Test to distinguish between starch and cellulose
Answers
Answer:
Starch vs. Cellulose: Structure
The structure formed when the molecules share oxygen is determined by which form of glucose is linked together. Starch contains alpha glucose, while cellulose is made of beta glucose. This difference may seem minor, but it plays a big role in the 3-D shape of the molecule. Think of a pile of wood that can be put together in different ways. If you put the wood together in one way, it makes a doghouse; put together another way, it becomes a bookcase. In the same way, starch and cellulose have different 3-D structures.
It takes anywhere from 250 to over 1,000 glucose molecules to make a single starch molecule. In alpha glucose, the OH on carbon 1 and 4 are facing the same way. This means it can link in a straight chain or branch off, like people standing next to each other all facing the same way. Because starch can be straight and faces the same way, it can roll itself up in a helical structure, kind of like rolling up a piece of paper so it takes less space. If the alpha glucose of a starch branches off, the structure is more like paper that's folded up to make origami.
Cellulose, on the other hand, is composed of about 500 glucose molecules in the beta form. Because the OH of carbon 1 and carbon 4 are in a different place, the molecules are flip-flopped when connected, like people standing next to each other with one facing forward while the other faces the opposite direction. This pattern allows for hydrogen bonding between two molecules of cellulose.