
It is insoluble and has a branched structure
This prevents water influx by osmosis and allows rapid hydrolysis for glucose release.
What type of glucose molecule is glycogen formed from?
a-glucose
Glycogen is synthesized through the condensation of a-glucose.
What is cellulose and where is it found?
Cellulose is found in the cell wall of plants
It provides rigidity and shape to the cell.
What prevents plant cells from bursting due to osmosis?
Cellulose
It maintains the integrity of the plant cell wall.
What type of glucose molecules make up cellulose?
B-glucose
Cellulose is a polymer of B-glucose molecules.
How are B-glucose molecules in cellulose joined together?
By glycosidic bonds
These bonds are formed in condensation reactions.
What structural feature distinguishes cellulose from starch?
Every other B-glucose monomer is inverted
This inversion affects the structure and properties of cellulose.
What is formed when hydroxyl groups project from either side of the B-glucose chain in cellulose?
Hydrogen bonds
These bonds form between adjacent cellulose chains, contributing to the strength of the microfibril.
What is the three-dimensional structure produced by hydrogen bonding in cellulose?
Microfibril
This structure provides strength to plant cell walls.
