Question

DNA synthesis can be specifically measured by estimating the incorporation of radio labelled

• A. thymidine
• B. deoxyribose sugar
• C. uracil
• D. adenine.

Answer 1

Answer: (A)

Autoradiography is the study of labelled precursors like ${}^{3}H$ by knowing the movement of radioactivity with the help of photographic films and emulsions at short intervals. Study of DNA requires radioactive material tritiated thymidine which is formed by replacing normal hydrogen of thymidine with ${}^{3}H$ (heavy isotope of hydrogen). Thymidine only is used for this purpose because RNA will not be labelled by this.