Ring Structures Flashcards
What are the two structures in which monosaccharides exist?
Straight-chain structures and ring structures
Represented by Fischer projections and ring forms
What is the equilibrium mixture of D-glucose in solution composed of?
Straight-chain form and ring form
The precise ratio depends on each molecule’s physical properties
What are five-atom carbohydrate ring structures called?
Furanose rings
Composed of four carbons and one oxygen
What are six-atom carbohydrate ring structures called?
Pyranose rings
Composed of six atoms, including five carbons and one oxygen
What is the source of the oxygen in carbohydrate rings?
An alcohol group in the molecule
Reacts with another carbon to form a ring
What type of bond is formed when the –OH group on carbon-5 reacts with carbon-1 in glucose?
Hemiacetal bond
Involves rearrangement of functional groups
What is the anomeric carbon?
The reacted carbon in the ring structure
It is where the hemiacetal group is formed
What distinguishes the alpha form from the beta form of glucose?
The orientation of the –OH group at carbon-1
Alpha has –OH down, beta has –OH up
How are anomers interconverted?
Through the open-chain molecule
This process is called mutarotation
What is mutarotation?
The interconversion of anomers
Involves conversion between alpha and beta forms
In a polysaccharide, what form of monosaccharides is found?
Ring form only
Due to bonding at the anomeric carbon
What type of bonding occurs between monosaccharides?
Covalent bonding
Covered in the next section
Fill in the blank: The conversion of a Fischer projection into a cyclic _______ projection for glucose is a common representation.
Haworth
True or False: The carbon numbering in the Haworth projection differs from that in the Fischer projection.
False
The carbon numbering remains consistent
What is the general relationship between the stability of different ring forms of carbohydrates?
One form is more stable than the other
Most compounds can interconvert freely
