Practice Questions for BIOCH 200 Nucleic Acids
1. ATP and other nucleoside triphosphates are described as a “high energy” molecules.
The term is used because the phosphoanhydride bonds in the triphosphate portion of
the molecules are “easily” broken and the energy they contain is therefore readily
available. Why are these bonds “easily” broken?
The Pi makes a great leaving group; the bond is “easily” broken, because:
a) The Pi has more resonance stabilization structures alone than it does in a
b) when Pi groups are joined via phosphoanhydride bonds, there is significant
electrostatic repulsion between the negatively charged oxygen atoms.
2. Look carefully at the chemical structures shown on the following page. By assigning
the correct letters, match each statement with ALL of the structures to which it
i. Either is or contains a purine base. _____________A, B, C, D, F___________
ii. Contains deoxyribose. _________E______________________________
iii. Is or contains a nucleotide but not a deoxynucleotide. ______B, C, F_____
iv. Contains a phosphodiester bond. _____________E____________________
v. Is or contains any one of the bases C, U, or T. _____E________________
vi. Is a nucleoside diphosphate. _______B__________________________
vii. Is a dinucleotide. _________________C,E __________________________
Choice “E” may continue from the 5’ phosphate, so may be longer than a dinucleot