Placement of the hydroxyl (OH) group in the structural formula for glucose is very important. For example, the structural difference between glucose and galactose are the turning up (or down) of the hydroxyl group for only one of the carbons. The correct structural formula for glucose is shown below as well as the structural formula for galactose to show the very slight difference in organization.
H H
| |
H-C-OH H-C-OH
| |
C -- O C -- O
H /| \ H HO /| \ H
|/ H \| |/ H \|
C C C C
|\ OH H /| |\ OH H /|
HO \| |/ OH H \| |/ OH
C -- C C -- C
| | | |
H OH H OH
Glucose Galactose