G Deoxyribonucleotides, which are DNA precursors, are derived from ribonucleotides. Ribonucleotide reductase catalyzes the conversion. Answer the five questions about ribonucleotide reductase. Which of these are substrates of the ribonucleotide reductase reaction? dGDP CDP GDP dCTP Which of these are products of the ribonucleotide reductase reaction? dGDP dCTP GDP CDP What is the best description for the reaction? isomerization phosphorylation oxidation–reduction hydrolysis group transfer What is the ultimate electron donor? NADH NADPH FADH2 FAD NAD+ Which of these can directly donate an electron to ribonucleotide reductase? NADH thioredoxin reductase NADPH thioredoxin