Structure And Properties Of Starch Flashcards
Where is glucose produced?
In plant cells.
How is glucose produced?
Using light energy.
When is glucose produced?
During photosynthesis.
What is glucose?
A store of chemical energy which can be released during respiration.
Why is glucose extremely hydrophilic and soluble in water?
It contains a large number of hydroxyl groups.
Why are hydroxyl groups polar?
Due to the negative charge on the oxygen atom and positive charge on the hydrogen atom.
What can hydroxyl groups form?
Hydrogen bonds with water molecules.
What is a problem with glucose’s solubility?
If a cell contains a large amount of dissolved glucose then it can cause water to move into the cell by osmosis.
How do plants solve glucose’s solubility problem?
They store glucose as starch.
Where do we find starch?
In starch grains.
What two molecules does starch consist of?
Amylose and amylopectin.
What are amylose molecules?
Polymers of alpha glucose molecules.
What do amylose molecules/chains form?
A compact helix.
What forms between the molecules/chains of glucose in amylose?
Hydrogen bonds.
What happens when the cell needs glucose?
Water is used to break the glycosidic bonds in starch (starch is hydrolysed).
What does the helical shape in amylose help with?
To make starch a compact molecule.
What are amylopectin molecules?
Chains of alpha glucose molecules with a branch of another alpha glucose chain every 25-30 glucoses.
What is the difference between the polysaccharide amylose and amylopectin?
Amylose is unbranched whereas amylopectin is heavily branched.
Why does starch have to be insoluble?
So it doesn’t cause water to enter the cell by osmosis.
Why can’t amylose and amylopectin diffuse out of starch?
They are very large polymers.
What are used to hydrolyse starch and break the glycosidic bonds?
Enzymes.
Why can enzymes break down starch easily?
Since enzymes act at the ends of molecules and amylopectin in starch has a lot of branches and ends.
