Mannose

Here is a 3D model of Mannose. So, 3D Mannose if existed would be the same as real Mannose. So, this is a hexose sugar monomer. In reality, 3D Mannose prototype is present in numerous glycoconjugates including N-linked glycosylation of proteins. C-mannosylation is also abundant and can be found in collage-like regions. As one may see by looking at the 3D model
Mannose molecule structure, it differs a lot from Glucose. So, there is an inversion of the C-2 chiral center that leads to the drastically different chemistry of the two hexoses.