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Describe the chemical differences between a ribonucleoside triphosphate and a deoxyribonucleoside monophosphate.

Using Fig. 3-3a as a guide, draw the complete structure of a nucleoside triphosphate before and after it becomes incorporated into a polynucleotide chain. Draw the structure that would result if the newly formed phosphodiester bond were hydrolyzed.

Kinases are enzymes that transfer a phosphoryl group from a nucleoside triphosphate. Which of the following are valid kinase-catalyzed reactions?

(a)$\mathbf{ATP}\mathbf{+}\mathbf{GDP}\mathbf{→}\mathbf{ADP}\mathbf{+}\mathbf{GTP}$

(b)$\mathbf{ATP}\mathbf{+}\mathbf{GMP}\mathbf{→}\mathbf{AMP}\mathbf{+}\mathbf{GTP}$

Explain the structural basis for Chargaff’s rules.

Using a three-dimensional computer model of the DNA molecule (such as shown in Interactive Exercise 1), identify each of the following structural features: the 3′ and 5′ end of each strand, the atoms that make up the sugar-phosphate backbone, the major and minor grooves, the bases in several base pairs, and the atoms that participate in hydrogen bonding in A =T and G=C base pairs.

Question: Kinases are enzymes that transfer a phosphoryl group from a nucleoside triphosphate. Which of the following are valid kinase-catalyzedreactions?
(a)
(b)

A diploid organism with a 45,000-kb haploid genome contains 21% G residues. Calculate the number of A, C, G, and T residues in the DNA of each cell in this organism.

List the structural differences between DNA and RNA.

Explain why the double-stranded nature of DNA is relevant for copying and transmitting genetic information when a cell divides.

A segment of DNA containing 20 base pairs includes 7 guanine residues. How many adenine residues are in the segment? How many uracil residues are in the segment?