Write the open-chain structure of a four-carbon deoxy sugar.

Deoxy sugars are carbohydrates that have lost one or more hydroxyl (-OH) groups, typically at the 2-position. In the case of a four-carbon deoxy sugar, this means that the sugar will have four carbon atoms and one less oxygen than its corresponding sugar. An example is 2-deoxy-D-ribose, which is a crucial component of RNA.

The open-chain structure of a sugar refers to its linear form, as opposed to its cyclic form. In this structure, the carbon atoms are connected in a straight chain, with functional groups such as aldehydes or ketones at one end. For a four-carbon deoxy sugar, the open-chain structure will consist of four carbon atoms linked by single bonds, with the appropriate hydrogen and oxygen atoms attached.

Structural representation in chemistry involves depicting the arrangement of atoms within a molecule. For sugars, this includes showing the carbon backbone and the positions of functional groups. In drawing the open-chain structure of a four-carbon deoxy sugar, it is essential to accurately represent the carbon atoms, the absence of the hydroxyl group, and the placement of hydrogen atoms to reflect the correct molecular formula.