Q5 **Question:**If the following monosaccharide underwent cyclization to form a furanose, which of the following is one of the possible structures that would be seen?**Image Description:**Above the options is a linear monosaccharide structure:1. **Linear Structure:** - Vertical structure with five carbon atoms. - Contains hydroxyl (OH) groups attached to the second, third, and fourth carbon, a hydrogen atom attached to the first and fifth carbon, and a carbonyl group (C=O) attached to the first carbon. - A CH₂OH group is attached at both ends, to the first and the fifth carbon.Below this structure are four cyclized structures labeled A, B, C, and D.2. **Cyclized Structures:** - **Option A:** - Five-membered ring (furanose) with an oxygen atom in the ring. - Hydroxyl groups are attached to the second, third, fourth, and fifth carbon. - CH₂OH group is above the ring on the fifth carbon. - **Option B:** - Five-membered ring (furanose) with an oxygen in the ring. - Hydroxyl groups are attached to the first, second, and third carbon. - CH₂OH group is above the ring on the first carbon. - **Option C:** - Six-membered ring with an oxygen atom in the ring. - Hydroxyl groups are attached to the second, third, fourth, and fifth carbon. - CH₂OH group is above the ring on the fifth carbon. - **Option D:** - Six-membered ring with an oxygen atom in the ring. - Hydroxyl groups are attached to the first, second, third, and fourth carbon. - CH₂OH group is above the ring on the first carbon.**Options:**- A- B- C- D

Carbohydrates are polyhydroxy aldehydes or ketones. They can be classified as monosaccharides, oligosaccharides or polysaccharides. Monosaccharides contain a single polyhydroxy aldehyde or ketone unit. In monosaccharides, if the carbonyl group is at the end of the chain, they are called aldose. If the carbonyl group is at any other position, they are called ketose. Monosaccharides with 3, 4, 5, 6 and 7 carbons in their carbon skeleton are called trioses, tetroses, pentoses, hexoses and heptose respectively. If a monosaccharide has a carbonyl group at one end and six carbons in its skeleton, it would be called an aldohexose If a monosaccharide has a carbonyl group at any other position and six carbons in its skeleton, it would be called a ketohexose.Ring structures for monosaccharides are drawn in Haworth projections Haworth Projections Two-dimensional representations of the cyclic structure of monosaccharides are called Haworth projections. In Haworth projection, the ring's plane is perpendicular to the paper. Groups pointing up are above the plane and groups pointing down are below the plane of the ring. When the anomeric hydroxyl group is on the same side as carbon 6 of a hexose in Haworth projection of the hexose, the structure is called β structure; if they are on the opposite side then the structure is called α form. Open chain structures for monosaccharides are drawn in Fischer projections. Fischer Projections It is the three-dimensional representation of chiral centres on paper. Horizontal lines represent groups projecting towards the reader while vertical lines represent groups projecting away from the reader. The guidelines for converting Fischer projections to Haworth projections are as follows: If the hydroxyl on C5 is on the right in the Fischer then it is on the top in Haworth. If the hydroxyl on C5 is on the left in the Fischer then it is at the bottom in Haworth. For C2, C3 and C4, hydroxyl on left in Fischer mean top in Haworth and hydroxyl on right in Fischer means bottom in Haworth. Following these guidelines, we draw the structure of the given ketohexose and compare it with the available option to find the best match. We can eliminate options C and D since they represent pyranose structure. Out of options A and B, which represent furanose structure, Option B matches the second structure of in the image. The correct choice is option B