In the following model, the carbon atoms are dark gray, hydrogen is cyan and oxygen is red. There are three chiral centers (numbered). The molecule is not shown in a conformation that reflects the Fischer projection formula, because such a structure is unstable due to crowding. The zig-zag conformation shown has staggered C-C bonds which are preferred by linear molecules of this kind. The configuration at the center farthest from the carbonyl group (C-4) determines the D or L classification. This carbon may be identified by clicking the first button below (it will be colored magenta).
In the following model, the carbon atoms are dark gray, hydrogen is cyan and oxygen is red. There are four chiral centers (numbered). The anomeric carbon atom will be colored green when the first button is clicked.