DNA Structure Activity

Problem 4: The deoxyribose sugar ring


Examine the views labeled "C11-G33 base pair" and "T9-A35 base pair". A, G, C, and T refer to the 4 different nucleotides that are the basic building blocks of DNA. Nucleotides are composed of three components: a phosphate, a sugar, and a nitrogen-containing base. From the "Select Menu" choose "deoxyribose sugar". For a closer look at the sugar, examine the view "sugar (deoxyribose)". Return to the views "C11-G33 base pair" and "T9-A35 base pair", and from the "Select Menu" choose "sugar ring atoms". Notice that each sugar has a ring of atoms with links both to the phosphate group (for review, see Question 1) and the nitrogen-containing base. The sugar ring contains:

A. 5 carbon atoms and no oxygen atoms
B. 5 carbon atoms and 1 oxygen atom
C. 6 carbon atoms
D. 4 carbon atoms and 1 oxygen atom
The deoxyribose sugar ring is formed from carbons atoms 1-4 of the sugar and an hydroxyl oxygen atom, resulting in a five-membered ring. The sugar ring links to the base at the 1'-position, and to two phosphates.

The Biology Project
University of Arizona
Modified: May 27, 1997
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