Amylose – The Straight (and helical) One Flashcards
(14 cards)
What is amylose?
A linear (and helical) chain of glucose units that makes up 18-33% of starch by weight
Amylose is predominantly located in the interior of starch granules.
What type of bond links glucose residues in amylose?
α-(1,4) glycosidic bonds
Each bond results in the loss of a water molecule.
What is the molecular weight range of amylose?
26-31x10^4
This range reflects the size of amylose molecules.
How many glucose residues are in each turn of the amylose helix?
Six glucose residues
This contributes to the helical structure of amylose.
What are glucose molecules referred to as when they are part of a polymer?
Residues
They are no longer complete molecules once bound.
What happens when a glycosidic bond is formed?
A molecule of water is lost
This is why glycosidic bonds are considered condensation reactions.
What distinguishes an α-(1,4) glycosidic bond from a β-(1,4) glycosidic bond?
The position of the hydroxyl group on carbon number 1
α-glucose has the hydroxyl group below the plane, while β-glucose has it above.
What is the significance of the helical structure of amylose?
It contributes to its insolubility in cold water and higher density compared to amylopectin
This structure also makes amylose a resistant starch.
True or False: β-glycosidic bonds are found in starch.
False
β-glycosidic bonds are found in cellulose and β-glucans, not starch.
What type of reaction occurs when forming a glycosidic bond?
Condensation reaction
This is due to the loss of water during bond formation.
Fill in the blank: Amylose is more resistant to digestion in human digestive systems than _______.
amylopectin
This resistance is due to its tight helical structure.
What is the general structural feature of amylose?
An unbranched helical chain
This feature differentiates it from amylopectin.
What is the role of carbon atom numbering in glucose?
It helps identify the specific carbons involved in glycosidic bond formation
Numbering starts after the aldehyde (CHO) end.
What is a glycosidic bond?
A covalent bond joining sugar molecules, also called glycosides
This bond is crucial for forming polysaccharides.
