STRUCTURE OF MONOSACCHARIDES a deeper dive.pptx

STRUCTURE OF MONOSACCHARIDES a deeper dive.pptx

1. STRUCTURE OF MONOSACCHARIDES

2. The Monosaccharide may be represented by two Structure. They are : Straight chain structure or open chain structure . Cyclic structure or ring structure.

3. Straight chain structure or open chain structure. In the straight-chain structure of glucose, the six carbon atoms are arranged in a continuous linear sequence, with each carbon atom bonded to adjacent atoms through covalent bonds. This configuration allows the glucose molecule to exist in an extended form. Known as an open-chain structure, this form of glucose differs from its cyclic counterpart, as the molecule's two terminal ends, the aldehyde group at one end and the hydroxyl group at the other, remain unlinked. These unconnected ends allow the molecule to participate in various chemical reactions, such as oxidation, which are essential for metabolic processes like glycolysis. This open-chain form is less stable compared to the ring structure and exists in equilibrium with the cyclic form in aqueous solutions.

4. Fischer proposed another type of straight-chain structure for glucose, known as the Fischer projection formula. In this model, Fischer placed the aldehyde group (–CHO) at one end of the molecule, while the remaining carbon atoms are arranged vertically, one behind the other. At the opposite end, the last carbon atom is bonded to two hydrogen atoms and one hydroxyl group (–OH). For the intermediate carbon atoms, each is attached to a hydrogen atom on one side and a hydroxyl group on the other. This arrangement provides a simplified, two-dimensional representation of glucose, making it easier to visualize the molecule’s stereochemistry and the orientation of its functional groups. Fischer projections are widely used to depict the three-dimensional structure of sugars and other organic molecules.

5. Cyclic structure or Ring structure In the cyclic structure of sugars, the atoms are arranged in a ring-like formation. In 1929, English chemist Norman Haworth developed the representation of this ring structure, which became known as Haworth’s projection formula. This method of depiction is commonly used to show the cyclic forms of sugar molecules. Sugars can exist in two types of ring structures: the furanose ring , which is a five-membered ring, and the pyranose ring , which is a six-membered ring. The formation of these rings results from the interaction between the carbonyl group and a hydroxyl group within the sugar molecule, leading to a more stable cyclic form compared to the open-chain structure.

6. Furanose Ring Furanose is a five-membered ring with a pentagonal shape. It resembles the structure of a compound called furan, which is why it is named the furanose ring. The ring consists of four carbon atoms and one oxygen atom, forming a stable, cyclic structure. This configuration is commonly found in certain sugars, such as fructose, where the furanose form represents the five-membered cyclic arrangement of atoms.