How many different oligosaccharides can be made by linking one glucose and one galactose if the anomeric carbon of glucose is involved in the glycosidic bond? Assume that each sugar is in its pyranose form.
A.
5
B.
4
C.
2
D.
1
E.
3
Would it be 4?
A. 5
Yes, it would be 4.
To understand why, let's break down the process step-by-step:
1. We have one glucose and one galactose.
2. The anomeric carbon of glucose is involved in the glycosidic bond. This means that the glycosidic bond will form between the anomeric carbon of glucose and a hydroxyl group on the galactose.
3. Glucose can exist in two different anomeric forms: alpha and beta. The alpha form has the hydroxyl group on the anomeric carbon pointing below the ring, while the beta form has it pointing above the ring.
4. Galactose can also exist in two different anomeric forms: alpha and beta.
5. Therefore, we have two options for the glucose anomeric form (alpha or beta) and two options for the galactose anomeric form (alpha or beta).
6. The total number of combinations is obtained by multiplying the number of options for each sugar: 2 (glucose) x 2 (galactose) = 4.
Hence, the correct answer is 4.