How might you use radioactive isotope

Q1. Sometimes, cDNAs turn out to be “monsters”; that is, fusion of DNA copies of two different mRNAs accidentally inserted adjacent to each other in the same clone. You suspect that a cDNA clone you have isolated from a human heart library is such a monster since the series of the cDNA insert predicts a protein with two structural domains not normally observed in the same protein. How would use the availability of the entire human genome sequence to assess if this cDNA clone is a monster or not?

Q2. Animals obtain energy during a sequence of chemical reaction in which sugar (C6H12O6) and oxygen gas (O2) are reactants. This process produces water (H2O) and carbon dioxide (CO2) as waste products. How might you use radioactive isotope to find out whether the oxygen in CO2 comes from sugar or oxygen gas?