DNA Structure Activity

Problem 8: Structure of GC and AT base pairs.


Return to the views labeled "C11-G33 base pair" and "T9-A35 base pair". As first suggested by Watson and Crick, the nitrogen-containing "bases" of DNA interact to form base pairs via hydrogen bond interactions. A pairs with T, and G pairs with C. One technique to visualize H-bonds is to switch between ball-and-stick and space filling mode (using the Toolbar buttons), and note the overlap of the white hydrogen atoms with the nearby electronegative oxygen (red) or nitrogen (blue) atoms. The number of hydrogen bonds between the C11-G33 and T9-A35 base pairs are ______ and _______, respectively.

A. 3, 3
B. 2, 2
C. 3, 2
Within the DNA double helix, A forms 2 hydrogen bonds with T on the opposite strand, and G forms 3 hydorgen bonds with C on the opposite strand.
D. 2, 3

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