Question

Name the parts that make up the backbone of the dna structure.

Answer 1

Sugar+phosphate group ( nucleosides). Because the middle part are the bases

Answer 2

So the backbone of DNA is made up of 6 smaller molecules. Also a 5 carbon sugar called deoxyribose, a phosphate molecule and four different nitrogenous base which are: adenine, thymine, cytosine, and guanine. The rails are made up of alternating sugars and phosphate molecules. 
 
I hoped this helped.! :)