Resistance to methotrexate, which inhibits the enzyme dihydrofolate reductase (DHFR) is used as a selectable marker. This enzyme is involved in the synthesis of _____ carbon units and is required for _____ biosynthesis.
(a) two, nucleoside
(b) two, nucleotide
(c) one, nucleotide
(d) one, nucleoside
I had been asked this question by my school principal while I was bunking the class.
The query is from Cultured Cells in Mammals and Restricted Areas in Intact Organisms topic in portion Using Other Organisms of Genetic Engineering